Serum Concentration of Amino Acids Versus Nutritional Status in Hemodialysis Patients

Abstract

The aim of this study was to evaluate the correlation between the serum concentration of amino acids (AAs) and nutritional status in hemodialysis (HD) patients. This study was performed in 22 HD patients dialyzed for 10 to 288 months, and in a control group of 20 healthy volunteers. Nutritional status was determined by the subjective global assessment method and by measuring albumin concentration. Body composition was determined using the parameters of body mass index, and the percentage of body fat and lean body mass (as measured by the near-infrared method). We measured C-reactive protein (CRP) as a marker of inflammatory status. Serum concentrations of 20 AAs were measured by precolumn orthophtalaldehyde derivatization, applying high-performance liquid chromatography (Hitachi-Merck HPLC, Tokyo, Japan) equipped with a C-18 reversed-phase column and a methanol/acetate buffer gradient. Thirteen of 22 (59%) patients were of good nutritional status, and 9/22 (41%) were malnourished, including 1 person with severe malnutrition. In dialyzed patients compared with control subjects, a decreased concentration of essential and nonessential AAs was observed (P < .05). Concentrations of the majority of studied AAs (16 out of 20) were lower in patients dialyzed for a period >2 years, compared with patients dialyzed for a shorter time. The ratio of branched-chain amino acids (BCAAs) to aromatic AAs was lower in the dialyzed group compared with control subjects. This ratio was also lower in patients dialyzed longer compared with patients dialyzed for <2 years. No correlation between the concentration of some AAs and CRP level or dialysis adequacy was observed. In the malnourished group, an insignificantly lower concentration of some essential AAs (lysine, leucine, isoleucine, valine, and threonine), and a significantly higher (P = .04) concentration of CRP, were observed. Despite quite good nutritional status, dialyzed patients present abnormalities in their AA profiles. Moreover, a significant decrease of BCAA concentration is related to calorie-protein malnutrition, inflammation, and a long period of hemodialysis.