CALCIUM AND STRONTIUM METABOLIC STUDIES IN PATIENTS ON CAPD

Background: Strontium is known to affect calcium metabolism both exper imentally and in clinical studies on conditions other than end-stage r enal failure (ESRF) and continuous ambulatory peritoneal dialysis (CAP D). Objective:To investigate Sr metabolism in relation to that of Ca i n ESRF patients undergoing CAPD, and the possible influence of the dur ation of treatment. Design: Cross-sectional observational study. Setti ng: University medical center and Institute of Nuclear Physics. Patien ts: Twenty-four patients on CAPD; 14 chronic renal failure (CRF) patie nts not on dialysis, and 52 healthy controls. Measurements: Calcium an d Sr content of serum, urine or dialysate effluent, and selected dieta ry products. Results: Calcium and Sr are absorbed by the intestinal tr act of healthy subjects with equal efficiency. Serum Ca levels were co nsiderably lower in CRF patients than in healthy subjects and patients on CAPD (p < 0.001). Serum Sr was significantly higher in both CAPD a nd CRF patients than in healthy controls (p < 0.001). The Sr/Ca ratio in the sera of the healthy subjects was defined by the preferential ex cretion of Sr over Ca by the kidney. This preferential excretion was l ost during renal failure. During treatment there was a tendency for th e uptake of both Ca and Sr to increase. Conclusions: Strontium is accu mulated in the body during renal failure and CAPD cannot restore norma l levels. Considering the varying effects of different doses of Sr on bone metabolism experimentally, it would be interesting to determine b y further studies the possible significance of the observed Sr accumul ation for renal bone disease.