Calcitonin A hormone produced and secreted by the parafollicular cells of the thyroid gland. An action of calcitonin is to inhibit bone reabsorption, inhibit calcium absorption in the gastrointestinal tract, increase calcium and phosphate excretion from the kidneys. Serum Plasma Serum Adult Male: < 40 pg/ml Female: < 25 pg/ml Infant Cord blood: 30-240 pg/ml 7 days old: 77-293 pg/ml Plasma Male: 19 pg/ml Female: 14 pg/ml To diagnose medullary carcinoma of the thyroid gland Carcinoma of the thyroid Chronic renal failure Ectopic secretion by malignant tumors Endocrine tumors of the pancreas Pernicious anemia Subacute Hashimoto's Thyroiditis Parathyroid adenoma or hyperplasia Pregnancy Noncompliance with fasting requirement