A retrospective study of the relationship between postoperative urine output and one year transplanted kidney function

BACKGROUND: Kidney transplantation (KT) is the most obvious method of treating a patient with end-stage renal disease. In the early stages of KT, urine production is considered a marker of successful reperfusion of the kidney after anastomosis. However, there is no clear conclusion about the relationship between initial urine output after KT and 1-year renal function. Thus, we investigated the factors that affect 1-year kidney function after KT, including urine output. METHODS: This retrospective study investigated the relationship between urine output in the 3 days after KT and transplanted kidney prognosis after 1-year. In total, 291 patients (129 living-donor and 162 deceased-donor transplant recipients) were analyzed; 24-h urine volume per body weight (in kilograms) was measured for 3 days postoperatively. The estimated glomerular filtration rate (eGFR), determined by the Modification of Diet in Renal Disease algorithm, was used as an index of renal function. Patients were grouped according to eGFR at 1-year after KT: a good residual function group, eGFR ≥60, and a poor residual function group, eGFR < 60. RESULT: Recipients’ factors affecting 1-year eGFR include height (P = 0.03), weight (P = 0.00), and body mass index (P = 0.00). Donor factors affecting 1-year eGFR include age (P = 0.00) and number of human leukocyte antigen (HLA) mismatches (P = 0.00). The urine output for 3 days after KT (postoperative day 1; 2 and 3) was associated with 1-year eGFR in deceased-donor (P = 0.00; P = 0.00 and P = 0.01). And, postoperative urine output was associated with the occurrence of delayed graft function (area under curve (AUC) = 0.913; AUC = 0.984 and AUC = 0.944). CONCLUSION: Although postoperative urine output alone is not enough to predict 1-year GFR, the incidence of delayed graft function can be predicted. Also, the appropriate urine output after KT may differ depending on the type of the transplanted kidney. TRIAL REGISTRATION: Clinical Research Information Service of the Korea National Institute of Health in the Republic of Korea (KCT0003571).