Abnormally increased activity of the parathyroid glands, which may be primary or secondary; primary hyperparathyroidism is associated with neoplasia or hyperplasia; excess of parathyroid hormone leads to alteration in function of bone, renal tubules, and gastrointestinal mucosa.

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 as response to external stimuli (secondary hyperparathyroidism)...