Vitamin B-6 status of children undergoing continous ambulatory peritoneal dialysis

The purpose of this study was to evaluate the vitamin B-6 status of children undergoing continuous ambulatory peritoneal dialysis (CAPD) and to determine the renal and peritoneal clearance of vitamin B-6 in these children. Eight children, mean age 12 years, were included in the first study. Urine, dialysate and plasma were analyzed for total vitamin B-6 and pyridoxal 5′-phosphate (PLP). Dialysate total protein and serum alkaline phosphatase were also measured and a three day dietary record was obtained. Plasma PLP was measured in six subjects one year following the first study after they had been receiving daily pyridoxine supplements for one year. Mean plasma total vitamin B-6 and PLP were 304 and 25.5 nM, respectively, in the first study. The mean ratio of plasma PLP/total vitamin B-6 was 0.146. Mean plasma PLP in supplemented subjects was 60.4nM. Renal and dialysate clearance of vitamin B-6 was 0.41 and 0.90 mls/min, respectively. Mean dietary intake of vitamin B-6 was 59% of the RDA. CAPD treated children appear to be deficient in vitamin B-6 although dialysate losses are minimal. Pyridoxine supplements of at least 2mg/day are necessary to increase plasma PLP to normal concentrations in these children.