Enzymuria and low molecular weight protein excretion as the differentiating marker of complications in the early post kidney transplantation period

Renal function in the early post-transplantation period depends largely on factors affecting the kidney prior to implantation. Function of the graft may be also disturbed by the most common complications of the early post-operative period such as acute graft rejection (AGR), acute tubular necrosis (ATN) and may be modified by nephrotoxic action of cyclosporine A (CsA). Evaluation of excretion of enzymes and low molecular weight proteins (LMWP) may help in the differentiation of these complications. Aim Comparison of the urinary excretion of markers of tubular injury in patients with AGR, ATN, or patients with stable graft function (SGF) was made and differences between groups and correlations between markers and cold ischemia time (CIT), warm ischemia time (WIT) and blood trough level of cyclosporine A (CsA₀) were determined. Material and methods In 60 cadaveric renal allograft recipients in the early post-transplantation period urinary excretion of N-acetyl-β-d-glucosaminidase (NAG) and B isoenzyme (NAG-B), alanylaminopeptidase (AAP), γ-glutamyltransferase (GGT), α and π isoenzymes of glutathione S-transferase (α-GST, π-GST), retinol binding protein (RBP) and β2- microglobulin (β2M), were analyzed. Results NAG and NAB-B activities were higher in ATN (P<0.05, P<0.01) and in AGR (P<0.005, P<0.02) than in SGF. Excretion of π-GST was higher in AGR than in SGF (P<0.0002) or ATN (P<0.007). CIT and WIT in patients with ATN were higher (P<0.05) than in SGF group. In ATN patients, correlations of CIT with RBP (P<0.05) and π-GST (P<0.05), and WIT with RBP (P<0.05), and π-GST (P<0.001) were found. Conclusions High urinary NAG and NAG B excretion characterizes ATN and AGR patients. Evaluating urinary excretion of π-GST may be helpful in differentiating AGR from ATN. However, taking into account ischemia time is necessary in interpreting the π-GST value in early post transplant period.