Hyperparathyroidism is an increase in parathyroid hormone (PTH) levels in the blood. This occurs from a disorder either within the parathyroid glands (primary hyperparathyroidism) or outside the parathyroid glands (secondary hyperparathyroidism). Most people with primary disease have no symptoms at the time of diagnosis. When symptoms occur, they are due to elevated blood calcium. With long-standing elevation, the most common symptom is kidney stones. Other symptoms may include bone pain, weakness, depression, confusion, and increased urination. Both primary and secondary may result in osteoporosis (weakening of the bones).In 80% of cases, primary hyperparathyroidism is due to a single benign tumor known as a parathyroid adenoma. Most of the remainder are due to several of these adenomas. Rarely it may be due to parathyroid cancer. Secondary hyperparathyroidism typically occurs due to vitamin D deficiency, chronic kidney disease, or other causes of low blood calcium. The diagnosis of primary hyperparathyroidism is made by finding elevated calcium and PTH in the blood.Primary hyperparathyroidism may be cured by removing the adenoma or overactive parathyroid glands. In those without symptoms, mildly increased blood calcium levels, normal kidneys, and normal bone density monitoring may be all that is required. The medication cinacalcet may also be used to decrease PTH levels. In those with very high blood calcium levels, treatment may include large amounts of intravenous normal saline. Low vitamin D levels should be corrected.Primary hyperparathyroidism is the most common type. In the developed world, between one and four per thousand people are affected. It occurs three times more often in women than men and is typically diagnosed between the ages of 50 and 60. The disease was first described in the 1700s. In the late 1800s, it was determined to be related to the parathyroid. Surgery as a treatment was first carried out in 1925.