Abstract
Thyrocalcitonin is a recently discovered thyroid polypeptide which inhibits the efflux of skeletal calcium and thereby can rapidly lower blood calcium. The discovery and known properties of thyrocalcitonin are reviewed. It is postulated that its physiological function is to prevent even transient hypercalciuria and the threat of calculus formation. It can bring about rapid control of incipient hypercalcemia, avoiding an increased glomerular filtration of calcium, and at the same time permit the continued effect of long-acting parathyroid hormone on the renal tubule which achieves the removal of nearly 99% of the filtered calcium from the urine. The therapeutic use of thyrocalcitonin in patients threatened by hypercalcemia or hypercalciuria is anticipated.