Surgery_Schwartz

Surgery_Schwartz. main histologic growth patterns are spindle cell, squamoid, and pleomorphic giant cell. Tumors may show a predominance of one pattern or a mixture of various patterns. Foci of more differentiated thy-roid tumors, either follicular or papillary, may be seen, suggest-ing that anaplastic tumors arise from more well-differentiated tumors.Treatment and Prognosis. This tumor is one of the most aggressive thyroid malignancies, with few patients surviving 6 months beyond diagnosis. All forms of treatment have been disappointing. The ATA has published guidelines for the man-agement of patients with anaplastic cancer.62 Imaging (ultra-sound, CT, MRI, or PET-CT) should be obtained to assess resectability. All patients should have preoperative laryngos-copy to assess the status of the vocal cords. A total or near-total thyroidectomy with therapeutic lymph node dissection is rec-ommended for patients with an intrathyroidal mass (although lobectomy may also be appropriate, particularly if there is


Surgery_Schwartz

Surgery_Schwartz. total or near-total thyroidectomy with therapeutic lymph node dissection is rec-ommended for patients with an intrathyroidal mass (although lobectomy may also be appropriate, particularly if there is concern for vocal cord paralysis). If extrathyroidal extension is present, an en bloc resection should be considered if all gross disease can be removed (R1). Tracheostomy should be avoided as long as possible unless there is impending airway loss. Adjuvant radiation which should be offered to patients with a good performance status and no metastatic disease who desire aggressive management. Cytotoxic chemotherapy (with some combination of a taxane, anthracycline, and platinum) is typi-cally given concurrently and has been associated with prolonged survival, although these agents are also being used in a neoadju-vant fashion, particularly in patients with unresectable disease.Lymphoma Lymphomas account for <1% of thyroid malignan-cies, and most are of the non-Hodgkin’s B-cell type.


Surgery_Schwartz

Surgery_Schwartz. being used in a neoadju-vant fashion, particularly in patients with unresectable disease.Lymphoma Lymphomas account for <1% of thyroid malignan-cies, and most are of the non-Hodgkin’s B-cell type. Although the disease can arise as part of a generalized lymphomatous con-dition, most thyroid lymphomas develop in patients with chronic lymphocytic thyroiditis. Chronic antigenic lymphocyte stimu-lation has been suggested to result in lymphocyte transforma-tion. Patients usually present with symptoms similar to those of patients with anaplastic carcinoma, although the rapidly enlarg-ing neck mass often is painless. Patients may present with acute respiratory distress. Ultrasound can be useful for early diagno-sis, and lymphoma appears as a well-defined hypoechoic mass. The diagnosis usually is suggested by FNAB, but FNAB can be nondiagnostic, particularly in the setting of low-grade lym-phomas. Therefore, needle core or open biopsy may be neces-sary for definitive diagnosis. Staging studies


Surgery_Schwartz

Surgery_Schwartz. by FNAB, but FNAB can be nondiagnostic, particularly in the setting of low-grade lym-phomas. Therefore, needle core or open biopsy may be neces-sary for definitive diagnosis. Staging studies should be obtained expeditiously to assess the extent of extrathyroidal spread.Brunicardi_Ch38_p1625-p1704.indd 165701/03/19 11:21 AM 1658SPECIFIC CONSIDERATIONSPART IITreatment and Prognosis. Patients with thyroid lymphoma respond rapidly to chemotherapy (CHOP—cyclophosphamide, doxorubicin, vincristine, and prednisone), which also has been associated with improved survival. Combined treatment with radiotherapy and chemotherapy often is recommended. Thy-roidectomy and nodal resection are used to alleviate symptoms of airway obstruction in patients who do not respond quickly to the above regimens or who have completed the regimen before diagnosis. Prognosis depends on the histologic grade of the tumor and whether the lymphoma is confined to the thy-roid gland or is disseminated. The overall


Surgery_Schwartz

Surgery_Schwartz. or who have completed the regimen before diagnosis. Prognosis depends on the histologic grade of the tumor and whether the lymphoma is confined to the thy-roid gland or is disseminated. The overall 5-year survival rate is about 50%; patients with extrathyroidal disease have markedly lower survival rates.Metastatic Carcinoma The thyroid gland is a rare site of metastases from other cancers, including kidney, breast, lung, and melanoma. Clinical examination and a review of the patient’s history often suggest the source of the metastatic dis-ease, and FNAB usually provides definitive diagnosis. Resec-tion of the thyroid, usually lobectomy, may be helpful in many patients, depending on the status of their primary tumor.Thyroid Surgery Conduct of Thyroidectomy Patients with any recent or remote history of altered phonation or prior neck or upper chest surgery that places the recurrent laryngeal or vagus nerves at risk should undergo vocal cord assessment by direct or indirect laryngos-copy


Surgery_Schwartz

Surgery_Schwartz. history of altered phonation or prior neck or upper chest surgery that places the recurrent laryngeal or vagus nerves at risk should undergo vocal cord assessment by direct or indirect laryngos-copy before thyroidectomy. Laryngeal examination is also advised in patients with known posterior extension of thyroid cancer and extensive central nodal metastases.40 The patient is positioned supine, with a sandbag between the scapulae. The head is placed on a donut cushion, and the neck is extended to provide maximal exposure. A Kocher transverse collar incision, typically 3 to 5 cm in length, is placed in or parallel to a natu-ral skin crease 1 cm below the cricoid cartilage (Fig. 38-22A), although longer incisions may be needed. The subcutaneous tis-sues and platysma are incised sharply, and subplatysmal flaps are raised superiorly to the level of the thyroid cartilage and inferiorly to the suprasternal notch (Fig. 38-22B). The strap muscles are divided in the midline along the entire


Surgery_Schwartz

Surgery_Schwartz. subplatysmal flaps are raised superiorly to the level of the thyroid cartilage and inferiorly to the suprasternal notch (Fig. 38-22B). The strap muscles are divided in the midline along the entire length of the mobilized flaps, and the thyroid gland is exposed. On the side to be approached first, the sternohyoid muscles are sepa-rated from the underlying sternothyroid muscle by blunt dissec-tion until the internal jugular vein and ansa cervicalis nerve are identified. The strap muscles rarely need to be divided to gain exposure to the thyroid gland. If this maneuver is necessary, the muscles should be divided high to preserve their innervation by branches of the ansa cervicalis. If there is evidence of direct tumor invasion into the strap muscles, the portion of involved muscle should be resected en bloc with the thyroid gland. The sternothyroid muscle is then dissected off the underlying thyroid by a combination of sharp and blunt dissection, thus exposing the middle thyroid veins.


Surgery_Schwartz

Surgery_Schwartz. resected en bloc with the thyroid gland. The sternothyroid muscle is then dissected off the underlying thyroid by a combination of sharp and blunt dissection, thus exposing the middle thyroid veins. The thyroid lobe is retracted medially and anteriorly, and the lateral tissues are swept posterolaterally using a peanut sponge. The middle thyroid veins are ligated and divided (Fig. 38-22C). Attention is then turned to the midline where Delphian nodes and the pyramidal lobe are identified. The fascia just cephalad and caudad to the isthmus is divided. The superior thyroid pole is identified by retracting the thyroid first inferiorly and medially, and then the upper pole of the thy-roid is mobilized caudally and laterally. The dissection plane is kept as close to the thyroid as possible, and the superior pole vessels are individually identified, skeletonized, ligated, and divided low on the thyroid gland to avoid injury to the exter-nal branch of the superior laryngeal nerve (Fig.


Surgery_Schwartz

Surgery_Schwartz. and the superior pole vessels are individually identified, skeletonized, ligated, and divided low on the thyroid gland to avoid injury to the exter-nal branch of the superior laryngeal nerve (Fig. 38-22D). Once these vessels are divided, the tissues posterior and lateral to the superior pole can be swept from the gland in a posteromedial direction, to reduce the risk of damaging vessels supplying the upper parathyroid.The RLNs should then be identified, and the ATA 2015 guidelines strongly recommend visual identification in all cases.40 The course of the right RLN is more oblique than the left RLN. The nerves can be most consistently identified at the level of the cricoid cartilage. The parathyroids usually can be identified within 1 cm of the crossing of the inferior thyroid artery and the RLN, although they also may be ectopic in loca-tion. The lower pole of the thyroid gland should be mobilized by gently sweeping all tissues dorsally. The inferior thyroid vessels are dissected,


Surgery_Schwartz

Surgery_Schwartz. the RLN, although they also may be ectopic in loca-tion. The lower pole of the thyroid gland should be mobilized by gently sweeping all tissues dorsally. The inferior thyroid vessels are dissected, skeletonized, ligated, and divided as close to the surface of the thyroid gland as possible to minimize devascular-ization of the parathyroids (extracapsular dissection) or injury to the RLN. The RLN is most vulnerable to injury in the vicinity of the ligament of Berry. The nerve often passes through this structure along with small crossing arterial and venous branches (Fig. 38-22E). Any bleeding in this area should be controlled with gentle pressure before carefully identifying the vessel and ligating it. Use of the electrocautery should be avoided in prox-imity to the RLN. Once the ligament is divided, the thyroid can be separated from the underlying trachea by sharp dissection. The pyramidal lobe, if present, must be dissected in a cephalad direction to above the level of the notch in


Surgery_Schwartz

Surgery_Schwartz. is divided, the thyroid can be separated from the underlying trachea by sharp dissection. The pyramidal lobe, if present, must be dissected in a cephalad direction to above the level of the notch in the thyroid cartilage or higher in continuity with the thyroid gland. If a lobectomy is to be performed, the isthmus is divided flush with the trachea on the contralateral side and suture ligated. The procedure is repeated on the opposite side for a total thyroidectomy.Parathyroid glands located anteriorly on the surface of the thyroid that cannot be dissected from the thyroid with a good blood supply or that have been inadvertently removed during the thyroidectomy should be resected, confirmed as parathy-roid tissue by frozen section, divided into 1-mm fragments, and reimplanted into individual pockets in the sternocleido-mastoid muscle. The sites should be marked with silk sutures and a clip. Various novel techniques using indocyanine fluo-rescence angiography and near-infrared


Surgery_Schwartz

Surgery_Schwartz. individual pockets in the sternocleido-mastoid muscle. The sites should be marked with silk sutures and a clip. Various novel techniques using indocyanine fluo-rescence angiography and near-infrared autofluorescence have shown utility in the identification and viability assessment of parathyroid glands; however, they are not routinely used at the present time.63,64 If a subtotal thyroidectomy is to be performed, once the superior pole vessels are divided and the thyroid lobe mobilized anteriorly, the thyroid lobe is cross-clamped with a Mayo clamp, leaving approximately 4 g of the posterior por-tion of the thyroid. The thyroid remnant is suture ligated, taking care to avoid injury to the RLN. Routine drain placement rarely is necessary. After adequate hemostasis is obtained, the strap muscles are reapproximated in the midline. The platysma is approximated in a similar fashion. The skin can be closed with subcuticular sutures or clips.Nerve Monitoring Intraoperative RLN and external


