Q: Tests done during an annual check up showed that my blood calcium level was too high. My doctor has told me that the results of further tests indicate that I have hyperparathyroidism and need an operation. I feel perfectly well and am therefore hesitant to undergo surgery. Could you explain the causes and effects of hyperparathyroidism and why surgery is necessary?
A: Hyperparathyroidism, one of many causes of a high blood calcium (hypercalcemia), is usually diagnosed by blood tests demonstrating elevated levels of both calcium and parathyroid hormone in the blood. This hormone is secreted by a small gland (parathyroid gland) in the neck and, under normal circumstances, maintains levels of blood calcium within the proper range. When overproduction of parathyroid hormone (hyperparathyroidism) occurs, more than 80 percent of the time it results from a small non-malignant tumor of the parathyroid gland. Only about 1 percent of the tumors of the parathyroid gland are malignant. Diffuse overgrowth of the cells of the gland is responsible for most of the other cases of hyperparathyroidism.
Parathyroid hormone causes release of calcium from the bones and also has several actions on the kidneys that tend to raise the blood calcium level. Thus, hyperparathyroidism causes hypercalcemia which, in turn, leads to increased thirst and urination, kidney stones, poor kidney function, nausea, vomiting, loss of appetite, constipation, peptic ulcer, weakness, high blood pressure and impaired concentration. With extreme hypercalcemia come lethargy, confusion and coma. In addition, the increased bone turnover can produce bone pain and fractures.