Primary hyperparathyroidism is the most common form of hyperparathyroidism, and typically affects otherwise healthy individuals. Approximately 90 percent of patients with hyperparathyroidism have primary hyperparathyroidism. This disease is caused by a benign growth and overproduction of parathyroid hormone by one of the four parathyroid glands.
In around 10 to 20 percent of patients, there is more than one gland that produces too much parathyroid hormone. These glands begin to grow and produce too much hormone because the patient has a genetic mutation or defect in the cells, which produce parathyroid hormone and regulate the level of calcium in the blood.
The risk of parathyroid cancer is rare, and most patients with primary hyperparathyroidism can be treated successfully with a single surgery.