Intestinal Phosphate Absorption in Normal and Uremic Man: Effects of 1,25(OH)2-Vitamin D3 and 1α(OH)-Vitamin D3
The action of vitamin D on the intestinal absorption of phosphorus has not been studied extensively in man. Limitations in the use of 32P labeled phosphate have restricted observations in large part to those of net absorption derived from metabolic balance techniques. Using such methods, Stanbury and Lumb (1) and Stanbury (2) reported that pharmacologic doses of vitamin D promoted equimolar increments in the net absorption of calcium and phosphorus in patients with advanced renal failure and severe bone disease. Such a relationship between the absorption of calcium and that of phosphorus supports the viewpoint that phosphate transport across the intestine is dependent upon that of calcium. Recent studies in the rat and chick indicate that vitamin D or its active forms stimulates intestinal transport of phosphorus independent of an effect on calcium (3, 4). In the present study, we have evaluated the effect of treatment with 1,25-dihydroxy-vitamin D3 (1,25 (OH)2D3) or 1α-hydroxy-vitamin D3 (1α(OH)D3) on net absorption of phosphorus in patients with advanced renal failure and normal volunteers. The results in man indicate that both analogs of vitamin D enhance the intestinal net absorption of phosphorus.
KeywordsPhosphate Transport Uremic Patient Intestinal Transport Advanced Renal Failure Label Phosphate
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