Advances in vitamin D metabolism as they pertain to chronic renal disease.

Many clinical similarities between renal osteodystrophy and nutritional rickets have suggested that a defect in either the metabolism or action of vitamin D exists in chronic renal failure. The discovery of the kidney as the organ that manufactures the active metabolite of vitamin D has provided direct evidence for a relationship between renal failure and altered vitamin D metabolism. Other observations suggest that an abnormality of vitamin D action could underlie both osteomalacia and osteitis fibrosa (secondary hyperparathyroidism) observed in patients with chronic renal failure. The administration of the active vitamin D analogs, 25(OH)D3, 1,25(OH)2D3, and lalpha(OH)D3, to uremic patients with symptomatic bone disease is capable of reversing many of the abnormalities of divalent ion metabolism. The widespread availability of these agents in the future may provide the clinician the means to correct or even prevent the serious bone disease that frequently complicates the course of chronic renal failure.