Serum uric acid may predict development of progressive acute kidney injury after open heart surgery

Objectives: Acute kidney injury (AKI) is a common complication of cardiac surgery developing in 25-35% cases. Recently, neutrophil gelatinase-associated lipocalin (NGAL) was shown to predict AKI development earlier than serum creatinine. Some studies demonstrated the predictive role of post-operative serum uric acid (SUA) as an early marker of AKI. We aimed to study the role of serum and urine NGAL as well as SUA to predict progression of AKI. Design and methods: This is a prospective observational study of patients undergoing cardiac surgery. Blood and urine samples for measurement of uric acid, serum and urine NGAL levels were collected prior to cardiac surgery (0h), and in the time course at 2nd and 24th hours after surgery. Patients who developed AKI were divided into two subgroups as progressing and non-progressing AKI. Results: Sixty patients (42 males, 18 females) were included. After cardiac surgery, 40 patients developed AKI, 20 of whom non-progressing AKI, and 20 progressing AKI. All of the markers significantly increased in AKI patients. A receiver operator characteristics (ROC) curve analysis showed higher predictive ability of SUA for progressing AKI compared with serum and urine NGAL. When compared markers obtained at the second hour after surgery, UA had significantly large AUC than NGAL to predict AKI developed at 24 and 48h, particularly in patients, who require renal replacement therapy (RRT). Conclusion: Uric acid seems to predict the progression of AKI and RRT requirement in patients underwent cardiac surgery better than NGAL.