Stable Cystatin C Serum Levels Confirm Normal Renal Function in Patients With Dronedarone-Associated Increase in Serum Creatinine
What is the role of serum cystatin C as a biomarker for the estimation of true renal function in patients receiving dronedarone for nonpermanent atrial fibrillation (AF)?
This was a prospective study of 20 patients with nonpermanent AF in whom dronedarone 400 mg twice daily was started. Serum cystatin C and creatinine clearance were measured before treatment and 10 and 90 days following treatment.
Mean serum creatinine level for all 20 patients at baseline was 84.55 ± 12.14 and 87.8 ± 17.59 µmol/L on day 10. Among the five patients who had an increase in serum creatinine level >1 standard deviation, there was a significant elevation of creatinine levels from day 0 to day 10 (82.4 ± 9.18 to 104.4 ± 12.74 µmol/L; p = 0.003). Serum cystatin C levels remained stable in all patients. The creatinine and cystatin C levels after 3 months did not show any significant differences, neither compared with baseline values nor in the two groups of increased creatinine and not increased creatinine.
The authors concluded that serum cystatin C may be a reliable biomarker for the estimation of true renal function early in the course of initiation of treatment with dronedarone.
The significance of this prospective analysis is limited by the very small number of participants. Nonetheless, this study draws attention to the observation that the increase in serum creatinine levels that may be seen soon after the start of treatment with dronedarone is related to inhibition of the organic cation transporter responsible for the tubular secretion of creatinine. As the elimination of cystatin is completely dependent on glomerular filtration and unaffected by changes in tubular secretion, this biomarker may represent a more reliable measure of renal function of those taking dronedarone. The findings from this small study warrant further exploration and confirmation. The potential higher laboratory costs associated with monitoring serum cystatin C levels cannot be dismissed.
Keywords: Troponin I, Cardiology, Glomerular Filtration Rate, Creatinine, Cystatin C
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