A person with hyperparathyroidism may have severe symptoms, subtle ones, or none at all. More than 99 percent of the time, the parathyroid glands exhibit a benign enlargement, usually of only one gland, but sometimes more than one will be involved. Increasingly, routine blood tests that screen for a wide range of conditions, including high calcium levels, are alerting doctors to people who have mild forms of the disorder even though they are symptom-free.
When symptoms do appear, they are often mild and nonspecific, such as a feeling of weakness and fatigue, depression, or aches and pains. With more severe disease, a person may have a loss of appetite, nausea, vomiting, constipation, confusion or impaired thinking and memory, and increased thirst and urination. Patients may have thinning of the bones without symptoms, but with risk of fractures. Increased calcium and phosphorus excretion in the urine may cause kidney stones.
In most cases doctors don't know the cause of the condition. The vast majority of cases occur in people with no family history of the disorder. Only about five percent of cases can be linked to an inherited problem. Familial multiple endocrine neoplasia type 1 is a rare, inherited syndrome that affect the parathyroids, as well as the pancreas and the pituitary gland. Another rare genetic disorder, familial hypocalciuric hypercalcemia, is sometimes confused with typical hyperparathyroidism. Each accounts for about 2 percent of primary hyperparathyroidism cases. A childhood history of radiation treatments for acne or other condition in the head and neck area (common in the 1940s to 1950s) can also increase the risk of hyperparathyroidism.