60 heart valve replacement patients were enrolled, and 26 of them had low-dose corticosteroid treatment on the first 3 days postoperatively. Serum creatinine, serum cystatin C and 24-h creatinine clearance rate (CCR) adjusted by body surface area were determined preoperation, days 1, 2, 3, 7 post operation.
Serum creatinine increased and peaked at day 3 postoperatively, while cystatin C peaked at day 2, and the adjusted CCR also reached a minimum at day 2. The inverse of cystatin C correlated better with CCR than that of creatinine (r = 0.751 vs. 0.629). Using adjusted CCR as “golden standard”, cystatin C was superior to creatinine in diagnosing renal dysfunction (area under the curve [AUC] for cystatin C 0.876, 95 % confidence interval 81.8–93.4; AUC for creatinine 0.801, 95 % confidence interval 72.5–87.7; p = 0.045). Low-dose corticosteroid treatment has no significant effect on cystatin C.
In agreement with many other investigators, the present findings support cystatin C is a reliable marker of renal function. It is superior to creatinine in patients post CPB.