Surgery_Schwartz

Surgery_Schwartz. are reapproximated in the midline. The platysma is approximated in a similar fashion. The skin can be closed with subcuticular sutures or clips.Nerve Monitoring Intraoperative RLN and external laryngeal nerve monitoring techniques are being increasingly used during thyroid and parathyroid surgery. Both continuous monitoring using endotracheal tube electrodes and intermittent monitor-ing by periodic stimulation and laryngeal palpation are used. Many published studies have established the feasibility of nerve monitoring; however, none were able to show that the technique equivocally reduces nerve injury (particularly by experienced Brunicardi_Ch38_p1625-p1704.indd 165801/03/19 11:21 AM 1659THYROID, PARATHYROID, AND ADRENALCHAPTER 38Figure 38-22. Conduct of thyroidectomy. A. Correct placement of thyroidectomy incision. B. Raising subplatysmal flaps. C. Dissection of middle thyroid vein. D. Dissection of the superior pole vessels, which should be individually ligated. E. Dissection at


Surgery_Schwartz

Surgery_Schwartz. of thyroidectomy incision. B. Raising subplatysmal flaps. C. Dissection of middle thyroid vein. D. Dissection of the superior pole vessels, which should be individually ligated. E. Dissection at the ligament of Berry. Note small artery and vein within the ligament and the recurrent laryngeal nerve coursing laterally. F. Endoscopic thyroidectomy via axillary incisions. m. = muscle; n. = nerve; v. = vein.IncorrectCricoid cartilageCorrectAPlatysmaCauteryFive straight clamps on dermisBMiddle thyroid v.CCricothyroid m.External branch ofsuperior laryngeal n.Superior thyroid vesselsDBrunicardi_Ch38_p1625-p1704.indd 165901/03/19 11:21 AM 1660SPECIFIC CONSIDERATIONSPART IISmall artery & veinin ligament of BerryRecurrent laryngeal n.ThyroidEFFigure 38-22. (Continued)surgeons and especially when the RLN is routinely visually identified) until recently. In 2009, Barczynski and colleagues65 were the first to demonstrate in their prospective randomized trial with 2000 nerves at risk that


Surgery_Schwartz

Surgery_Schwartz. when the RLN is routinely visually identified) until recently. In 2009, Barczynski and colleagues65 were the first to demonstrate in their prospective randomized trial with 2000 nerves at risk that neuromonitoring was asso-ciated with a statistically significant improvement in transient RLN injury rates when compared to the practice of visualiza-tion of the nerve alone and particularly in patients at higher risk of nerve injury. Of note, there was no difference in permanent RLN injury rates, and a later meta-analysis of all the published studies also failed to show a protective effect of neuromonitor-ing. Despite conflicting data, the technology has become widely adopted. The current ATA guidelines recommend that intraop-erative neural stimulation may be used to facilitate nerve iden-tification of the RLN and confirm its function, especially prior to proceeding with contralateral thyroidectomy.Minimally Invasive Approaches Several approaches to minimally invasive thyroidectomy have


Surgery_Schwartz

Surgery_Schwartz. of the RLN and confirm its function, especially prior to proceeding with contralateral thyroidectomy.Minimally Invasive Approaches Several approaches to minimally invasive thyroidectomy have been described. Miniincision procedures use a small, 3-cm incision with no flap creation and minimal dissection to deliver the thyroid into the wound and then perform the pretracheal and paratracheal dissec-tion. Video assistance can be used to improve the visualization Brunicardi_Ch38_p1625-p1704.indd 166001/03/19 11:21 AM 1661THYROID, PARATHYROID, AND ADRENALCHAPTER 38via the small incision. Totally endoscopic approaches also have been described, via the supraclavicular, anterior chest, axillary, and breast approach. The axillary, anterior chest, and breast approaches eliminate the skin incision in the neck but are more invasive. The endoscopic approaches can also be performed with the assistance of robotic techniques. More recently, there have been studies of transoral robotic-assisted


Surgery_Schwartz

Surgery_Schwartz. in the neck but are more invasive. The endoscopic approaches can also be performed with the assistance of robotic techniques. More recently, there have been studies of transoral robotic-assisted thyroidectomy in which the thyroid is approached through the oral cavity.66 These methods are feasible, but clear benefits over the “tradi-tional” open approach via small neck incisions have not been established.4Typically, endoscopic thyroidectomies are performed under general anesthesia. For the axillary approach, a 30-mm skin incision is made in the axilla, and 12-mm and 5-mm trocars are inserted through this incision (Fig. 38-22F). An additional 5-mm trocar is inserted adjacent to the incision. For the anterior chest approach, a 12-mm skin incision is made in the skin of the anterior chest approximately 3 to 5 cm below the border of the ipsilateral clavicle. Two additional 5-mm trocars are inserted by endoscopic guidance below the ipsilateral clavicle, and carbon dioxide (CO2) is then


Surgery_Schwartz

Surgery_Schwartz. approximately 3 to 5 cm below the border of the ipsilateral clavicle. Two additional 5-mm trocars are inserted by endoscopic guidance below the ipsilateral clavicle, and carbon dioxide (CO2) is then insufflated up to a pressure of 4 mmHg to facilitate creation of a working space. The anterior border of the sternocleidomastoid muscle is then separated from the ster-nohyoid muscle to expose the sternothyroid muscle. The thy-roid gland is exposed by splitting the sternothyroid muscle. The lower pole is retracted upward and dissected from the adipose tissue to identify the RLN. As the RLN is exposed, Berry’s liga-ment is exposed and incised with a 5-mm clip or laparoscopic coagulating shears. The upper pole of the thyroid gland is sepa-rated from the cricothyroid muscle, and the external branch of the superior laryngeal nerve can be identified during this maneu-ver. The upper pole of the thyroid gland then is dissected free.Surgical Removal of Intrathoracic Goiter A goiter is consid-ered


Surgery_Schwartz

Surgery_Schwartz. of the superior laryngeal nerve can be identified during this maneu-ver. The upper pole of the thyroid gland then is dissected free.Surgical Removal of Intrathoracic Goiter A goiter is consid-ered mediastinal if at least 50% of the thyroid tissue is located intrathoracically. Mediastinal goiters can be primary or second-ary. Primary mediastinal goiters constitute approximately 1% of all mediastinal goiters and arise from accessory (ectopic) thy-roid tissue located in the chest. These goiters are supplied by intrathoracic blood vessels and do not have any connection to thyroid tissue in the neck. The vast majority of mediastinal goi-ters are, however, secondary mediastinal goiters that arise from downward extension of cervical thyroid tissue along the fascial planes of the neck and derive their blood supply from the supe-rior and inferior thyroid arteries. Virtually all intrathoracic goi-ters can be removed via a cervical incision. Patients who have (a) invasive thyroid cancers, (b)


Surgery_Schwartz

Surgery_Schwartz. their blood supply from the supe-rior and inferior thyroid arteries. Virtually all intrathoracic goi-ters can be removed via a cervical incision. Patients who have (a) invasive thyroid cancers, (b) had previous thyroid operations and may have developed parasitic mediastinal vessels, or (c) pri-mary mediastinal goiters with no thyroid tissue in the neck may require a median sternotomy for removal.49 The chest, however, should be prepared in most cases in the event it is necessary to perform a median sternotomy to control mediastinal bleeding or completely remove an unsuspected invasive cancer. The goiter is approached via a neck incision. The superior pole vessels and the middle thyroid veins are identified and ligated first. Early division of the isthmus helps with subsequent mobilization of the substernal goiter from beneath the sternum. Placement of large 1-0 or 2-0 sutures deep into the goiter, when necessary, helps deliver it. For patients in whom thyroid cancer is suspected or


Surgery_Schwartz

Surgery_Schwartz. of the substernal goiter from beneath the sternum. Placement of large 1-0 or 2-0 sutures deep into the goiter, when necessary, helps deliver it. For patients in whom thyroid cancer is suspected or demonstrated in an intrathoracic gland, attempts should be made to avoid rupture of the thyroid capsule. When sternotomy is indicated, the sternum usually should be divided to the level of the third intercostal space and then laterally on one side at the space between the third and fourth ribs (Fig. 38-23).Central and Lateral Neck Dissection for Nodal Metastases Central compartment (medial to the carotid sheath) lymph nodes frequently are involved in patients with papillary, medullary, and Hürthle cell carcinomas and should be removed at the time of thyroidectomy, preserving the RLNs and parathyroid glands. Central neck dissection is particularly important in patients with medullary and Hürthle cell carcinoma because of the high fre-quency of microscopic tumor spread and because these


Surgery_Schwartz

Surgery_Schwartz. glands. Central neck dissection is particularly important in patients with medullary and Hürthle cell carcinoma because of the high fre-quency of microscopic tumor spread and because these tumors cannot be ablated with 131I. An ipsilateral modified radical neck dissection is indicated in the presence of palpable cervical lymph nodes or prophylactically in some patients with medul-lary carcinoma.A modified radical (functional) neck dissection can be per-formed via the cervical incision used for thyroidectomy, which can be extended laterally (Fig. 38-24A) to the anterior margin of the trapezius muscle. The procedure involves removal of all fibro-fatty tissue along the internal jugular vein (levels II, III, and IV) and the posterior triangle (level V). In contrast to a radical neck dissection, the internal jugular vein, the spinal accessory nerve, the cervical sensory nerves, and the sternoclei-domastoid muscle are preserved unless they are adherent to or invaded by tumor. The procedure


Surgery_Schwartz

Surgery_Schwartz. the internal jugular vein, the spinal accessory nerve, the cervical sensory nerves, and the sternoclei-domastoid muscle are preserved unless they are adherent to or invaded by tumor. The procedure begins by opening the plane between the strap muscles medially and the sternocleidomas-toid muscle laterally. The anterior belly of the omohyoid muscle is retracted laterally, and the dissection is carried posteriorly until the carotid sheath is reached. The internal jugular vein is retracted medially with a vein retractor and the fibro-fatty tissue and lymph nodes are dissected away from it by a combination of sharp and blunt dissection. The lateral dissection is carried along the posterior border of the sternocleidomastoid muscle, remov-ing the tissue from the posterior triangle. The deep dissection plane is the anterior scalenus muscle, the phrenic nerve, the bra-chial plexus, and the medial scalenus muscle. The phrenic nerve is preserved on the scalenus anterior muscle, as are the


Surgery_Schwartz

Surgery_Schwartz. dissection plane is the anterior scalenus muscle, the phrenic nerve, the bra-chial plexus, and the medial scalenus muscle. The phrenic nerve is preserved on the scalenus anterior muscle, as are the cervical sensory nerves in most patients (Fig. 38-24B). Dissection along the spinal accessory nerve superiorly is most important because this is a frequent site of metastatic disease.123Figure 38-23. Conduct of thyroidectomy. Incisions for a partial sternotomy.Brunicardi_Ch38_p1625-p1704.indd 166101/03/19 11:21 AM 1662SPECIFIC CONSIDERATIONSPART IIComplications of Thyroid Surgery Nerves, parathyroids, and surrounding structures are all at risk of injury during thyroidec-tomy. Injury to the RLN may occur by severance, ligation, or traction, but should occur in <1% of patients undergoing thy-roidectomy by experienced surgeons. The RLN is most vulner-able to injury during the last 2 to 3 cm of its course, but also can be damaged if the surgeon is not alert to the possibility of nerve


