The deleterious effect of metabolic acidosis on nutritional status of hemodialysis patients

One of the main causes of protein-energy malnutrition in patients on maintenance hemodialysis (MHD) is metabolic acidosis. The aim of this study was to evaluate the effect of metabolic acidosis on nutritional status in a group of MHD patients with adequately delivered dialysis treatment. Of 165 eligible anuric MHD outpatients with Kt/V ≥ 1 and no underlying inflammatory diseases,47 subjects were enrolled. In order to evaluate the effect of different parameters on serum albumin,we measured the pre-dialysis serum albumin,blood pH,serum bicarbonate (HCO 3- ),Kt/V,normalized protein catabolic rate (nPCR) and body mass index (BMI) in these patients. The mean age of the study patients was 55 ± 13.8 years; there were 22 females and six diabetics. The average Kt/V was 1.22 ± 0.16,pH was 7.40 ± 0.15,serum HCO 3- was 23.18 ± 2.38 mEq/L,serum albumin was 4.03 ± 0.56 g/dL,nPCR was 1.00 ± 0.16 g/kg/day,post-dialysis body weight was 58.50 ± 11.50 kg and BMI was 23.47 ± 2.70 kg/m 2 . There was a statistically significant direct correlation between serum albumin and BMI (r = 0.415,P = 0.004),and between serum albumin and serum HCO 3 (r = 0.341,P = 0.019). On multiple regression analysis,the predictors of serum albumin were serum HCO3- and BMI (direct effect) and nPCR (inverse effect). In 17 patients on MHD with serum HCO3- 22 mEq/L,there was a significant inverse correlation between HCO 3 and nPCR (r = 0.492,P = 0.045),and these patients had significantly lower serum albumin compared with patients with serum HCO3- 22 mEq/L (P = 0.046). These data demonstrate that patients on MHD with metabolic acidosis had a lower serum albumin concentration despite adequate dialysis treatment. The inverse effect of nPCR on serum albumin concentration in acidotic MHD patients may be due to hypercatabolism in the setting of metabolic acidosis,leading to deleterious effects on the nutritional status of patients on MHD.