Calcitonin

This is debated. European guidelines favor routine calcitonin for thyroid nodules (to catch MTC early). American guidelines consider it optional because MTC is rare (<5% of thyroid cancers) and cost-effectiveness is uncertain. In India, practice varies — many endocrinologists measure calcitonin, particularly in patients with family history, multiple nodules, or suspicious ultrasound features.

Multiple endocrine neoplasia type 2 is an inherited syndrome caused by RET gene mutations, combining MTC with pheochromocytoma and (in MEN-2A) primary hyperparathyroidism. Calcitonin screening in family members of MEN-2 patients, combined with RET genetic testing, allows early detection or even prophylactic thyroidectomy before cancer develops — often in childhood for high-risk mutations.

Yes. Chronic kidney disease (reduced clearance), proton pump inhibitor use (hypergastrinemia stimulates calcitonin), smoking, hypercalcemia, autoimmune thyroiditis, and pregnancy all cause mild elevations. The pentagastrin or calcium stimulation test and imaging of the thyroid help distinguish benign from malignant causes when basal calcitonin is in the gray zone.