Surgery_Schwartz

Surgery_Schwartz. thy-roidectomy by experienced surgeons. The RLN is most vulner-able to injury during the last 2 to 3 cm of its course, but also can be damaged if the surgeon is not alert to the possibility of nerve branches and the presence of a nonrecurrent nerve, par-ticularly on the right side. If the injury is recognized intraopera-tively, most surgeons advocate primary reapproximation of the perineurium using nonabsorbable sutures. Approximately 20% of patients are at risk of injury to the external branches of the 123McFee incisionABSpinal accessory n.Phrenic n.Vagus n.Scalenusanticus m.LymphnodesCarotid a. Internaljugular v.Figure 38-24. Conduct of neck dissection. A. Incisions for modified radical neck dissection. B. Anatomic relations of structures identified during a modified radical neck dissection. a. = artery; m. = muscle; n. = nerve.Brunicardi_Ch38_p1625-p1704.indd 166201/03/19 11:21 AM 1663THYROID, PARATHYROID, AND ADRENALCHAPTER 38superior laryngeal nerve, especially if superior


Surgery_Schwartz

Surgery_Schwartz. a. = artery; m. = muscle; n. = nerve.Brunicardi_Ch38_p1625-p1704.indd 166201/03/19 11:21 AM 1663THYROID, PARATHYROID, AND ADRENALCHAPTER 38superior laryngeal nerve, especially if superior pole vessels are ligated en masse. The cervical sympathetic trunk is at risk of injury in invasive thyroid cancers and retroesophageal goiters and may result in Horner’s syndrome. Transient hypocalcemia (from surgical injury or inadvertent removal of parathyroid tis-sue) has been reported in up to 50% of cases, but permanent hypoparathyroidism occurs <2% of the time. Postoperative hypocalcemia is more likely in patients who undergo concomi-tant thyroidectomy and central and lateral neck dissection and in patients with Graves’ disease. Postoperative hematomas or bleeding may also complicate thyroidectomies and rarely neces-sitate emergency reoperation to evacuate the hematoma. Bilat-eral vocal cord dysfunction with airway compromises requires immediate reintubation and tracheostomy. Seromas may


Surgery_Schwartz

Surgery_Schwartz. and rarely neces-sitate emergency reoperation to evacuate the hematoma. Bilat-eral vocal cord dysfunction with airway compromises requires immediate reintubation and tracheostomy. Seromas may need aspiration to relieve patient discomfort. Wound cellulitis and infection and injury to surrounding structures, such as the carotid artery, jugular vein, and esophagus, are infrequent.PARATHYROIDHistorical BackgroundIn 1849, the curator of the London Zoological Gardens, Sir Richard Owen, provided the first accurate description of the normal parathyroid gland after autopsy examination of an Indian rhinoceros. However, human parathyroids were not grossly and microscopically described until 1879 by Ivar Sandström, a med-ical student in Uppsala, Sweden. He suggested that these glands be named the glandulae parathyroideae, although their function was not known.The association of HPT and the bone disease osteitis fibrosa cystica (described by von Recklinghausen) was recog-nized in 1903. Calcium


Surgery_Schwartz

Surgery_Schwartz. glandulae parathyroideae, although their function was not known.The association of HPT and the bone disease osteitis fibrosa cystica (described by von Recklinghausen) was recog-nized in 1903. Calcium measurement became possible in 1909, and the association between serum calcium levels and the para-thyroid glands was established. The first successful parathyroid-ectomy was performed in 1925 by Felix Mandl on a 38-year-old man who had severe bone pain secondary to advanced osteitis fibrosa cystica. The patient’s condition dramatically improved after the operation, and he lived for another 7 years before dying of recurrent HPT or renal failure. In 1926, the first parathyroid operation was performed at Massachusetts General Hospital. Edward Churchill, assisted by an intern named Oliver Cope, operated on the famous sea captain Charles Martell for severe primary HPT (PHPT). It was not until his seventh operation, which included total thyroidectomy, that an ectopic adenoma was found


Surgery_Schwartz

Surgery_Schwartz. Cope, operated on the famous sea captain Charles Martell for severe primary HPT (PHPT). It was not until his seventh operation, which included total thyroidectomy, that an ectopic adenoma was found substernally. Unfortunately, Captain Martell died 6 weeks later, likely due to laryngeal spasm and complications of renal stones and ureteral obstruction. The first successful para-thyroidectomy for HPT in the United States was performed on a 56-year-old woman in 1928 by Isaac Y. Olch at the Barnes Hospital in St. Louis, Missouri. At operation, a parathyroid ade-noma was found attached to the left lower lobe of the thyroid gland. Postoperatively, the patient developed tetany, requiring lifelong supplemental calcium.EmbryologyIn humans, the superior parathyroid glands are derived from the fourth branchial pouch, which also gives rise to the thyroid gland. The third branchial pouches give rise to the inferior para-thyroid glands and the thymus (Fig. 38-25). The parathyroids remain closely


Surgery_Schwartz

Surgery_Schwartz. branchial pouch, which also gives rise to the thyroid gland. The third branchial pouches give rise to the inferior para-thyroid glands and the thymus (Fig. 38-25). The parathyroids remain closely associated with their respective branchial pouch derivatives. The position of normal superior parathyroid glands is more consistent, with 80% of these glands being found near the posterior aspect of the upper and middle thyroid lobes, at the level of the cricoid cartilage. Approximately 1% of normal upper glands may be found in the paraesophageal or retro-esophageal space. Enlarged superior glands may descend in the tracheoesophageal groove and come to lie caudal to the inferior glands. Truly ectopic superior parathyroid glands are rare, but they may be found in the middle or posterior mediastinum or in the aortopulmonary window.51 As the embryo matures, the thy-mus and inferior parathyroids migrate together caudally in the neck. The most common location for inferior glands is within a


Surgery_Schwartz

Surgery_Schwartz. or in the aortopulmonary window.51 As the embryo matures, the thy-mus and inferior parathyroids migrate together caudally in the neck. The most common location for inferior glands is within a distance of 1 cm from a point centered where the inferior thyroid artery and RLN cross. Approximately 15% of inferior glands Parathyroid IIIForamen caecumThyroglossal ductMedian thyroidThymusTracheaEsophagusFifth branchialpouchFourthbranchialpouchThirdbranchialpouchParathyroid IVUltimobranchialbodyMedian thyroidLateralthyroid or ultimobranchial bodyEsophagusParathyroid IVParathyroid IIIThymusABFigure 38-25. Parathyroid embryology. Figure demonstrates a schematic view of the pharynx of an 8to 10-mm embryo (A) and locations of the thyroid, parathyroid, and thymic tissues in a 13to 14-mm embryo (B). The lower parathyroids are derived from the third branchial pouch and migrate with the thymus, whereas the upper parathyroids are derived from the fourth branchial pouch and lie in close proximity to the


Surgery_Schwartz

Surgery_Schwartz. lower parathyroids are derived from the third branchial pouch and migrate with the thymus, whereas the upper parathyroids are derived from the fourth branchial pouch and lie in close proximity to the ultimobranchial bodies. (Reproduced with permission from Randolph G: Surgery of the Thyroid and Parathyroid Glands. Philadelphia, PA: Elsevier/Saunders; 2003.)Brunicardi_Ch38_p1625-p1704.indd 166301/03/19 11:21 AM 1664SPECIFIC CONSIDERATIONSPART IIare found in the thymus. The position of the inferior glands, however, tends to be more variable due to their longer migratory path. Undescended inferior glands may be found near the skull base, angle of the mandible, or superior to the upper parathyroid glands along with an undescended thymus. The frequency of intrathyroidal glands is about 2%.Anatomy and HistologyMost patients have four parathyroid glands. The superior glands usually are dorsal to the RLN at the level of the cricoid cartilage, whereas the inferior parathyroid glands are


Surgery_Schwartz

Surgery_Schwartz. and HistologyMost patients have four parathyroid glands. The superior glands usually are dorsal to the RLN at the level of the cricoid cartilage, whereas the inferior parathyroid glands are located ventral to the nerve. Normal parathyroid glands are gray and semitransparent in newborns but appear golden yellow to light brown in adults. Parathyroid color depends on cellularity, fat content, and vas-cularity. Moreover, they often are embedded in and sometimes difficult to discern from surrounding fat. Normal parathyroid glands are located in loose tissue or fat and are ovoid. They measure up to 7 mm in size and weigh approximately 40 to 50 mg each. Parathyroid glands usually derive their blood supply from branches of the inferior thyroid artery, although branches from the superior thyroid artery supply at least 20% of upper glands. Branches from the thyroidea ima, and vessels to the trachea, esophagus, larynx, and mediastinum may also be found. The parathyroid glands drain


Surgery_Schwartz

Surgery_Schwartz. thyroid artery supply at least 20% of upper glands. Branches from the thyroidea ima, and vessels to the trachea, esophagus, larynx, and mediastinum may also be found. The parathyroid glands drain ipsilaterally by the superior, middle, and inferior thyroid veins.Akerström and colleagues,67 in an autopsy series of 503 cadavers, found four parathyroid glands in 84% of cases. Super-numerary glands were present in 13% of patients, most com-monly in the thymus. Only 3% of patients had less than four glands. Similar results were obtained in other dissection studies of 428 human subjects by Gilmour who reported a 6.7% inci-dence of supernumerary glands.68Histologically, parathyroid glands are composed of chief cells and oxyphil cells arranged in trabeculae, within a stroma composed primarily of adipose cells (Fig. 38-26). The parathy-roid glands of infants and children are composed mainly of chief cells, which produce parathyroid hormone (PTH). Acidophilic, mitochondria-rich oxyphil cells are


Surgery_Schwartz

Surgery_Schwartz. cells (Fig. 38-26). The parathy-roid glands of infants and children are composed mainly of chief cells, which produce parathyroid hormone (PTH). Acidophilic, mitochondria-rich oxyphil cells are derived from chief cells, can be seen around puberty, and increase in numbers in adult-hood. A third group of cells, known as water-clear cells, also are derived from chief cells, are present in small numbers, and are rich in glycogen. Although most oxyphil and water-clear Figure 38-26. Normal parathyroid histology showing chief cells interspersed with adipose cells.cells retain the ability to secrete PTH, their functional signifi-cance is not known.Parathyroid Physiology and Calcium HomeostasisCalcium is the most abundant cation in human beings and has several crucial functions. Extracellular calcium levels are 10,000-fold higher than intracellular levels, and both are tightly controlled. Extracellular calcium is important for excitationcontraction coupling in muscle tissues, synaptic


Surgery_Schwartz

Surgery_Schwartz. calcium levels are 10,000-fold higher than intracellular levels, and both are tightly controlled. Extracellular calcium is important for excitationcontraction coupling in muscle tissues, synaptic transmission in the nervous system, coagulation, and secretion of other hormones. Intracellular calcium is an important second messenger regulat-ing cell division, motility, membrane trafficking, and secretion. Calcium is absorbed from the small intestine in its inorganic form. Calcium fluxes in the steady state are depicted in Fig. 38-27.Extracellular calcium (900 mg) accounts for only 1% of the body’s calcium stores, the majority of which is sequestered in the skeletal system. Approximately 50% of the serum cal-cium is in the ionized form, which is the active component. The remainder is bound to albumin (40%) and organic anions such as phosphate and citrate (10%). The total serum calcium levels range from 8.5 to 10.5 mg/dL (2.1 to 2.6 mmol/L), and ionized calcium levels range from 4.4 to


