Urinary protein/creatinine ratio as an indicator of allograft function following live related donor renal transplantation

Abstract

In a study of 656 urine specimens from 53 consecutive recipients of live related donor renal allografts we found an excellent correlation between the protein content of 24-h urines and protein/creatinine ratio (Up/Ucr) in overnight urine samples. Using this ratio, we evaluated proteinuria up to 180 days after renal transplantation (overnight urine samples analysed, n = 2745). Heavy proteinuria in the immediate post-operative period had no prognostic significance. Eighty-nine percent of all clinically observed acute rejection episodes were accompanied by an increase over baseline of Up/Ucr; in 56.5% of these episodes elevation of Up/Ucr preceded that of serum creatinine. However, as a marker of rejection the usefulness of this parameter was limited owing to large number of false positive elevations. In 50 recipients whose grafts survived for more than 3 mth, proteinuria was graded into minimal, moderate and heavy. Renal function at the end of six months was good in all patients who exhibited proteinuria with Up/Ucr less than 100 mg/mmol creatinine. Persistent proteinuria with Up/Ucr above 100 mg/mmol preceded significant deterioration of graft function. Therefore, a protein-creatinine ratio of 100 mg/mmol can be considered as an apparent cut-off to differentiate stable from deteriorating graft function in long term evaluation of transplant recipients.