Calcitonin (Thyrocalcitonin) details

Calcitonin is a hormone produced by specialized C-cells in the thyroid gland that helps regulate calcium levels, though its role in everyday calcium balance is relatively minor compared to parathyroid hormone. Its main clinical use is as a marker for medullary thyroid cancer, a less common type of thyroid cancer that arises from these C-cells — significantly elevated calcitonin is a strong indicator of this specific cancer type, and the test is used both to help diagnose it and to monitor for recurrence after treatment. It's also sometimes checked in people with a family history of medullary thyroid cancer or related genetic syndromes (like MEN2), since these conditions run in families.