Surgery_Schwartz

Surgery_Schwartz. to albumin (40%) and organic anions such as phosphate and citrate (10%). The total serum calcium levels range from 8.5 to 10.5 mg/dL (2.1 to 2.6 mmol/L), and ionized calcium levels range from 4.4 to 5.2 mg/dL (1.1 to 1.3 mmol/L). Both concentrations are tightly regulated. The total serum calcium level must always be considered in its rela-tionship to plasma protein levels, especially serum albumin. For each gram per deciliter of alteration of serum albumin above or below 4.0 mg/dL, there is a 0.8 mg/dL increase or decrease in protein-bound calcium and, thus, in total serum calcium levels. Total and, particularly, ionized calcium levels are influenced by various hormone systems.Parathyroid Hormone. The parathyroid cells rely on a G-protein–coupled membrane receptor, designated the calcium-sensing receptor (CASR), to regulate PTH secretion by sensing extracellular calcium levels69 (Fig. 38-28). PTH secretion also is stimulated by low levels of 1,25-dihydroxy vitamin D, cat-echolamines,


Surgery_Schwartz

Surgery_Schwartz. receptor (CASR), to regulate PTH secretion by sensing extracellular calcium levels69 (Fig. 38-28). PTH secretion also is stimulated by low levels of 1,25-dihydroxy vitamin D, cat-echolamines, and hypomagnesemia. The PTH gene is located on chromosome 11. PTH is synthesized in the parathyroid gland as a precursor hormone preproPTH, which is cleaved first to pro-PTH and then to the final 84-amino-acid PTH. Secreted PTH has a half-life of 2 to 4 minutes. In the liver, PTH is metabolized into the active N-terminal component and the relatively inactive C-terminal fraction. The C-terminal component is excreted by the kidneys and accumulates in chronic renal failure.PTH functions to regulate calcium levels via its actions on three target organs, the bone, kidney, and gut. PTH increases the resorption of bone by stimulating osteoclasts and promotes the release of calcium and phosphate into the circulation. At the kidney, calcium is primarily absorbed in concert with sodium in the proximal


Surgery_Schwartz

Surgery_Schwartz. of bone by stimulating osteoclasts and promotes the release of calcium and phosphate into the circulation. At the kidney, calcium is primarily absorbed in concert with sodium in the proximal convoluted tubule, but fine adjustments occur more distally. PTH acts to limit calcium excretion at the dis-tal convoluted tubule via an active transport mechanism. PTH also inhibits phosphate reabsorption (at the proximal convoluted tubule) and bicarbonate reabsorption. It also inhibits the Na+/H+ antiporter, which results in a mild metabolic acidosis in hyper-parathyroid states. PTH and hypophosphatemia also enhance 1-hydroxylation of 25-hydroxyvitamin D, which is responsible for its indirect effect of increasing intestinal calcium absorption.Calcitonin. Calcitonin is produced by thyroid C cells and func-tions as an antihypercalcemic hormone by inhibiting osteoclast-mediated bone resorption. Calcitonin production is stimulated Brunicardi_Ch38_p1625-p1704.indd 166401/03/19 11:21 AM


Surgery_Schwartz

Surgery_Schwartz. cells and func-tions as an antihypercalcemic hormone by inhibiting osteoclast-mediated bone resorption. Calcitonin production is stimulated Brunicardi_Ch38_p1625-p1704.indd 166401/03/19 11:21 AM 1665THYROID, PARATHYROID, AND ADRENALCHAPTER 38Figure 38-27. Calcium balance and fluxes in a normal human. Solid arrows depict a direct effect, whereas dashed arrows depict an indirect effect. The thickness of the arrows is representative of the magnitude of the flux. ECF = extracellular fluid; PTH = parathyroid hormone; VIT. = vitamin. (Reproduced with permission from Felig P, Frohman L: Endocrinology and Metabolism. New York, NY: McGraw-Hill Education; 2001.)PTHPTHVIT. DECFCALCIUM900 mgKidneyUrine0.15 0.3 g900 1400 gBone0.25 0.5 g0.25 0.5 g0.25 0.5 g0.1 0.2 g0.4 1.5 g0.35 1.0 gVIT. DPTHby calcium and pentagastrin and also by catecholamines, chole-cystokinin, and glucagon. When administered intravenously to experimental animals, it produces hypocalcemia. At the kidney, calcitonin


Surgery_Schwartz

Surgery_Schwartz. calcium and pentagastrin and also by catecholamines, chole-cystokinin, and glucagon. When administered intravenously to experimental animals, it produces hypocalcemia. At the kidney, calcitonin increases phosphate excretion by inhibiting its reab-sorption. Calcitonin plays a minimal, if any, role in the regula-tion of calcium levels in humans. However, it is very useful as a marker of MTC and in treating acute hypercalcemic crisis.Vitamin D. Vitamin D refers to vitamin D2 and vitamin D3, both of which are produced by photolysis of naturally occurring ste-rol precursors. Vitamin D2 is available commercially in pharma-ceutical preparations, whereas vitamin D3 is the most important physiologic compound and is produced from 7-dehydrocholes-terol, which is found in the skin. Vitamin D is metabolized in the liver to its primary circulating form, 25-hydroxyvitamin D. Further hydroxylation in the kidney results in 1,25-dihydroxy vitamin D, which is the most metabolically active form of


Surgery_Schwartz

Surgery_Schwartz. in the liver to its primary circulating form, 25-hydroxyvitamin D. Further hydroxylation in the kidney results in 1,25-dihydroxy vitamin D, which is the most metabolically active form of vitamin D. Vitamin D stimulates the absorption of calcium and phosphate from the gut and the resorption of calcium from the bone.HyperparathyroidismHyperfunction of the parathyroid glands may be classified as primary, secondary, or tertiary. PHPT arises from increased PTH production from abnormal parathyroid glands and results from a disturbance of normal feedback control exerted by serum calcium. Elevated PTH levels may also occur as a compensa-tory response to hypocalcemic states resulting from chronic renal failure or GI malabsorption of calcium. This secondary HPT can be reversed by correction of the underlying problem (e.g., kidney transplantation for chronic renal failure). However, chronically stimulated glands may occasionally become autono-mous, resulting in persistence or recurrence of


Surgery_Schwartz

Surgery_Schwartz. the underlying problem (e.g., kidney transplantation for chronic renal failure). However, chronically stimulated glands may occasionally become autono-mous, resulting in persistence or recurrence of hypercalcemia after successful renal transplantation, resulting in tertiary HPT.Primary Hyperparathyroidism. PHPT is a common dis-order, affecting 100,000 individuals annually in the United States. PHPT occurs in 0.1% to 0.3% of the general population and is more common in women (1:500) than in men (1:2000). Increased PTH production leads to hypercalcemia via increased GI absorption of calcium, increased production of vitamin D3, and reduced renal calcium clearance. PHPT is characterized by increased parathyroid cell proliferation and PTH secretion that is independent of calcium levels.Etiology The exact cause of PHPT is unknown, although exposure to low-dose therapeutic ionizing radiation and familial predisposition account for some cases. Various diets and inter-mittent exposure to


Surgery_Schwartz

Surgery_Schwartz. exact cause of PHPT is unknown, although exposure to low-dose therapeutic ionizing radiation and familial predisposition account for some cases. Various diets and inter-mittent exposure to sunshine may also be related. Other causes include renal leak of calcium and declining renal function with age as well as alteration in the sensitivity of parathyroid glands to suppression by calcium. The latency period for development of PHPT after radiation exposure is longer than that for the development of thyroid tumors, with most cases occurring 30 to 40 years after exposure. Patients who have been exposed to radiation have similar clinical presentations and calcium levels when compared to patients without a history of radiation expo-sure. However, the former tends to have higher PTH levels and a higher incidence of concomitant thyroid neoplasms. Lithium therapy has been known to shift the set point for PTH secre-tion in parathyroid cells, thereby resulting in elevated PTH lev-els and mild


Surgery_Schwartz

Surgery_Schwartz. a higher incidence of concomitant thyroid neoplasms. Lithium therapy has been known to shift the set point for PTH secre-tion in parathyroid cells, thereby resulting in elevated PTH lev-els and mild hypercalcemia. Lithium stimulates the growth of abnormal parathyroid glands in vitro and also in susceptible patients in vivo. PHPT results from the enlargement of a single gland or parathyroid adenoma in approximately 80% of cases, multiple adenomas or hyperplasia in 15% to 20% of patients, and parathyroid carcinoma in 1% of patients. Existence of two enlarged glands or double adenomas is supported by bio-chemical (calcium and PTH), intraoperative PTH (IOPTH), molecular, and histologic data. This entity is less common in younger patients but accounts for up to 10% of older patients with PHPT. It should be emphasized that when more than one abnormal parathyroid gland is identified preoperatively or intra-operatively, the patient has hyperplasia (all glands abnormal) until proven


Surgery_Schwartz

Surgery_Schwartz. with PHPT. It should be emphasized that when more than one abnormal parathyroid gland is identified preoperatively or intra-operatively, the patient has hyperplasia (all glands abnormal) until proven otherwise.Genetics Most cases of PHPT are sporadic. However, PHPT also occurs within the spectrum of a number of inherited Brunicardi_Ch38_p1625-p1704.indd 166501/03/19 11:21 AM 1666SPECIFIC CONSIDERATIONSPART IIdisorders such as MEN1, MEN2A, isolated familial HPT, and familial HPT with jaw-tumor syndrome. All of these syndromes are inherited in an autosomal dominant fashion. PHPT is the earliest and most common manifestation of MEN1 and develops in 80% to 100% of patients by age 40 years old. These patients also are prone to pancreatic neuroendocrine tumors and pitu-itary adenomas and, less commonly, to adrenocortical tumors, lipomas, skin angiomas, and carcinoid tumors of the bronchus, thymus, or stomach. About 50% of patients develop gastrino-mas, which often are multiple and


Surgery_Schwartz

Surgery_Schwartz. less commonly, to adrenocortical tumors, lipomas, skin angiomas, and carcinoid tumors of the bronchus, thymus, or stomach. About 50% of patients develop gastrino-mas, which often are multiple and metastatic at diagnosis. Insu-linomas develop in 10% to 15% of cases, whereas many patients have nonfunctional pancreatic endocrine tumors. Prolactinomas occur in 10% to 50% of MEN1 patients and constitute the most common pituitary lesion. MEN1 has been shown to result from germline mutations in the MEN1 gene, a tumor suppressor gene located on chromosome 11q12-13 that encodes menin, a protein that is postulated to interact with the transcription factors JunD and nuclear factor-κB in the nucleus, in addition to replication protein A and other proteins.70 Most MEN1 mutations result in a nonfunctional protein and are scattered throughout the translated nine exons of the gene. This makes presymptomatic screening for mutation carriers difficult. MEN1 mutations also have been found in kindreds


Surgery_Schwartz

Surgery_Schwartz. protein and are scattered throughout the translated nine exons of the gene. This makes presymptomatic screening for mutation carriers difficult. MEN1 mutations also have been found in kindreds initially suspected to represent isolated famil-ial HPT. HPT develops in about 20% of patients with MEN2A and generally is less severe. MEN2A is caused by germline mutations of the RET proto-oncogene located on chromosome 10. In contrast to MEN1, genotype-phenotype correlations have been noted in this syndrome in that individuals with mutations at codon 634 are more likely to develop HPT. Patients with the familial HPT with jaw-tumor syndrome have an increased predisposition to parathyroid carcinoma. This syndrome maps to a tumor suppressor locus HRPT2 (CDC73 or parafibromin) on chromosome 1. Patients belonging to isolated HPT kindreds also appear to demonstrate linkage to HRPT2. More recently, a subset of patients with MEN-1 phenotype in the absence of MENIN mutations were found to harbor


