Hyperparathyroidism is a condition in which there is excessive secretion of parathyroid hormone. The principal target organs are the kidney and bone, with a secondary effect on the gut through 1,25 dihydroxy vitamin D.

Hyperparathyroidism can be primary, secondary or tertiary according to the extent of excessive parathyroid hormone produced, and the degree of autonomy of the parathyroid glands.

Clinically, there may be effects of both hypercalcaemia and of hypocalcaemia.

Investigations should include serum calcium and phosphate, and parathyroid hormone.

Treatment depends on the cause.