Calcitonin is a hormone manufactured by a small group of specialized thyroid cells called “C cells.” Calcitonin plays a very discreet role in calcium and bone metabolism, since neither a deficiency nor an excess of calcitonin has any clinical manifestations. The calcitonin test is used to detect two rare disorders: C cell hyperplasia and medullary thyroid cancer.
A significant increase in calcitonin levels is generally indicative of C cell hyperplasia or medullary thyroid cancer.
This possibility must be confirmed by other means, such as thyroid biopsy, ultrasound or thyroid scan. About one quarter of medullary thyroid cancers are caused by the mutation of a gene (the RET gene) that can be passed on from parent to child. This mutation comes with a variety of disorders (MEN 2/multiple endocrine neoplasia type 2) and can include overactivity of other glands such as the adrenal medulla (pheochromocytoma) or parathyroid glands (primary hyperparathyroidism), and disorders of the tongue and lips (neuromas), intestines (ganglioneuromatosis) or the shape of the skull and skeleton (marfanoid body shape).