Emerging biomarker for predicting acute kidney injury after cardiac surgery: cystatin C

Background/aim: Cardiopulmonary bypass (CPB)-associated acute kidney injury (AKI) is a common situation and rapid diagnosis and risk classification are important in the prevention and management of AKI. Changes in serum creatinine (SCr) levels in the current consensus criteria do not allow clinicians to diagnose CPB-associated AKI until 48 h after surgery.

Materials and methods: We conducted a prospective single center study involving 57 patients who underwent cardiac surgery with CBP to compare serum beta-trace protein (BTP), neutrophil gelatinase-associated lipocalin-2 (NGAL), and cystatin C (CysC) levels with SCr for early diagnosis of CPB associated AKI. We defined AKI according to KDIGO criteria.

Results: AKI was diagnosed in 24 (42.1%) patients. Mean duration of postoperative intensive care unit stay was 4.79 (± 6.12) days for the AKI+ group and 2.15 (± 0.56) days for the AKI– group. The average length of hospital stay was 8.13 (± 5.75) days for the AKI+ group and 7.21 (± 3.68) days for the AKI– group, which was significantly longer in the AKI+ group (P < 0.001, P = 0.011). Unlike other biomarkers, a significant increase in postoperative CysC levels was always found in patients with AKI during follow-up when compared to patients in whom AKI did not develop (P < 0.001).

Conclusion: Increase in serum CysC levels showed a significant positive correlation with increase in SCr levels. We have not seen this correlation between other biomarkers and SCr. According to our study, serum CysC was a reliable biomarker that may aid in the early detection and follow-up of AKI after cardiac surgery.