Movilli E, Bossini N, Viola B F, Camerini C, Cancarini G C, Feller P, Strada A, Maiorca R
Division of Nephrology Spedali Civili, University of Brescia, Italy.
Nephrol Dial Transplant. 1998 Mar;13(3):674-8. doi: 10.1093/ndt/13.3.674.
Malnutrition in haemodialysis (HD) patients has been referred to underdialysis with low protein intake, and to acidosis. However, the separate effects of underdialysis and acidosis on nutrition have not been clearly demonstrated. To evaluate the role of the dialysis dose and of metabolic acidosis on nutrition, we measured the predialysis serum HCO3, pH, serum albumin, PCRn, Kt/V, and BMI in 81 uraemic patients on maintenance bicarbonate HD for 93+/-80 months. Patients with chronic liver diseases, malignancies, and cachexia were excluded.
Mean age was 59+/-17 years, Kt/V was 1.29+/-0.21, PCRn 1.06+/-0.22 g/kg/day, serum albumin 4.07+/-0.28 g/dl, BMI 23+/-4 kg/m2, HCO3 21.1+/-1.9 mmol/l, pH 7.36+/-0.04. Serum albumin showed a significant direct correlation with: PCRn (P=0.001), HCO3 (P=0.001), pH (P=0.002), but no correlation with Kt/V and BMI. Serum HCO3 correlated inversely with PCRn (P=0.027). Multiple regression analysis confirmed the significant role of serum bicarbonate and age, but not of Kt/V, on serum albumin concentrations. The role of PCRn appeared to be marginal compared to serum bicarbonate in determining serum albumin levels. Dividing patients into two groups, serum albumin was 3.96+/-0.22 g/dl with HCO3 < or = 20 mmol/l and 4.18+/-0.31 g/dl in those with serum HCO3 > or = 23 mmol/l (P=0.002). PCRn in the same groups was respectively 1.14+/-0.24 g/kg/day and 1.01+/-0.23 g/kg/day (P=0.03). Most importantly, serum albumin levels did not appear to be affected by the dialysis dose, with Kt/V ranging from 0.90 to 1.88.
In HD patients with adequate Kt/V, metabolic acidosis exerts a detrimental effect on serum albumin concentrations partially independently of the protein intake, as evaluated by PCRn. In the presence of moderate to severe metabolic acidosis, PCRn does not reflect the real dietary protein intake of the patients, probably as a result of increased catabolism of endogenous proteins. For this reason PCRn should be considered with caution as an estimate of the dietary protein intake in HD patients in the presence of metabolic acidosis.
血液透析（HD）患者的营养不良被认为与透析不充分及蛋白质摄入不足和酸中毒有关。然而，透析不充分和酸中毒对营养的单独影响尚未得到明确证实。为评估透析剂量和代谢性酸中毒对营养的作用，我们测定了81例接受维持性碳酸氢盐血液透析93±80个月的尿毒症患者透析前的血清HCO3、pH、血清白蛋白、PCRn、Kt/V和BMI。排除患有慢性肝病、恶性肿瘤和恶病质的患者。
平均年龄为59±17岁，Kt/V为1.29±0.21，PCRn为1.06±0.22g/kg/天，血清白蛋白为4.07±0.28g/dl，BMI为23±4kg/m2，HCO3为21.1±1.9mmol/l，pH为7.36±0.04。血清白蛋白与PCRn（P=0.001）、HCO3（P=0.001）、pH（P=0.002）呈显著正相关，但与Kt/V和BMI无相关性。血清HCO3与PCRn呈负相关（P=0.027）。多元回归分析证实血清碳酸氢盐和年龄对血清白蛋白浓度有显著作用，而Kt/V无此作用。在决定血清白蛋白水平方面，与血清碳酸氢盐相比，PCRn的作用似乎较小。将患者分为两组，血清HCO3≤20mmol/l组的血清白蛋白为3.96±0.22g/dl，血清HCO3≥23mmol/l组的血清白蛋白为4.18±0.31g/dl（P=0.002）。相同分组中的PCRn分别为1.14±0.24g/kg/天和1.01±0.23g/kg/天（P=0.03）。最重要的是，血清白蛋白水平似乎不受透析剂量的影响，Kt/V范围为0.90至1.88。
在Kt/V充足的HD患者中，代谢性酸中毒对血清白蛋白浓度产生有害影响，部分独立于通过PCRn评估的蛋白质摄入量。在存在中度至重度代谢性酸中毒的情况下，PCRn可能无法反映患者实际的饮食蛋白质摄入量，这可能是由于内源性蛋白质分解代谢增加所致。因此，在存在代谢性酸中毒的情况下，将PCRn作为HD患者饮食蛋白质摄入量的估计值时应谨慎考虑。
