Familial isolated hyperparathyroidism is a genetic condition that affects the parathyroid glands. These four small glands sit behind your thyroid in your neck. They make parathyroid hormone, or PTH, which controls calcium levels in your blood and bones.
In this condition, one or more parathyroid glands become enlarged and produce too much PTH. The extra hormone pulls calcium from your bones into your bloodstream. This leads to high blood calcium levels, a problem called hypercalcemia. Unlike other hereditary parathyroid disorders, this condition affects only the parathyroid glands. It does not cause tumors in other hormone-producing organs.
Because this condition runs in families, multiple members across generations may develop it. Early detection through blood testing helps prevent complications like kidney stones, bone weakness, and heart problems. Knowing your family history is key to catching this condition before serious symptoms appear.