Diagnostic and prognostic significance of an increase in fractional protein clearance ratio before and during rejection of renal transplant.

We measured prospectively changes in fractional protein clearance ratio (CPr/CCr) in 21 live-related (LR) and 41 cadaver donor (CD) renal transplants before and during onset of first rejections. Fifty-three recipients manifested a rejection within the first post-transplant month. Fractional protein clearance increased in all patients during rejection. An increase in CPr/CCr prior to other evidence of impending rejection, and therefore clinically useful, required at least a 10-day rejection-free interval dated from onset of diuresis (whether diuresis was immediate or delayed by acute tubular necrosis (ATN)). Twenty-three of 25 nonantilymphocyte globulin (ALG)-treated CD transplants manifested clinical and laboratory signs of the first rejection episode prior to the 10th day of diuresis compared with 5 of 21 LR and none of 16 ALG-treated CD transplants. Persistence of elevated CPr/CCr despite treatment forecast graft loss (11 of 13), whereas a decrease in this ratio was associated with ultimate reversal of the rejection process.