2012年8月30日 星期四

Doctor, What Do I Do If I Think I Have Osteoporosis?

Bone is a living tissue that undergoes constant change. This series of changes is called "remodeling." Old bone is removed and new bone is formed.

The structure of bone consists of a matrix composed of a framework of collagen and minerals. While the character of bone is different in different areas of the skeleton, the common thread is that if the collagen framework or the minerals aren't properly remodeled, then bone quality is compromised. This leads to an increased risk for fracture. The typical situation- and the one that is responsible for post-menopausal osteoporosis- is that too much bone tissue is removed and not enough is built. When this abnormal bone is subjected to daily wear and tear, "microcracks" in the bone accumulate leading to fracture.

The first place to start if you suspect you may be at risk for osteoporosis is to find the right kind of doctor. This is usually a rheumatologist who specializes in osteoporosis.

He or she will take a careful history looking for risk factors. Among the most common are: female gender, advancing age, family history, small body frame, Caucasian or Asian race, chronic kidney or bowel disease, cigarette smoking, alcoholism, high caffeine intake, and chronic steroid or blood thinner therapy.

Other medical conditions which may be associated with osteoporosis are diabetes, overactive thyroid disease, lung disease, alcoholism, and hormone (estrogen or testosterone) deficiency.

Ideally, a careful history evaluating a patient's risk for falls should also be taken. Impaired vision and environmental hazards such as poor lighting in the home, etc. should be looked into.

After the history, a careful physical examination looking for specific causes of bone loss such as thyroid disease, vitamin deficiency, or other conditions should be performed.

Then, a full laboratory workup consisting of complete blood count, erythrocyte sedimentation rate (ESR), thyroid blood tests, blood chemistries, urinalysis, serum vitamin D levels, and 24 hour urine tests measuring calcium and phosphorus should be obtained.

If there is evidence of fracture in the spine, x-rays may be obtained. Some people may have what are called insufficiency fractures. These are fractures that develop spontaneously in people with very low bone strength. Often these types of fractures will not show up on regular x-ray. Bone scans and magnetic resonance imaging (MRI) may then be required. Special urine tests for bone markers may also be ordered. These urine tests may yield a clue that bone is undergoing improper remodeling.

A bone density scan (also called a dual-energy x-ray absorptiometry scan or DEXA) is mandatory! These scans should be interpreted by a trained rheumatologist. This scan measures the actual "thickness" of bone. DEXA scans are also an excellent method for evaluating the effectiveness of drug therapy... once the patient has been started on the proper medication.

In some instance, a bone biopsy may be required. This procedure involves the extraction of a plug of bone from the pelvis. This is done using local anesthetic and provides a specific look at bone architecture.

In future articles, treatment of osteoporosis will be discussed.

