The role of the kidney in vitamin D metabolism.

The kidney should be regarded as an organ of central importance in the regulation of calcium metabolism. Its secretion product, 1 alpha,25(OH)2D3, is regulated by several factors, including the calcium and phosphorus content of the diet, parathyroid hormone and the level of 1 alpha,25(OH)2D3 itself. The main occasions in health where 1 alpha,25(OH)2D3 secretion is enhanced are during growth and reproduction. In these situations the secretion of this new renal hormone is under at least partial control of growth hormone and prolactin.