© 1986 American Society for Clinical Nutrition

The effect of phosphorus on endogenous fecal calcium excretion in man”2 Herta Spencer, MD, Lois Kramer, RD. Nunilo Rubio, MD, and Dace Osis ABSTRACT The effect ofphosphorus on the endogenous fecal calcium excretion was investigated in man by administering tracer doses of47Ca intravenously in control studies and during phosphorus supplementation. The phosphorus intake was 800 mg/day in control studies and 2000 mg during phosphorus supplementation ofthe constant diet. The studies were carried out during different calcium intake levels of 200, 800, 1300, 2000, and 2600 mg/day. Following the dose of47CaCl2, the values ofthe plasma levels, urinary, and fecal excretions of47Ca were used to calculate the endogenous fecal calcium. None ofthese values differed significantly during phosphorus supplementation from those in corresponding control studies, irrespective ofthe calcium intake. During addition of phosphorus to the different calcium intakes, a consistent finding was a significant decrease ofthe urinary calcium and a slight, but not significant increase ofthe fecal calcium except during the 800 mg calcium intake