Surgery_Schwartz

Surgery_Schwartz. belonging to isolated HPT kindreds also appear to demonstrate linkage to HRPT2. More recently, a subset of patients with MEN-1 phenotype in the absence of MENIN mutations were found to harbor inactivating mutation NH2Ca2+Ca2+Ca2+[Ca2+]iCASRPKCCOOHG proteins PLCIns (1,4,5) P3Regulation of PTHParathyroid cellSystemic effectsKidney25(OH)D3LiverVitamin D1,25(OH)2D3BoneSmall intestineERCa2+Ca2+Ca2+Ca2+Ca2+Ca2+Figure 38-28. Regulation of calcium homeostasis. The calcium-sensing receptor (CASR) is expressed on the surface of the parathyroid cell and senses fluctuations in the concentration of extracellular calcium. Activation of the receptor is thought to increase intracellular cal-cium levels, which, in turn, inhibit parathyroid hormone (PTH) secretion via posttranslational mechanisms. Increased PTH secretion leads to an increase in serum calcium levels by increasing bone resorption and enhancing renal calcium reabsorption. PTH also stimulates renal 1-α-hydroxylase activity, leading to an


Surgery_Schwartz

Surgery_Schwartz. PTH secretion leads to an increase in serum calcium levels by increasing bone resorption and enhancing renal calcium reabsorption. PTH also stimulates renal 1-α-hydroxylase activity, leading to an increase in 1,25-dihydroxy vitamin D, which also exerts a negative feedback on PTH secretion. PKC = protein kinase C; PLC = phospholipase C. (Reproduced with permission from Carling T: Molecular pathology of parathyroid tumors, Trends Endocrinol Metab. 2001 Mar;12(2):53-58.)Brunicardi_Ch38_p1625-p1704.indd 166601/03/19 11:21 AM 1667THYROID, PARATHYROID, AND ADRENALCHAPTER 38in the tumor suppressor gene CDKN1B on chromosome 12p13 and given the diagnosis of MEN4.71,72 CDKN1B encodes p27kip1, which is involved in cyclin D1 signaling.Approximately 25% to 40% of sporadic parathyroid ade-nomas and some hyperplastic parathyroid glands have loss of heterozygosity (LOH) at 11q13, the site of the MEN1 gene. The parathyroid adenoma 1 oncogene (PRAD1 or CCND1), which encodes cyclin D1, a cell cycle


Surgery_Schwartz

Surgery_Schwartz. some hyperplastic parathyroid glands have loss of heterozygosity (LOH) at 11q13, the site of the MEN1 gene. The parathyroid adenoma 1 oncogene (PRAD1 or CCND1), which encodes cyclin D1, a cell cycle control protein, is overexpressed in about 18% of parathyroid adenomas. This was demonstrated to result from a rearrangement on chromosome 11 that places the PRAD1 gene under the control of the PTH promoter. Sporadic parathyroid tumors also appear to carry alterations in cyclin dependent kinase inhibitor encoding genes, in particular somatic inactivating mutations of CDKN1B. Other chromosomal regions deleted in parathyroid adenomas and possibly reflecting loss of tumor suppressor genes include 1p, 6q, and 15q, whereas ampli-fied regions suggesting oncogenes have been identified at 16p and 19p. RET mutations are rare in sporadic parathyroid tumors. Sporadic parathyroid cancers are characterized by uniform loss of the tumor suppressor gene RB, which is involved in cell cycle regulation, and


Surgery_Schwartz

Surgery_Schwartz. RET mutations are rare in sporadic parathyroid tumors. Sporadic parathyroid cancers are characterized by uniform loss of the tumor suppressor gene RB, which is involved in cell cycle regulation, and 60% have HRPT2 (CDC73) mutations. These alterations are rare in benign parathyroid tumors and may have implications for diagnosis. The p53 tumor suppressor gene is also inactivated in a subset (30%) of parathyroid carcinomas.73Clinical Manifestations Patients with PHPT formerly pre-sented with the “classic” pentad of symptoms (i.e., kidney stones, painful bones, abdominal groans, psychic moans, and fatigue overtones). With the advent and widespread use of auto-mated blood analyzers in the early 1970s, there has been an alteration in the “typical” patient with PHPT. They are more likely to be minimally symptomatic or asymptomatic. Currently, most patients present with weakness, fatigue, polydipsia, poly-uria, nocturia, bone and joint pain, constipation, decreased appe-tite, nausea,


Surgery_Schwartz

Surgery_Schwartz. to be minimally symptomatic or asymptomatic. Currently, most patients present with weakness, fatigue, polydipsia, poly-uria, nocturia, bone and joint pain, constipation, decreased appe-tite, nausea, heartburn, pruritus, depression, and memory loss. Patients with PHPT also tend to score lower than healthy controls when assessed by general multidimensional health assessment tools such as the Medical Outcomes Study Short-Form Health Survey (SF-36) and other specific questionnaires. Furthermore, these symptoms and signs improve in most, but certainly not all, patients after parathyroidectomy. Truly “asymptomatic” PHPT appears to be rare, occurring in <5% of patients, as determined by prospectively administered questionnaires. Complications of PHPT are described in the following section.Renal Disease. Approximately 80% of patients with PHPT have some degree of renal dysfunction or symptoms. Kidney stones were previously reported in up to 80% of patients but now occur in about 20% to 25%.


Surgery_Schwartz

Surgery_Schwartz. Disease. Approximately 80% of patients with PHPT have some degree of renal dysfunction or symptoms. Kidney stones were previously reported in up to 80% of patients but now occur in about 20% to 25%. The calculi are typically com-posed of calcium phosphate or oxalate. In contrast, PHPT is found to be the underlying disorder in only 3% of patients pre-senting with nephrolithiasis. Nephrocalcinosis, which refers to renal parenchymal calcification, is found in <5% of patients and is more likely to lead to renal dysfunction. Chronic hypercalce-mia also can impair concentrating ability, thereby resulting in polyuria, polydipsia, and nocturia. The incidence of hyperten-sion is variable but has been reported to occur in up to 50% of patients with PHPT. Hypertension appears to be more common in older patients and correlates with the magnitude of renal dys-function and, in contrast to other symptoms, is least likely to improve after parathyroidectomy.Bone Disease. Bone disease, including


Surgery_Schwartz

Surgery_Schwartz. in older patients and correlates with the magnitude of renal dys-function and, in contrast to other symptoms, is least likely to improve after parathyroidectomy.Bone Disease. Bone disease, including osteopenia, osteoporo-sis, and osteitis fibrosa cystica, is found in about 15% of patients with PHPT. Increased bone turnover, as found in patients with osteitis fibrosa cystica, can be determined by documenting an elevated blood alkaline phosphatase level. Advanced PHPT with osteitis fibrosa cystica now occurs in <5% of patients. It has pathognomonic radiologic findings, which are best seen on X-rays of the hands and are characterized by subperiosteal resorption (most apparent on the radial aspect of the middle pha-lanx of the second and third fingers), bone cysts, and tufting of the distal phalanges (Fig. 38-29). The skull also may be affected and appears mottled with a loss of definition of the inner and outer cortices. Brown or osteoclastic tumors and bone cysts also may be present.


Surgery_Schwartz

Surgery_Schwartz. phalanges (Fig. 38-29). The skull also may be affected and appears mottled with a loss of definition of the inner and outer cortices. Brown or osteoclastic tumors and bone cysts also may be present. Severe bone disease, resulting in bone pain and tenderness and/or pathologic fractures, is rarely observed nowa-days. However, reductions of bone mineral density (BMD) with osteopenia and osteoporosis are more common. Patients with normal serum alkaline phosphatase levels almost never have clinically apparent osteitis fibrosa cystica. HPT typically results in a loss of bone mass at sites of cortical bone such as the radius and relative preservation of cancellous bone such as that located at the vertebral bodies. Patients with PHPT, however, also may Figure 38-29. X-ray of the hand showing subperiosteal bone resorption most apparent along the radial aspect of the middle pha-lanx, characteristic of osteitis fibrosa cystica.Brunicardi_Ch38_p1625-p1704.indd 166701/03/19 11:21 AM


Surgery_Schwartz

Surgery_Schwartz. subperiosteal bone resorption most apparent along the radial aspect of the middle pha-lanx, characteristic of osteitis fibrosa cystica.Brunicardi_Ch38_p1625-p1704.indd 166701/03/19 11:21 AM 1668SPECIFIC CONSIDERATIONSPART IIhave osteoporosis of the lumbar spine that improves dramati-cally following parathyroidectomy. Fractures also occur more frequently in patients with PHPT, and the incidence of fractures also decreases after parathyroidectomy. Bone disease correlates with serum PTH and vitamin D levels.Gastrointestinal Complications. PHPT has been associated with peptic ulcer disease. In experimental animals, hypergastrin-emia has been shown to result from PTH infusion into blood ves-sels supplying the stomach, independent of its effects on serum calcium. An increased incidence of pancreatitis also has been reported in patients with PHPT, although this appears to occur only in patients with profound hypercalcemia (Ca2+ ≥12.5 mg/dL). Patients with PHPT also have an increased


Surgery_Schwartz

Surgery_Schwartz. pancreatitis also has been reported in patients with PHPT, although this appears to occur only in patients with profound hypercalcemia (Ca2+ ≥12.5 mg/dL). Patients with PHPT also have an increased incidence of choleli-thiasis, presumably due to an increase in biliary calcium, which leads to the formation of calcium bilirubinate stones.Neuropsychiatric Complications. Severe hypercalcemia may lead to various neuropsychiatric manifestations such as florid psy-chosis, obtundation, or coma. Other findings such as depression, anxiety, and fatigue are more commonly observed in patients with only mild hypercalcemia. The etiology of these symptoms is not known. Studies demonstrate that levels of certain neu-rotransmitters (monoamine metabolites 5-hydroxyindoleacetic acid and homovanillic acid) are reduced in the cerebrospi-nal fluid of patients with PHPT when compared to controls. Electroencephalogram abnormalities also occur in patients with primary and secondary HPT and normalize following


Surgery_Schwartz

Surgery_Schwartz. reduced in the cerebrospi-nal fluid of patients with PHPT when compared to controls. Electroencephalogram abnormalities also occur in patients with primary and secondary HPT and normalize following parathyroidectomy.Other Features. PHPT also can lead to fatigue and muscle weakness, which is prominent in the proximal muscle groups. Although the exact etiology of this finding is not known, muscle biopsy studies show that weakness results from a neuropathy, rather than a primary myopathic abnormality. Patients with HPT also have an increased incidence of chondrocalcinosis, gout, and pseudogout, with deposition of uric acid and calcium pyro-phosphate crystals in the joints. Calcification at ectopic sites such as blood vessels, cardiac valves, and skin also has been reported, as has hypertrophy of the left ventricle independent of the presence of hypertension. There is also evidence for subtle cardiovascular manifestations in mild disease, such as changes in endothelial function, increased


