Profile of serum amino acids in patients on peritoneal dialysis

Abstract

Patients on peritoneal dialysis (PD) are predisposed to disturbances in amino acid metabolism and development of malnutrition which are unfavorable prognostic factors. Studying the serum level of essential amino acids in patients on PD. The total of 56 PD patients (mean age 42.4±11.5 years, treatment duration 24.0±14.2 months) was examined simultaneously with 12 practically healthy volunteers (mean age 39.4±10.7 years). Analysis of the dietary interviews and 3-day dietary journals was carried out. The levels of essential and conditionally essential amino acids in both serum and daily volume of peritoneal dialysis solution were determined using liquid chromatography. Dietary protein consumption in PD patients was 1.06±0.09 vs. 1.21±0.05 g/kg/day (р<0.05) in the control group. Decreased serum levels of 6 essential amino acids were registered (valine, lysine, threonine, and tyrosine – almost 2 fold (р<0.05), leucine and isoleucine – by 28 and 34% (р<0.05), accordingly, as well as normal concentration of phenylalanine and methionine – 0.6±2.3 and 9.4±2.1 mg/L, correspondingly, vs. 11.1±0.8 and 11.3±0.8 mg/L in the control (р>0.05), and increased level of histidine – 32.7±6.8 vs. 14.6±0.5 mg/L in the control. The ratios essential/nonessential amino acids and branched/replaceable amino acids as well as Fisher’s index were 0.54±0.05, 0.25±0.05 and 2.0±05, correspondingly, vs. 1.35±0.15, 0.55±0.05 and 3.2±0.2 in the control (р<0.05). Daily excretion of essential amino acids with dialysis solution fluctuated between 314 and 522 mg, and that of conditionally essential amino acids – between 156 and 337 mg. Direct correlation was revealed between daily excretion of essential amino acids, on the one hand, and both peritoneal transport (р=0.001) and daily excretion of isoleucine, threonine, histidine, and their serum levels, on the other (р=0.04, р=0.001, and р=0.01, accordingly). Direct correlation between daily excretion of essential amino acids and that of tyrosine and its serum level was only near reliable value (р=0.055). PD patients are characterized by the markedly unbalanced level of essential amino acids. The deficiency of the majority of essential amino acids in PD patients is due to their high loss through dialysis solution and insufficient protein consumption.