Significance of urine diagnostic tests after renal transplantation

Validity, reliability and clinical value of classical urinary parameters for transplant monitoring are controversial. Urinary parameters were analyzed regarding cost-effectiveness, frequency of urinary tract infection and prediction of renal graft function and rejection.

Urinary parameters of the first two postoperative weeks of 120 renal transplant patients were retrospectively correlated with the postoperative course.

Creatinine levels were significantly different on each postoperative day between the groups with and without rejection. Osmolaluria, diuresis and serum creatinine are equivalent in predicting graft rejection. Osmolaluria is not suitable as a distinguishing criterion between graft rejection and other complications. Measurement of glucosuria has no diagnostic value. Proteinuria has no prognostic relevance regarding rejection, although proteinuria >0.5g/l occurred more often in patients with rejection. Despite antibiotic prophylaxis with co-trimoxazole, 41 of 120 patients (34%) suffered from urinary tract infection (UTI; mostly E. coli) within the first 14 days after transplantation.

The measurement of some classical urinary parameters delivers no diagnostic gain. UTIs are frequent despite antibiotic prophylaxis, but the use of urine cultures makes sense only if a (cheaper) semiquantitative test is positive.