Neutrophil Gelatinase-associated Lipocalin, Cystatin C and Matrix Metalloproteinase-9 as Possible Biomarkers in Early Detection of Acute Kidney Injury after Cardiac Surgery

Abstract

Introduction: Acute Kidney Injury (AKI) often occurs after open heart surgery. Today, serum creatinine is used as an indicator for identifying AKI; however, creatinine is unreliable due to delay in its elevation. Therefore, more reliable markers are required for early diagnosis of AKI. Aim: To measure the changes in Neutrophil GelatinaseAssociated Lipocalin (NGAL) and Cystatin C (Cys C) levels and Matrix Metallo Proteinase 9 (MMP-9) activity in serum of patients who underwent cardiac surgery. Materials and Methods: The present descriptive study was conducted from September to October 2015 among patients referred to Cardiovascular Surgery Center at Shahid Modarres Hospital in Tehran, Iran. Urine and serum sample from 29 candidates for cardiac surgery were collected at 6 and 12 hours after surgery. On the basis of increase in serum creatinine, the patients were divided into two groups; AKI and control group. AKI group had at least 50% increase in serum creatinine; those with less than 50% increase were considered as control group. Urine NGAL and Cys C concentrations were measured using ELISA; MMP-9 activity was determined using gel zymography. Results: The results showed an increase in Cys C concentration in AKI group compared to control group after 6 and 12 hours of surgery. The comparison of Cys C concentration in AKI group between 6 and 12 hours after surgery showed no significant difference. The comparison of NGAL at 12 hours after surgery between control and AKI groups showed no significant difference. The MMP-9 activity showed a decreasing trend in AKI group compared to control group at 12 hours after surgery. Decrease in MMP-9 activity in AKI group at 6 hours after surgery was statistically different from after 12 hours of surgery. Conclusion: Present results provide evidence that Cys C and MMP-9 can be better reliable markers for early detection of AKI as compared to serum creatinine, after cardiac surgery. NGAL did not show higher sensitivity compared to creatinine in these patients. Therefore, Cys C and MMP-9 can be suggested as biomarkers for early detection of AKI after cardiac surgery.

Keywords

• cardiac surgery
• creatinine
• gel zymography