A condition resulting from excess production of parathyroid hormone (hyperparathyroidism). Hyperparathyroidism is characterized by elevation of calcium in the blood. It may cause thinning of the bones and kidney stones . If hyperparathyroidism is severe, osteitis fibrosa cystica can occur. Then, normal bone may become softened, deformed and develop cysts (lumps).
Causes, incidence, and risk factors
There are 4 parathyroid glands in the neck. They produce parathyroid hormone, which helps control calcium levels in the body. Sometimes they 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 it, and it sometimes runs in families. Neck radiation increases the likelihood of developing this disorder. Parathyroid hormone increases bone "turnover" (metabolism) and may soften it. Before 1950, about half of people diagnosed with hyperparathyroidism had osteitis fibrosa cystica. Now it is uncommon (less than 10% of people with hyperparathyroidism) because patients 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 cystica.
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 abnormal parathyroid gland(s). New techniques include using radioactive tracers and rapid parathyroid hormone blood tests during surgery to make it quicker and easier. If surgery is not possible, drugs can sometimes be used to lower calcium levels.
Expectations (prognosis)
All the bone problems of osteitis fibrosa cystica are reversible with surgery, except for the fluid-filled cysts.
Complications
Complications of osteitis fibrosa cystica include bone fractures, pain and deformities. There may be other problems stemming from the hyperparathyroidism itself such as kidney stones and failure.
Calling your health care provider
A physician should be called if you notice bone pain, tenderness, or if you have a fracture or any of the symptoms of hyperparathyroidism.
Prevention
Today, most people have blood tests from time to time. Therefore, high calcium levels are usually found before any severe damage is done. A bone density test (X-ray measure of bone strength) can be done. People with hyperparathyroidism are more likely to have just osteopenia (thin bones) or osteoporosis (very thin bones) than to have full-blown osteitis fibrosa cystica. Most patients with hyperparathyroidism have no symptoms, and many can be followed with blood tests and bone measurements. Others are advised to have surgery, to prevent further problems.