Surgery_Schwartz

Surgery_Schwartz. of the left ventricle independent of the presence of hypertension. There is also evidence for subtle cardiovascular manifestations in mild disease, such as changes in endothelial function, increased vascular stiffness, and perhaps subtle diastolic dysfunction. Several large studies from Europe also suggest that PHPT is associated with increased death rates from cardiovascular disease and cancer even in patients with mild HPT, although this finding was not substantiated in North American studies.Physical Findings Parathyroid tumors are seldom palpable, except in patients with profound hypercalcemia or parathyroid cancer. A palpable neck mass in a patient with PHPT is more likely to be thyroid in origin or a parathyroid cancer. Patients also may demonstrate evidence of band keratopathy, a depo-sition of calcium in Bowman’s membrane just inside the iris of the eye. This nonspecific condition generally is caused by chronic eye diseases such as uveitis, glaucoma, and trauma but also may


Surgery_Schwartz

Surgery_Schwartz. depo-sition of calcium in Bowman’s membrane just inside the iris of the eye. This nonspecific condition generally is caused by chronic eye diseases such as uveitis, glaucoma, and trauma but also may occur in the presence of conditions associated with high calcium or phosphate levels. Fibro-osseous jaw tumors, and/or the presence of familial disease in patients with PHPT and jaw tumors, if present, should alert the physician to the pos-sibility of parathyroid carcinoma.Differential Diagnosis Hypercalcemia may be caused by a multitude of conditions, as listed in Table 38-9. PHPT and malignancy account for >90% of all cases of hypercalcemia. PHPT is more common in the outpatient setting, whereas malig-nancy is the leading cause of hypercalcemia in hospitalized patients. PHPT can virtually always be distinguished from other diseases causing hypercalcemia by a combination of history, physical examination, and appropriate laboratory investigations.Hypercalcemia associated with malignancy


Surgery_Schwartz

Surgery_Schwartz. always be distinguished from other diseases causing hypercalcemia by a combination of history, physical examination, and appropriate laboratory investigations.Hypercalcemia associated with malignancy includes three distinct syndromes. Although bone metastases may cause hypercalcemia, patients with solid tumors of the lung, breast, kidney, head and neck, and ovary often have humoral hyper-calcemia of malignancy, without any associated bony metas-tases. In addition, hypercalcemia also may be associated with hematologic malignancies such as multiple myeloma. Humoral hypercalcemia of malignancy is known to be mediated primar-ily by PTH-related peptide (PTHrP), which also plays a role in the hypercalcemia associated with bone metastases and multiple myeloma.Thiazide diuretics cause hypercalcemia by decreasing renal clearance of calcium. This corrects in normal patients within days to weeks after discontinuing the diuretic, but patients with PHPT continue to be hypercalcemic. Thiazide


Surgery_Schwartz

Surgery_Schwartz. by decreasing renal clearance of calcium. This corrects in normal patients within days to weeks after discontinuing the diuretic, but patients with PHPT continue to be hypercalcemic. Thiazide diuretics can, therefore, exacerbate underlying PHPT and can be used to unmask PHPT in patients with borderline hyper-calcemia. Familial hypocalciuric hypercalcemia 1 (FHH1) is a rare autosomal dominant condition with nearly 100% pen-etrance and results from inherited heterozygous mutations in the CASR gene located on chromosome 3.54 Homozygous germline mutations at this locus result in neonatal severe pri-mary hyperparathyroidism and calcemia, a condition that can rapidly prove fatal. Patients with FHH1 generally have lifelong hypercalcemia, which is not corrected by parathyroidectomy. A milder form of the disease known as familial hypercalciu-ric hypercalcemia results from germline inactivating mutations in the intracytoplasmic tail domain of the CaSR gene. These patients have an appropriate


Surgery_Schwartz

Surgery_Schwartz. of the disease known as familial hypercalciu-ric hypercalcemia results from germline inactivating mutations in the intracytoplasmic tail domain of the CaSR gene. These patients have an appropriate hypercalciuric response to elevated calcium and PTH in addition to hypermagnesemia and hyper-phosphaturia. Some cases benefit from parathyroidectomy. Recently two new types of FHH (2 and 3) have been described. These are associated with germline inactivating mutations of GNA11(19p13.3) and AP2S1(19q12.2) genes. Both mutations cause hypocalciuric hypercalcemia through aberrant inactiva-tion of CaSR signaling. Although clinical presentation in FHH2 is similar to FHH1, those with FHH3 tend to have higher PTH levels and osteomalacia.71Table 38-9Differential diagnosis of hypercalcemiaHyperparathyroidismMalignancy—hematologic (multiple myeloma), solid tumors (due to PTHrP)Endocrine diseases—hyperthyroidism, Addisonian crisis, VIPomaGranulomatous diseases—sarcoidosis, tuberculosis, berylliosis,


Surgery_Schwartz

Surgery_Schwartz. (multiple myeloma), solid tumors (due to PTHrP)Endocrine diseases—hyperthyroidism, Addisonian crisis, VIPomaGranulomatous diseases—sarcoidosis, tuberculosis, berylliosis, histoplasmosisMilk-alkali syndromeDrugs—thiazide diuretics, lithium, vitamin A or D intoxicationFamilial hypocalciuric hypercalcemiaPaget’s diseaseImmobilizationPTHrP = parathyroid hormone-related protein; VIP = vasoactive intestinal peptide.Brunicardi_Ch38_p1625-p1704.indd 166801/03/19 11:21 AM 1669THYROID, PARATHYROID, AND ADRENALCHAPTER 38Coexisting primaryhyperparathyroidismand malignancyIntact PTHNormalrangeHypo-parathyroidismPrimaryhyper-parathyroidismLimit ofdetectionHypercalcemiaassociatedwith malignancy968634Intact PTH (pg/mL of hPTH [1-84])Normal50020015010050Figure 38-30. Intact parathyroid hormone (PTH) measurement allows differentiation between the various causes of hypercalcemia. (Reproduced with permission from Endres DB, Villanueva R, Sharp CF, et al. Measurement of parathyroid hormone,


Surgery_Schwartz

Surgery_Schwartz. (PTH) measurement allows differentiation between the various causes of hypercalcemia. (Reproduced with permission from Endres DB, Villanueva R, Sharp CF, et al. Measurement of parathyroid hormone, Endocrinol Metab Clin North Am. 1989 Sep;18(3):611-629.)Hypercalcemia also is found in approximately 10% of patients with sarcoidosis secondary to increased 25-hydroxy vitamin D 1-hydroxylase activity in lymphoid tissue and pul-monary macrophages, which is not subject to inhibitory feed-back control by serum calcium. Thyroid hormone also has bone-resorption properties, thus causing hypercalcemia in thy-rotoxic states, especially in immobilized patients. Hemoconcen-tration appears to be an important factor in the hypercalcemia associated with adrenal insufficiency and pheochromocytoma, although the latter patients may have associated parathyroid tumors (MEN2A), and some pheochromocytomas are known to secrete PTHrP. Other endocrine lesions such as vasoactive intestinal peptide–secreting tumors


Surgery_Schwartz

Surgery_Schwartz. latter patients may have associated parathyroid tumors (MEN2A), and some pheochromocytomas are known to secrete PTHrP. Other endocrine lesions such as vasoactive intestinal peptide–secreting tumors may be associated with hypercalcemia due to increased secretion of PTHrP. Milk-alkali syndrome requires the ingestion of large quantities of calcium with an absorbable alkali such as that used in the treatment of peptic ulcer disease with antacids. Ingestions of large quantities of vitamins D and A are infrequent causes of hypercalcemia, as is immobilization.Diagnostic Investigations Biochemical Studies. The presence of an elevated serum cal-cium and intact PTH or two-site PTH levels, without hypocal-ciuria, establishes the diagnosis of PHPT with virtual certainty. These sensitive PTH assays use immunoradiometric or immu-nochemiluminescent techniques and can reliably distinguish PHPT from other causes of hypercalcemia. Furthermore, they do not cross-react with PTHrP (Fig. 38-30). In


Surgery_Schwartz

Surgery_Schwartz. use immunoradiometric or immu-nochemiluminescent techniques and can reliably distinguish PHPT from other causes of hypercalcemia. Furthermore, they do not cross-react with PTHrP (Fig. 38-30). In patients with Table 38-10Biochemical features of primary hyperparathyroidismSERUM TESTSALTERATIONCalciumIncreased, except in normocalcemic primary hyperparathyroidismIntact PTHIncreased or inappropriately highChlorideIncreased or high normalPhosphateDecreased or low normalChloride-to-phosphate ratioIncreased (usually >33)MagnesiumUnchanged or decreased (in patients with osteitis fibrosa cystica)Uric acidNormal or increasedAlkaline phosphataseNormal or increased (in the presence of high turnover bone disease)Acid-base statusMild hyperchloremic metabolic acidosisCalcium-to-creatinine clearance ratioGenerally >0.02 (vs. <0.01 in FHH) but there are exceptions1,25-dihydroxy vitamin DNormal or increasedUrine tests 24-h urinary calciumNormal or increasedBFHH = benign familial hypocalciuric


Surgery_Schwartz

Surgery_Schwartz. ratioGenerally >0.02 (vs. <0.01 in FHH) but there are exceptions1,25-dihydroxy vitamin DNormal or increasedUrine tests 24-h urinary calciumNormal or increasedBFHH = benign familial hypocalciuric hypercalcemia; PTH = parathyroid hormone.metastatic cancer and hypercalcemia, intact PTH levels help to determine whether the patient also has concurrent PHPT. Although extremely rare, a patient with hypercalcemia may have a tumor that secretes PTH. FNAB of such a tumor for PTH levels or selective venous catheterization of the veins draining such tumors can help clarify the diagnosis.Patients with PHPT also typically have decreased serum phosphate (∼50%) and elevated 24-hour urinary calcium con-centrations (∼60%). A mild hyperchloremic metabolic acidosis also is present (80%), thereby leading to an elevated chloride-to-phosphate ratio (>33). Urinary calcium levels need not be measured routinely, except in patients who have not had previ-ously documented normocalcemia or have a family history


Surgery_Schwartz

Surgery_Schwartz. an elevated chloride-to-phosphate ratio (>33). Urinary calcium levels need not be measured routinely, except in patients who have not had previ-ously documented normocalcemia or have a family history of hypercalcemia to rule out FHH. In patients with FHH, 24-hour urinary calcium excretion is characteristically low (<100 mg/d). Furthermore, the serum calcium-to-creatinine clearance ratio (24-hour urine calcium/plasma total calcium/24-hour urine creatinine/plasma creatinine) usually is <0.01 in patients with FHH, whereas it is typically >0.02 in patients with PHPT, although there are exceptions to this. Other biochemical features of PHPT are listed in Table 38-10. Elevated levels of alkaline phosphatase may be found in approximately 10% of patients with PHPT and are indicative of high-turnover bone disease. These patients are prone to developing postoperative hypocal-cemia due to bone hunger. Serum and urine protein electropho-resis may be necessary to exclude multiple


Surgery_Schwartz

Surgery_Schwartz. of high-turnover bone disease. These patients are prone to developing postoperative hypocal-cemia due to bone hunger. Serum and urine protein electropho-resis may be necessary to exclude multiple myeloma.Brunicardi_Ch38_p1625-p1704.indd 166901/03/19 11:21 AM 1670SPECIFIC CONSIDERATIONSPART IIOccasionally, patients present with normocalcemic PHPT due to vitamin D deficiency, a low serum albumin, excessive hydration, a high-phosphate diet, or a low normal blood calcium set point. These patients have increased total PTH levels with or without increased blood ionized calcium levels and must be distinguished from patients with renal leak hypercalciuria who also have increased PTH levels due to excessive calcium loss in the urine. This can be accomplished by administering thiazide diuretics. In patients with idiopathic hypercalciuria, the urinary calcium level falls, and the secondary increase in the blood PTH level also decreases to normal, whereas patients with normocal-cemic HPT


