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Image not available.What is the differential diagnosis of edema? How would you frame the differential?



  1. Distribution of total body water

    1. 67% intracellular; 33% extracellular

    1. Extracellular water: 25% intravascular; 75% interstitial

  2. Regulation of fluid distribution between the intravascular and interstitial spaces

    1. There is constant exchange of water and solutes at the arteriolar end of the capillaries


    1. Movement of fluid from the intravascular space to the interstitium occurs through several mechanisms


      1. Interstitial oncotic pressure pulls fluid into the interstitium

      1. Capillary permeability allows fluid to escape into the interstitium

    1. Movement of fluid from the interstitium to the intravascular space occurs when opposite pressures predominate


      1. Interstitial hydrostatic pressure pushes fluid out of the interstitium

    1. In skeletal muscle, the capillary hydrostatic pressure and the intravascular oncotic pressure are the most important.


  3. Edema formation occurs when there is


    1. An increase in capillary permeability (for example, burns, angioedema)

    1. An increase in interstitial oncotic pressure (for example, myxedema)

    1. A decrease in plasma oncotic pressure (for example, hypoalbuminemia)

    1. Lymphatic obstruction


Although it is possible to construct a pathophysiologic framework (Figure 15–1) for the differential diagnosis of edema, it is more useful clinically to combine anatomic, pathophysiologic, and organ/system frameworks:


  1. Generalized edema due to a systemic cause and manifested by bilateral leg edema, with or without presacral edema, ascites, pleural effusion, pulmonary edema, periorbital edema

    1. Cardiovascular

      1. Systolic or diastolic dysfunction, or both

      1. Constrictive pericarditis

      1. Pulmonary hypertension

    1. Hepatic (cirrhosis)

    1. Renal

      1. Advanced renal failure of any cause

      1. Nephrotic syndrome

    1. Anemia

      Image not available.The most common systemic causes of edema are cardiac, renal, and hepatic diseases as well as anemia.

    1. Nutritional deficiency

    1. Medications

      1. Antidepressants: Monoamine oxidase inhibitors

      1. Antihypertensives

        1. Calcium channel blockers, especially dihydropyridines

        1. Direct vasodilators (hydralazine, minoxidil)

        1. β-Blockers

      1. Hormones

        1. Estrogens/progesterones

        1. Testosterone

        1. Corticosteroids

      1. Nonselective nonsteroidal antiinflammatory drugs (NSAIDs) and cyclooxygenase-2 inhibitors

      1. Rosiglitazone, pioglitazone

    1. Refeeding edema

    1. Myxedema

  2. Limb edema due to a venous or lymphatic cause, manifested by unilateral or bilateral edema

    1. Venous disease

      1. Obstruction

        1. Deep venous thrombosis (DVT) (see Chapter 14, Dyspnea for a full discussion of lower extremity DVT)

        1. Lymphadenopathy

        1. Pelvic mass

      1. Insufficiency

    1. Lymphatic obstruction (lymphedema)

      1. Primary (idiopathic, often bilateral)

        1. Congenital

        1. Lymphedema ...

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