Acid-base balance and nutrition in peritoneal dialysis

Acidosis has been implicated in increased protein catabolism and malnutrition of dialysis. The present study examines the effect of acid-base balance on the nutrition status of peritoneal dialysis (PD) patients. We followed 43 PD patients for one year. Blood chemistries were measured monthly. Patients were divided on the basis of subjective global assessment (SGA) into well-nourished (A), mildly-to-moderately malnourished (B), and severely malnourished (C) groups. Mean serum bicarbonate and albumin concentrations were, for group A (n = 16), 23.5 mmol/L and 3.96 g/dL respectively; for group B (n = 17), 27.2 mmol/L and 3.50 g/dL respectively; and for group C (n = 10), 25.9 mmol/L and 2.9 g/dL respectively. In group A, mean serum bicarbonate was significantly lower, and albumin concentration significantly higher as compared with the other groups. Interestingly, of 9 patients with serum HCO3 < 22 mmol/L, 6 were in group A and 2 were in group B. Of 6 patients with serum HCO3 > 29 mmol/L, 5 were in group B and 4 were in group C. The data suggest that well-nourished PD patients tend to be more acidotic. Malnutrition in alkalotic PD patients may be due to low protein intake resulting in decreased acid production; however, an effect of alkalosis on protein metabolism cannot be excluded.