Surgery_Schwartz

Surgery_Schwartz. In patients with idiopathic hypercalciuria, the urinary calcium level falls, and the secondary increase in the blood PTH level also decreases to normal, whereas patients with normocal-cemic HPT continue to have elevated urine calcium and blood PTH levels and may, in fact, become hypercalcemic.Radiologic Tests. In patients with profound hypercalcemia or PHPT associated with vitamin D deficiency, hand and skull X-rays may demonstrate osteitis fibrosa cystica, but this is rare in current clinical practice. BMD studies using dual-energy absorptiometry are being increasingly used to assess the effects of PHPT on bone. PHPT primarily leads to one loss at cortical sites such as the distal radius while bone density is preserved at sites such as the lumbar spine. Current evaluation of patients with PHPT includes vertebral imaging by X-ray or vertebral fracture assessment (VFA) or CT scan in addition to BMD stud-ies. Measurement of trabecular bone score (TBS) is optional. In addition, renal


Surgery_Schwartz

Surgery_Schwartz. with PHPT includes vertebral imaging by X-ray or vertebral fracture assessment (VFA) or CT scan in addition to BMD stud-ies. Measurement of trabecular bone score (TBS) is optional. In addition, renal imaging by ultrasound, X-ray, or CT scan is also recommended. Parathyroid localization studies are not used to confirm the diagnosis of PHPT, but rather to aid in identify-ing the location of the offending gland(s), as discussed later in “Preoperative Localization Tests.”Treatment Indications for Parathyroidectomy and Role of Medical Management. Most authorities agree that patients who have developed complications and have “classic” symptoms of PHPT should undergo parathyroidectomy. However, the treatment of patients with asymptomatic PHPT has been the subject of con-troversy, due, in part, to the fact that there is little agreement on what constitutes an asymptomatic patient.At the National Institutes of Health consensus conference in 1990, “asymptomatic” PHPT was defined as “the


Surgery_Schwartz

Surgery_Schwartz. part, to the fact that there is little agreement on what constitutes an asymptomatic patient.At the National Institutes of Health consensus conference in 1990, “asymptomatic” PHPT was defined as “the absence of common symptoms and signs of PHPT, including no bone, renal, gastrointestinal, or neuromuscular disorders.” To deter-mine the best course of action for these patients, it is important to consider the natural history of untreated PHPT and the out-comes of treatment options, both medical and surgical.With respect to the natural history, the panel advocated nonoperative management of these patients with mild PHPT based on observational studies, which suggested relative stabil-ity of biochemical parameters over time. However, the consen-sus panel considered certain patients to be candidates for surgery based on testing or other information indicating end-organ effects or a higher likelihood of disease progression, and this led to the establishment of initial guidelines for


Surgery_Schwartz

Surgery_Schwartz. be candidates for surgery based on testing or other information indicating end-organ effects or a higher likelihood of disease progression, and this led to the establishment of initial guidelines for parathyroidectomy.74 Subsequently, another observational study on the natural history of treated versus untreated HPT was published by Silverberg and colleagues.75 In their cohort of 52 patients with asymptomatic HPT followed without surgery, levels of serum and urinary calcium, PTH, alkaline phosphatase, and vitamin D metabolites remained relatively stable over a 10-year period in most patients. Average bone mass also remained relatively stable. However, the study also reported development of a new indication for surgery in 14 (27%) of 52 of their asymptom-atic patients and, because approximately 50% of their patients were initially treated surgically, overall, about 75% of patients were underwent parathyroidectomy. Age <50 years was predic-tive of progression, and patients undergoing


Surgery_Schwartz

Surgery_Schwartz. 50% of their patients were initially treated surgically, overall, about 75% of patients were underwent parathyroidectomy. Age <50 years was predic-tive of progression, and patients undergoing parathyroidectomy showed not only normalization of calcium and PTH levels but also improved BMD at the spine and hip. Based on these and other studies, the guidelines were reassessed at a second work-shop on asymptomatic PHPT held at the National Institutes of Health in 2002.76Since that time, additional studies have provided further insights into the natural history of treated and untreated HPT. Three of these were randomized, controlled, prospective studies ranging in duration from 1 to 3.5 years. One was an observa-tional study (a continuation of the Columbia University PHPT Project) but was notable for its long duration of follow-up of 15 years.77 These studies confirmed the relative stability of vari-ous biochemical indices, thus validating the need for guidelines. However, the long-term


Surgery_Schwartz

Surgery_Schwartz. for its long duration of follow-up of 15 years.77 These studies confirmed the relative stability of vari-ous biochemical indices, thus validating the need for guidelines. However, the long-term study suggested that the stability was not indefinite as calcium levels tended to rise in years 13 to 15. In addition, the study also demonstrated that bone density mea-surements remained stable for 8 to 10 years, but cortical bone density worsened after year 10. More concerning was the fact that 60% of patients lost >10% of their BMD over the 15-year observation period. Furthermore, whether patients met the 2002 guidelines for surgery did not appear to predict the risk of pro-gressive disease, with 40% of patients undergoing follow-up eventually needing surgery. Although there are no randomized trials, registry data also suggest that fracture risk is increased for PHPT up to 10 years prior to diagnosis and treatment.Medical options for treating PHPT and its complications include


Surgery_Schwartz

Surgery_Schwartz. randomized trials, registry data also suggest that fracture risk is increased for PHPT up to 10 years prior to diagnosis and treatment.Medical options for treating PHPT and its complications include antiresorptive treatments such as bisphosphonates, hor-mone replacement therapy (HRT), and selective estrogen recep-tor modulators such as raloxifene.78 Bisphosphonates and HRT are reasonable options in patients for whom skeletal protection is needed, as evidence from randomized, placebo-controlled trials indicates that these medications are very effective at decreasing bone turnover and increasing BMD in PHPT, with the effects being comparable to patients undergoing parathyroidectomy. Caution needs to be exercised due to the nonskeletal effects of HRT, and hence, bisphosphonates are preferred. There are no clinical studies regarding the effects of raloxifene on BMD in HPT, and none of these agents affects calcium or PTH levels. More recently, calcimimetics (modifiers of the sensitivity of


Surgery_Schwartz

Surgery_Schwartz. There are no clinical studies regarding the effects of raloxifene on BMD in HPT, and none of these agents affects calcium or PTH levels. More recently, calcimimetics (modifiers of the sensitivity of the CASR) have been used in randomized, multicenter controlled trials and have been shown to decrease both serum calcium and PTH levels in both symptomatic and asymptomatic PHPT patients. Unfortunately, bone density failed to improve in medi-cally treated patients. Although this therapy shows promise, long-term outcome data are lacking, and their routine use is not advocated at this time, except in patients who are very poor operative risks or refuse surgery.Successful parathyroidectomy results in resolution of oste-itis fibrosa cystica and decreased formation of renal stones in symptomatic (classic) patients. In addition, it results in improved BMD (6% to 8% in the first year and up to 12% to 15% at 15 years) and fracture risk (by 50% at hip and upper arm and 30% overall) after


Surgery_Schwartz

Surgery_Schwartz. (classic) patients. In addition, it results in improved BMD (6% to 8% in the first year and up to 12% to 15% at 15 years) and fracture risk (by 50% at hip and upper arm and 30% overall) after adjustment for age, sex, and previous frac-tures over a 20-year observation period.75 There are also data to show that it improves a number of the nonspecific manifesta-tions of PHPT such as fatigue, polydipsia, polyuria and nocturia, Brunicardi_Ch38_p1625-p1704.indd 167001/03/19 11:21 AM 1671THYROID, PARATHYROID, AND ADRENALCHAPTER 38Table 38-11Indications for parathyroidectomy in patients with asymptomatic primary HPT (2014 NIH consensus conference guidelines)• Serum calcium >1 mg/dL above the upper limits of normal• GFR <60 mL/min; 24-h urine for calcium >400 mg/d (>10 mmol/d) and increased stone risk by biochemical stone risk analysis; presence of nephrolithiasis or nephrocalcinosis by X-ray, ultrasound, or CT• Substantially decreased bone mineral density at the lumbar spine, total hip,


Surgery_Schwartz

Surgery_Schwartz. risk by biochemical stone risk analysis; presence of nephrolithiasis or nephrocalcinosis by X-ray, ultrasound, or CT• Substantially decreased bone mineral density at the lumbar spine, total hip, femoral neck, or distal radius (>2.5 SD below peak bone mass, T score <−2.5; vertebral fracture by X-ray, CT, MRI, or VFA)• Age <50 y• Long-term medical surveillance not desired or possibleGFR = glomerular filtration rate; HPT = hyperparathyroidism; NIH = National Institutes of Health; SD = standard deviation; VFA = vertebral fracture assessmentbone and joint pain, constipation, nausea, and depression in many patients. This also has been demonstrated using symptom questionnaires and various standardized general quality-of-life assessments such as the SF-36 and a specific parathyroidectomy assessment of symptoms scale.79 The increased death rate in patients with PHPT appears to be revers-ible by successful parathyroidectomy, at least in some studies. Lastly, parathyroidectomy can be


Surgery_Schwartz

Surgery_Schwartz. assessment of symptoms scale.79 The increased death rate in patients with PHPT appears to be revers-ible by successful parathyroidectomy, at least in some studies. Lastly, parathyroidectomy can be accomplished with >95% suc-cess rates with minimal morbidity, even in elderly patients and is the only curative treatment option for PHPT. Previous inves-tigations have also documented that parathyroidectomy is more cost-effective than medical management or follow-up.80Given these findings, it is recommended that parathyroid-ectomy should be offered to virtually all patients except those in whom the operative risks are prohibitive. This is also acknowl-edged by the panel of the latest workshop, which stated that “even though patients may not meet the guidelines for surgi-cal intervention, it is always a reasonable option in those who do not have medical contraindications.” This was first stated in the 2008 guidelines and reiterated in the most recent revi-sion in 2014, which advised


Surgery_Schwartz

Surgery_Schwartz. it is always a reasonable option in those who do not have medical contraindications.” This was first stated in the 2008 guidelines and reiterated in the most recent revi-sion in 2014, which advised parathyroidectomy for patients with smaller elevations in serum calcium levels (>1 mg/dL above the upper limit of normal) and if BMD measured at any of three sites (radius, spine, or hip) is greater than 2.5 standard deviations below those of genderand race-matched, not age-matched, controls (i.e., peak bone density or T score [rather than Z score] <2.5). In addition, patients <50 years of age were advised to undergo parathyroidectomy. Parathyroidectomy is also indicated for creatinine clearance <60 cc/minute and urine calcium >400 mg/day in the presence of increased stone risk by biochemical stone risk analysis. The significant changes from the previous guidelines pertain to the fact that (a) patients with nephrolithiasis or nephrocalcinosis by X-ray, ultrasound, or CT scan and (b) those


