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Hyperparathyroidism

Disorder of parathyroid glands may result in loss of calcium

The parathyroid glands are adjacent to the thyroid gland. The thyroid and parathyroid glands produce distinctly different hormones that have different functions. Primary hyperparathyroidism occurs when one or more of the parathyroid glands are overactive and release too much parathyroid hormone (PTH) into the blood stream. Too much PTH can result in hypocalcemia since this hormone is involved in maintaining calcium homeostatsis in the body. Hypocalcemia can result in loss of calcium from the bones, which contributes to osteopenia/osteoporosis. When hypocalcemia occurs, the kidneys must metabolize and excrete the excess calcium, which may lead to nephrolithiasis. Other problems associated with hypocalcemia include vitamin D deficiency, cardiac disease and hypertension.

Primary hyperparathyroidism occurs most often in people who are between 50-60 years of age. There is greater prevalence of disease in women than in men. Reactive or secondary hyperthyroidism occurs due to problems such as renal failure. In primary hyperparathyroidism, a tumor called an adenoma forms in one or both of the parathyroid glands, stimulating hyperactivity. The condition is often asymptomatic. If symptoms occur, they may include myalgias, drowsiness and bone and/or joint pain. The health care provider should order an ultrasound scan of the thyroid/parathyroid and laboratory work that includes a serum calcium, a 25-OH vitamin D level, a TSH and a PTH level. Since bone loss may be a complication, patients should have a bone densitometry ordered.

Patients who have very high blood calcium levels usually undergo surgery to remove the overactive parathyroid gland(s) (parathyroidectomy). The gland(s) may be located through the use of a sestamibi scan, in which a small amount of injected radioactive dye is absorbed by the overactive gland(s). One benefit of this type of surgery is a reduction of the odds of forming kidney stones. If the patient develops chronic low calcium levels after the surgery, or hypoparathyroidism, he or she must receive treatment for calcium loss for the rest of his or her life.

Medications prescribed for hyperparathyroidism include calcimimetrics to decrease parathyroid gland secretion of PTH. Bisphosphonates or raloxifene (a selective estrogen receptor modulator) may be prescribed to treat osteopenia along with calcium and vitamin D supplementation. Osteoporosis should be treated with oral or injectable bisphosphonates, denosumab or, in advanced cases, Forteo.

Surgery is not always necessary if a patient has only a slightly elevated blood calcium level, normal bone density and no other complications. In this instance the physician will monitor the patient’s condition and opt for surgery only if the patient’s blood calcium levels rise. Monitoring may involve bone density measurements every year or two and serum creatinine measurements to check kidney function.

Source: American Thyroid Association (www.thyroid.org)

By Staff Writers

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