Metabolomic Profiling of Amino Acids in Patients with End-stage Renal Disease Undergoing Scheduled Hemodialysis

Abstract

The objective: to comprehensively assess the amino acid profile in patients with end-stage renal disease undergoing scheduled hemodialysis (HD), to determine the nature and extent of changes in the concentrations of individual amino acids (AA) and their ratios, and to identify associations with clinical, anthropometric, and laboratory parameters, as well as parameters of dialysis therapy efficacy. Materials and methods. A single-center cohort study with retrospective and prospective analysis was conducted involving 20 patients. We assessed medical history, anthropometric, and laboratory parameters, as well as the amino acid profile, including the determination of AA, particularly branched-chain amino acids, aromatic AA, and those involved in arginine (Arg) metabolism and the urea cycle. Results. The most common abnormalities were elevated citrulline (Cit) levels in 80.0% of patients and tryptophan (Trp) deficiency in 65.0% of patients. Leucine (Leu) and valine (Val) correlated positively with serum albumin levels and body mass index (BMI); a sum of Leu and Val < 216.2 μmol/L was associated with an increased risk of low albumin levels (< 38 g/L). Phenylalanine was associated with the intensity of dialysis therapy, changes in phosphorus and body weight, while Trp was associated with age, uric acid, parathyroid hormone, and phosphorus. Arg and ornithine (Orn) were associated with dialysis duration, BMI, and HD dose, respectively. The derived indices Arg/Orn and Cit/Arg proved to be more informative than the absolute concentrations of individual AA. Conclusions. Patients undergoing scheduled HD develop a characteristic profile of amino acid metabolism disorders. The use of amino acid index derivatives may complement the assessment of the metabolic and nutritional status of patients undergoing hemodialysis.