Surgery_Schwartz

Surgery_Schwartz. stone risk analysis. The significant changes from the previous guidelines pertain to the fact that (a) patients with nephrolithiasis or nephrocalcinosis by X-ray, ultrasound, or CT scan and (b) those with vertebral fracture by X-ray, CT, MRI, or VFA are also candidates for parathyroidectomy.81,82 The current guidelines are summarized in Table 38-11.It is important to point out that the neurocognitive and neuropsychological aspects of PHPT remain a topic of con-troversy with respect to the guidelines for parathyroidectomy. Although there were more studies since the previous iteration 6of the guidelines, there were concerns that while some lacked adequate controls and were plagued by problems related to the instruments used to quantify these nonspecific symptoms, others showed variability in improvement of neurocognitive symptoms following parathyroidectomy. Similarly, uncertainty is also present concerning the cardiovascular consequences of mild HPT. Therefore, the workshop panel


Surgery_Schwartz

Surgery_Schwartz. in improvement of neurocognitive symptoms following parathyroidectomy. Similarly, uncertainty is also present concerning the cardiovascular consequences of mild HPT. Therefore, the workshop panel emphasizes that these criteria alone should not be used as guidelines for surgical intervention.Since there are no definitive criteria to indicate which patients with mild PHPT will develop progressive disease, more clinical studies are required. Patients who do not undergo sur-gery should undergo routine follow-up as outlined in the recent workshop summary statement, consisting of annual calcium and serum creatinine measurements, and measurements of BMD at three sites every 1 to 2 years.82Preoperative Localization Tests. Localization studies may be classified into noninvasive or invasive modalities. These stud-ies have variable performance characteristics, which, in turn, vary with operator and institutional experience, as outlined in Table 38-12. Localization studies have permitted


Surgery_Schwartz

Surgery_Schwartz. modalities. These stud-ies have variable performance characteristics, which, in turn, vary with operator and institutional experience, as outlined in Table 38-12. Localization studies have permitted surgeons to perform more limited operations, some of them under local anesthesia. These “minimally invasive” procedures include uni-lateral and focused neck exploration, radio-guided parathyroid-ectomy, and several endoscopic or video-assisted approaches. The use of localization studies has been shown in some studies to be associated with lower morbidity rates (hypoparathyroidism and RLN injury) and decreased operative times, reduced dura-tion of hospital stay, and improved cosmetic outcomes, while maintaining success rates similar to those obtained with tradi-tional bilateral neck explorations. Some studies also show that use of localization studies may be more cost-effective. Overall, it has become routine to localize hyperfunctioning parathyroid glands before parathyroidectomy. It is


Surgery_Schwartz

Surgery_Schwartz. Some studies also show that use of localization studies may be more cost-effective. Overall, it has become routine to localize hyperfunctioning parathyroid glands before parathyroidectomy. It is important to point out that imaging is not a diagnostic approach, and the decision for exploration should be made before any imaging is performed.99mTc-labeled sestamibi (Fig. 38-31A) is the most widely used and accurate modality with a sensitivity >80% for detec-tion of parathyroid adenomas. Sestamibi (Cardiolite) initially was introduced for cardiac imaging and is concentrated in mitochondria-rich tissue. It was subsequently noted to be useful for parathyroid localization due to the delayed washout of the radionuclide from hypercellular parathyroid tissue compared to thyroid tissue. Sestamibi scans generally are complemented by neck ultrasound (Fig. 38-31B), which can identify adenomas with >75% sensitivity in experienced centers and is most useful in identifying intrathyroidal parathyroids.


Surgery_Schwartz

Surgery_Schwartz. generally are complemented by neck ultrasound (Fig. 38-31B), which can identify adenomas with >75% sensitivity in experienced centers and is most useful in identifying intrathyroidal parathyroids. Single-photon emis-sion CT, particularly when used with CT, has been shown to be superior to other nuclear medicine–based imaging. Specifically, single-photon emission CT can indicate whether an adenoma is located in the anterior or posterior mediastinum (aortopulmo-nary window), thus enabling the surgeon to modify the opera-tive approach accordingly. CT and MRI scans are less sensitive than sestamibi scans, but they are helpful in localizing large paraesophageal and mediastinal glands. More recently, four-dimensional CT (4D-CT) has shown utility in parathyroid local-ization. This technique incorporates the perfusion of contrast in hyperfunctioning parathyroid tissue over time, thus providing functional information in addition to the anatomic information provided by conventional


Surgery_Schwartz

Surgery_Schwartz. incorporates the perfusion of contrast in hyperfunctioning parathyroid tissue over time, thus providing functional information in addition to the anatomic information provided by conventional three-dimensional CT imaging. In one study, 4D-CT showed improved sensitivity of 88% compared to Brunicardi_Ch38_p1625-p1704.indd 167101/03/19 11:21 AM 1672SPECIFIC CONSIDERATIONSPART IIthat of sestamibi (65%) and ultrasound (57%) for lateralization of the enlarged gland and also showed superiority when local-ization to the correct quadrant was examined.83 A combination of 4D-CT and ultrasound has been reported to have a positive predictive value of 92% for single-gland disease and 75% for multiple-gland disease.IOPTH was initially introduced in 1993 and is used to determine the adequacy of parathyroid resection (Fig. 38-32).84 According to one commonly used criterion, when the PTH falls by 50% or greater 10 minutes after removal of a parathyroid tumor, as compared to the highest preremoval


Surgery_Schwartz

Surgery_Schwartz. resection (Fig. 38-32).84 According to one commonly used criterion, when the PTH falls by 50% or greater 10 minutes after removal of a parathyroid tumor, as compared to the highest preremoval value, the test is considered positive, and the operation is terminated. IOPTH measurements, like localization studies, are less reliable in mul-tiglandular disease. Bilateral internal jugular vein sampling has also been used to lateralize tumors intraoperatively but is less accurate.Operative Approaches Unilateral parathyroid exploration was first carried out using intraoperative staining of a biopsy from the normal parathyroid gland with Sudan black dye to rule out a double adenoma. Initially, the choice of side to be explored was random, but the introduction of preoperative localization studies has enabled a more directed approach. In contrast, the focused approach identifies only the enlarged parathyroid gland, and no attempts are made to locate other parathyroid glands. Unilateral neck


Surgery_Schwartz

Surgery_Schwartz. has enabled a more directed approach. In contrast, the focused approach identifies only the enlarged parathyroid gland, and no attempts are made to locate other parathyroid glands. Unilateral neck explorations have several advantages over bilateral neck exploration, including reduced operative times and complications, such as injury to the RLN and hypoparathyroidism. However, Table 38-12Commonly used parathyroid localization studiesSTUDYADVANTAGESDISADVANTAGESPreoperative, noninvasive Sestamibi-technetium-99m scanAllows planar and SPECT imagingFalse-positive tests due to thyroid neoplasms, lymphadenopathyUltrasoundIdentification of juxtaand intrathyroidal tumorsFalse-positive results due to thyroid nodules, cysts, lymph nodes, esophageal lesions Relatively inexpensiveFalse-negatives result from substernal, ectopic, and undescended tumorsCT scanLocalization of ectopic (mediastinal) glandsNot useful for juxtaor intrathyroidal glands False-positive results from lymph nodes Relatively


Surgery_Schwartz

Surgery_Schwartz. from substernal, ectopic, and undescended tumorsCT scanLocalization of ectopic (mediastinal) glandsNot useful for juxtaor intrathyroidal glands False-positive results from lymph nodes Relatively high cost Radiation exposure Requires IV contrast Interference from shoulders and metallic clipsMRI scanLocalization of ectopic tumorsExpensive No radiation exposureFalse-positive results from lymph nodes and thyroid nodules No IV contrastCannot be used in claustrophobic patientsFour-dimensional CT scanStructural and functional informationSimilar to CT scanPreoperative, invasiveFNABCan distinguish parathyroid tumor from lymphadenopathy using PTH assayExperienced cytologist neededAngiogramProvides a road map for selective venous samplingExpensive Treatment of mediastinal tumors by embolizationExperienced radiologist needed Neurologic complicationsVenous samplingUseful to lateralize tumor in equivocal cases or negative localization studiesExpensive, experienced radiologist


Surgery_Schwartz

Surgery_Schwartz. by embolizationExperienced radiologist needed Neurologic complicationsVenous samplingUseful to lateralize tumor in equivocal cases or negative localization studiesExpensive, experienced radiologist neededIntraoperativePTH assayImmediate confirmation of tumor removalExpensive Increased operative time, decreased accuracy in multiple-gland diseaseCT = computed tomography; FNAB = fine-needle aspiration biopsy; IV = intravenous; MRI = magnetic resonance imaging; PTH = parathyroid hormone; SPECT = single-photon emission computed tomography.Brunicardi_Ch38_p1625-p1704.indd 167201/03/19 11:21 AM 1673THYROID, PARATHYROID, AND ADRENALCHAPTER 38ABFigure 38-31. A. Sestamibi scan in a patient with primary hyperparathyroidism showing persistent uptake suggesting a left lower hypercel-lular parathyroid gland. B. Neck ultrasound in a patient with primary hyperparathyroidism showing a left lower parathyroid adenoma.most existing studies comparing the two approaches are retro-spective and do not


Surgery_Schwartz

Surgery_Schwartz. gland. B. Neck ultrasound in a patient with primary hyperparathyroidism showing a left lower parathyroid adenoma.most existing studies comparing the two approaches are retro-spective and do not analyze the results on an intent-to-treat basis. Another argument against a unilateral exploration is the risk of missing another adenoma on the opposite side of the neck. The incidence of double adenomas has been reported to range from 0% to 10%, with an increased incidence in elderly patients. The risk of missing a second adenoma is higher in populations with a higher incidence of multiple adenomas, such as those with famil-ial HPT, MEN syndromes, and the elderly. Another difficulty inherent with unilateral exploration is the inability to discern whether the combination of an abnormal gland and a normal gland on the initial side constitutes a single adenoma or asym-metric hyperplasia. A recently published update on the 5-year results of a randomized trial comparing unilateral versus bilateral


Surgery_Schwartz

Surgery_Schwartz. normal gland on the initial side constitutes a single adenoma or asym-metric hyperplasia. A recently published update on the 5-year results of a randomized trial comparing unilateral versus bilateral neck exploration did not note any difference in the rates of recur-rent or persistent disease in the two groups of patients.85 These issues will only be resolved by a large, prospective, multicenter study or improved molecular analytic techniques.Brunicardi_Ch38_p1625-p1704.indd 167301/03/19 11:21 AM 1674SPECIFIC CONSIDERATIONSPART IIRadio-guided parathyroidectomy takes advantage of the ability of parathyroid tumors to retain 99mTc-sestamibi. Before sur-gery, 1 to 2 mCi of the isotope is injected, and a hand-held gamma probe is used to guide the identification of the enlarged gland, taking care to ensure the equilibration of radioactivity counts in all quadrants. Reported advantages include easier localization, par-ticularly in reoperative cases, and the ability to perform the


Surgery_Schwartz

Surgery_Schwartz. taking care to ensure the equilibration of radioactivity counts in all quadrants. Reported advantages include easier localization, par-ticularly in reoperative cases, and the ability to perform the pro-cedure under local anesthetic or sedation using smaller incisions. Many studies demonstrated the feasibility of this technique; how-ever, it is rarely used now, largely because it offers little advantage over preoperative sestamibi scans and is associated with increased operative times. Like preoperative scanning, it also has reduced accuracy in the presence of multiglandular disease.Endoscopic approaches include both video-assisted and total endoscopic techniques. Total endoscopic parathyroidec-tomy was first described by Gagner in 1996,86 and several other investigators have since reported on this technique. Although port placements are variable, as is the case with endoscopic thy-roidectomy, they all involve creation of a working space in the neck using CO2 insufflation, with the