SPECIFICITY OF CARDIAC TROPONIN-I AND TROPONIN-T IN RENAL-DISEASE

We investigated and compared serum levels of cardiac troponins I(cTnl) and cardiac troponin T (cTnT) in 85 renal patients (chronic renal imp airment n = 23, continuous ambulatory peritoneal dialysis n = 20, hemo dialysis n = 42). Patients with the following conditions were excluded : myocardial infarction, angina pectoris, liver disease, malignant neo plasms, enforced physical activity, skeletal muscle trauma, myositis, rhabdomyolysis and seizures. Troponin T was measured by the second gen eration cTnT-ELISA with a cutoff value = 0.1 mu g/l. Troponin I was me asured by a cTnl immunoassay analyser with a cut-off value = 2.0 mu g/ l. Additionally, creatine kinase (CK), CK-MB activity, CKMB mass conce ntration and myoglobin levels were measured. Specificity was determine d as the fraction of true-negative cases compared to the total number of false-positive and true-negative cases. Specificity for cTnT was 96 % [78-100] in patients with renal impairment (creatinine > 150 mu mol/ l), 95% [75-100] in continuous ambulatory peritoneal dialysis patients , but in hemodialysis patients it was 75% [53-92] for short-term hemod ialysis (< 1 year) and 46% [24-68] for long-term hemodialysis (> 1 yea r). There was a weak correlation between cTnT levels and duration of h emo dialysis therapy (r = 0.35, n = 34, p < 0.04). Specificity for cTn l in renal impairment patients was 96% [78-100] and 100% [84-100] in c ontinuous ambulatory peritoneal dialysis and all hemodialysis patients . None of the studied markers showed higher specificity than cTnl. Onl y myoglobin was less specific than cTnT in hemodialysis patients. Diff erent clearances of the troponins during dialysis (investigated by pre -hemodialysis and post-hemodialysis levels) cannot explain the discord ant results of cTnT and cTnl. Conclusion: Cardiac troponin I exhibits higher specificity than cardiac troponin T in hemodialysis patients. U remic myopathy could explain falsely elevated troponin T levels in hem odialysis patients.