INTERACTION OF PARATHYROID HORMONE AND VITAMIN D ON THE RENAL EXCRETION OF PHOSPHATE*

Abstract

THE interrelationships of parathyroid hormone and vitamin D are important for the understanding of the pathogenesis and treatment of rickets and also to explain the apparently paradoxical action of vitamin D in hypoparathyroidism. This study attempts to explain their interaction on the kidney. Vitamin D has been shown under certain conditions to increase tubular reabsorption of phosphate, and parathyroid hormone has been shown to decrease this reabsorption (1, 2). On the other hand patients with hypoparathyroidism may be treated with large doses of vitamin D with a resultant increased urinary excretion of phosphate and reduction of the concentration of phosphorus in the serum. More recently it has been demonstrated that parathyroid extract given intravenously increases the glomerular filtration rate and renal blood flow. (3) Crawford has recently suggested that elevation of serum phosphate stimulates parathyroid secretion (4).