Evaluation of amino acid clearances in post-transplant kidney patients stratified by eGFR

The human kidney has a prominent role in the metabolism of amino acids and the control of plasma concentrations. Treatment modalities, such as kidney transplantation, hemodialysis, etc., may alter amino acid concentrations. In the present study, we aimed to evaluate the effect of kidney transplantation on the amino acid profile and the relationship between creatinine clearance and amino acid clearances in post-transplant kidney patients. Serum and urine samples were obtained from 133 patients after kidney transplantation. Patients were divided into three groups based on eGFR. Amino acid profiles were performed by liquid chromatography coupled with tandem mass spectrometry, and clearances were calculated using the 24-hour creatinine clearance formula. The amino acid clearances between the studied groups differed significantly in 10 of the 27 amino acids. While 1-methyl-l-histidine, 3-methyl-lhistidine, Arginine, Cystine, Ethanolamine, Glycine, L-Histidine, Isoleucine, and Taurine significantly showed an upward trend, L-Proline especially revealed a downward trend. Amino acid clearances that showed the strongest correlation with creatinine clearance were 1-methyl-l-histidine, 3-methyl-l-histidine, and ethanolamine. However, Arginine and L-proline had a weak positive and negative linear relationship, respectively. This study showed that amino acid clearances varied in kidney transplant patients among the studied groups. Increased or decreased amino acid clearances are affected by the progression of renal dysfunction. These results give insight into kidney transplantationassociated modifications of amino acid metabolism.