Osteitis fibrosa

Alternative names

Osteitis fibrosa cystica

Definition

Osteitis fibrosa is a complication of hyperparathyroidism (excess parathryroid hormone production) in which bone becomes softened and deformed and may develop cysts.

Causes, incidence, and risk factors

There are four parathyroid glands in the neck. They produce parathyroid hormone, which helps control calcium levels in the body. Parathyroid hormone increases bone "turnover" (metabolism) and may soften it.

Sometimes the parathyroid glands produce too much parathyroid hormone (hyperparathyroidism). In these cases, one gland may develop a growth (80% of cases), or all 4 glands may enlarge (15% of cases). Rarely, parathyroid cancer may cause the condition.

Hyperparathyroidism is most common in women over 60. Genetic changes cause the condition, and it sometimes runs in families. Neck radiation increases the likelihood of developing this disorder.

Before 1950, about half of people diagnosed with hyperparathyroidism had osteitis fibrosa. Now it is uncommon - occurring in fewer than 10% of people with hyperparathyroidism - because patients with hyperparathyroidism are diagnosed earlier and have milder elevations of calcium.

People with severe hyperparathyroidism, or those who have parathyroid cancer, are more at risk for developing osteitis fibrosa.

Symptoms

Osteitis fibrosa cystica may cause bone pain or tenderness. There may be fractures (breaks) in the arms, legs, or spine, or deformities (bowing of the bones). Hyperparathyroidism itself may cause Kidney stones or problems, nausea or Constipation, or fatigue and weakness.

Signs and tests

Blood tests show a high level of calcium and alkaline phosphatase (a bone chemical). Phosphorus may be low. The level of parathyroid hormone is elevated.

X-rays may show thin bones, fractures, bowing, and cysts. The cysts may be filled with clear fluid or filled with material ("brown tumors"). The skull may look like "ground glass" or "salt and pepper." The outer part of bones may be eroded; the most sensitive area to check is the fingers. Teeth X-rays may also be abnormal.

Treatment

The main treatment for hyperparathyroidism is surgery to remove the abnormal parathyroid gland(s).

Newer techniques use radioactive tracers and rapid parathyroid hormone blood tests to make the surgery quicker and easier. If surgery is not possible, drugs can sometimes be used to lower calcium levels.