Clinical significance of proteinuria at posttransplant year 1 in kidney transplantation

Purpose

Proteinuria in the nontransplant population is a progressive renal disease. We analyzed the prevalence and clinical significance of proteinuria as well as factors related to its degree at posttransplant year 1 among kidney transplant recipients.

Methods

We measured protein in a 24-hour urine among 644 recipients from January 1996 to December 2010.

Results

Among 372 male and 272 female recipients, the mean amount of urinary protein was 424.4 ± 1010 mg/d (range, 13.88-8691) including 388 (60.2%) subjects with microproteinuria and the other 256 (39.8%) with overt proteinuria. Nephrotic range proteinuria was observed in 17 (2.6%) and nonnephritic range proteinuria, in 239 (37.1%) recipients. The latter cohort was categorized into low-grade proteinuria (n = 224; 34.8%) and high-grade proteinuria (n = 15; 2.3%). Proteinuria at posttransplant 1 year highly correlated with serum creatinine values at posttransplant years 1 and 2 as well as estimated glomerular filtration rate but not creatinine clearance at postoperative year 2. A greater incidence of graft loss was observed among recipients with more severe proteinuria. Males, recipients with anti-hepatitis C virus antibody, unrelated donors, anti-thymocyte immunoglobulin at the time of reperfusion, maintenance immunosuppression with cyclosporine or without mycophenolate mofetil were strongly associated with the amount of proteinuria.

Conclusion

This study demonstrated the prevalence of proteinuria in kidney transplant recipient to be high. The presence as well as level of proteinuria were predictive markers for inferior allograft function.