Diagnostic value of urinary N-acetyl-β-d-glucosaminidase, its isoenzymes and the fractional excretion of sodium following renal transplantation

Daily total urine N-acetyl-β-d-glucosaminidase activity, isoenzyme profile and fractional excretion of sodium were measured in 13 consecutive renal transplant patients. Rejection episodes were clinically diagnosed in 12 patients, 11 of whom (92%) showed an increased enzymuria either before or during the onset of clinical signs. The ratio of the two major isoenzymes (A/B) fell during 10 episodes (83%) and in six of these (50%) increased levels of the minor isoenzyme forms were observed. Increased fractional excretion of sodium was associated with nine (75%) of the episodes. Increased fractional excretion of sodium with a raised total enzymuria accompanied by a reduced A/B ratio and an increased proportion of the minor isoenzyme forms occurred in eight (67%) of the rejection episodes. The use of these measurements in the diagnosis of episodes of acute rejection in renal transplantation is discussed.