THE PRESENT state of our knowledge concerning the physiology of the parathyroid glands has developed by observing the effects of parathyroidectomy,1,2 noting the responses following parathyroid extract administration,3,4 by studies of the metabolism of calcium and phosphorus, and systematic observations of parathyroid function in the normal and abnormal state. Excessive parathyroid hormone elevates the serum calcium and has a phosphate diuretic influence.4 Recently, Copp et al,5 showed that the extract contains a fraction which lowers previously elevated serum calcium. Whether this originates from thyroid or parathyroid in man has yet to be determined.
Normal Homeostasis of Calcium and Phosphate
It is generally agreed that the main physiologic actions of the parathyroid glands are upon the metabolism of calcium and phosphate, and therefore upon bone, which is the chief reservoir of these two minerals.The parathyroid glands provide one of the chief mechanisms for the maintenance of a constant serum calcium