Does amino acid-based peritoneal dialysate change homocysteine metabolism in continuous ambulatory peritoneal dialysis patients?

Abstract

◆ Objective: We examined whether amino acid-based peritoneal dialysate that contains 85 mg/dL L-methionine affects homocysteine (Hcy) metabolism. ◆ Design: The study enrolled 17 adult CAPD patients (11 men, 6 women) who had been receiving CAPD for at least 6 months and who had low serum albumin levels (<3.7 g/dL). Diet was not specifically changed. All of the study patients received daily 4-exchange CAPD treatment, and they used Nutrineal (Baxter Healthcare, Deerfield, IL, U.S.A.) as one of their daily exchanges (first or second exchange). Blood samples were collected every 2 weeks, and Hcy was measured. ◆ Results: After use of Nutrineal, serum albumin was unchanged, but blood urea nitrogen (BUN) and total protein were increased. Before the study began, 1 patient had a very high Hcy level (256 μmol/L); his data were excluded from the analysis. In the remaining 16 patients, baseline Hcy was 24.4 ± 7.0 μmol/L. Levels of Hcy progressively increased with the use of Nutrineal: 28.1 ± 6.2 μmol/L in week 2, 28.4 ± 7.1 μmol/L in week 4, 29.1 ± 7.6 μmol/L in week 6, 29.3 ± 9.0 μmol/L in week 8, 27.5±9.7 μmol/L in week 10, and 30.3 ± 8.2 μmol/L in week 12. ◆ Conclusions: Nutrineal might help to replenish daily protein loss, but it also increased formation of Hcy and, therefore, the potential risk of cardiovascular illness. Further studies will be needed to examine the effect of folic acid and vitamin B12 supplementation in the rescue of that Hcy increase, and also a possible correlation with methylenetetrahydrofolate reductase gene polymorphism.