Stimulation of duodenal and ileal absorption of phosphate in the chick by low-calcium and low-phosphorus diets.

The intestinal absorption of phosphate has been studied in vivo in the chick using ligated segments of duodenum and ileum. Feeding diets low in calcium (0.1%) and/or low in phosphorus (0.25%) caused an increase in the absorption of phosphate from both the duodenum and ileum. These changes are consistent with a putative increase in the renal production and mucosal uptake of 1,25-dihydroxycholecalciferol.