Impact of kidney function on plasma troponin concentrations after coronary artery bypass grafting.

BACKGROUND: To date, there have been no studies reliably showing an influence of the kidney on the concentration of troponins. We therefore analysed the concentration curves in patients after coronary artery bypass grafting (CABG) according to their dependence on renal function.

METHODS: We determined cardiac troponin I (cTnI), cardiac troponin T (cTnT) and creatinine in plasma in 28 patients after CABG. Discrimination into patients with normal (n=13) and impaired (n=15) renal function was based on creatinine clearance (Crea-Clear). The curves for cTnI and cTnT, as recorded by post-operative measurements, were approximated using mathematical functions. The curve parameters peak maximum (P(max)), peak position (P(pos)), half-height breadth (HHB) and area under the curve (AUC) were established after this. Assuming an exponential function, the half-life (t(1/2)) of cTnI was determined from the declining part of the curve.

RESULTS: For both, cTnI and cTnT, significant differences in P(max), P(pos), HHB and AUC were detected after curve approximation. The t(1/2) values of cTnI were 25.1 h (22.0-35.3) for the group with normal renal function and 38.4 h (35.9-51.9) for patients with impaired renal function (P=0.001). An influence of diabetes mellitus (Dm), renal replacement therapy or the age of the patients could not be verified.

CONCLUSION: The results of this study clearly demonstrate that kidney function has an impact on plasma troponin concentrations. In everyday clinical practice this has to be considered when interpreting elevated plasma troponin concentration in patients with impaired renal function.