Progression of urinary protein excretion after kidney transplantation: A marker for poor long-term prognosis

Introduction: Post-transplantation proteinuria is a risk factor for graft failure. A progressive decline in renal graft function is a predictor for mortality in kidney transplant patients. Objectives: To assess the development and the progression of urinary protein excretion (UPE) in the first year post-transplant in recipients of kidney transplants and its effect on patient and graft outcomes. Materials and methods: We analysed 1815 patients with 24-h UPE measurements available at 3 and 12 months post-transplant. Patients were divided based on their UPE level: below 300 mg, 300–1000 mg and over 1000 mg (at 3 and 12 months), and changes over time were analysed. Results: At 3 months, 65.7% had UPE below 300 mg/24 h, 29.6% 300–1000 mg/24 h and 4.7% over 1000 mg/24 h. At one year, 71.6% had UPE below 300 mg/24 h, 24.1% 300–1000 mg/24 h and 4.4% over 1000 mg/24 h. In 208 patients (12%), the UPE progressed, in 1233 (70.5%) it remained stable and in 306 (17.5%) an improvement was observed. We found that the level of UPE influenced graft survival, particularly if a progression occurred. Recipient's age and renal function at one year were found to be predictive factors for mortality, while proteinuria and renal function were predictive factors for graft survival. Conclusions: Proteinuria after transplantation, essentially when it progresses, is a marker of a poor prognosis and a predictor for graft survival. Progression of proteinuria is associated with poorer renal function and lower graft survival rates.