Diagnostic significance of urinary enzymes in detecting acute rejection crises in renal transplant recipients depending on expression of results illustrated through the example of alanine aminopeptidase.

In 82 renal transplant recipients we measured the excretion of urinary alanine aminopeptidase (EC 3.4.11.2) activity daily after transplantation until patients' discharge from hospital. Enzyme excretion was expressed as volume activity (U/L), time-related output (U/4h) and in relation to the excreted creatinine. Diagnostic sensitivity, specificity, efficiency and likelihood ratios were calculated from all three expressions with regard to diagnosis of acute rejection crises. The term "enzyme activity per creatinine excreted" has the highest diagnostic potential.