Abstract
This thesis will describe the regulation of serum phosphorus at a time when the body is using bone calcium to maintain the level of the serum calcium. Such a state was induced by severe restriction in the dietary calcium intake. The general response of the body in respect to conservation and loss of both calcium and phosphate and the maintenance of the serum calcium will be discussed only as supplementary material. | It is known that the serum calcium is normally maintained between 9 and 11 mgm per 100 cc of serum (1). This total serum calcium represents contributions from calcium absorbed in the gut, calcium reabsorbed in the renal tubules, and calcium released from bone. | The calcium absorbed from the gut represents both the absorption of ingested calcium as well as calcium reabsorbed from the secreted intestinal juices (1). The intestinal absorption of calcium is dependent on two factors, parathyroid hormone and Vitamin D. | While the absorption of calcium is decreased in states of reduced parathyroid function, the exact mechanism responsible for the facilitation of calcium absorption by parathyroid hormone is undefined (2). It appears that Vitamin D must be present for parathyroid hormone to show this ability to increased calcium absorption.