Albumin and urine albumin–Creatinine ratio as acute kidney injury predictors in patients undergoing cardiac surgery

Context: Postoperative acute kidney injury (AKI) is associated with increased morbidity and mortality in patients undergoing cardiac surgery. Aim: The aim of the present study is to compare preoperative and postoperative serum albumin levels, urine albumin–creatinine ratio (UACR), and estimated glomerular filtration rate (eGFR) in patients undergoing cardiac surgery as a predictor of AKI. Settings and Design: The prospective study was conducted at cardiothoracic unit in the individuals of age 40–70 years admitted for coronary artery bypass grafting. Materials and Methods: The study participants admitted for cardiac surgery with normal serum creatinine value of 0.3–1.3 mg/dl were included. Preoperative and postoperatively (days 1 and 3 after cardiac surgery) parameters such as serum albumin, creatinine, and UACR were analyzed. Baseline serum creatinine >1.6 mg/dl was excluded. eGFR was calculated with Cockcroft's formula and categorized as Group A with eGFR <60 ml/min and Group B with eGFR ≥60 ml/min. Results: Mean UACR compared to baseline was found to be increased progressively on day 1 and day 3 postoperative period after cardiac surgery. Compared with baseline data, albumin levels were found to be decreased during postoperative phase. eGFR reflected the risk of kidney damage as it gets decreased by 15% on day 1 after cardiac surgery. Receiver operating characteristic curve analysis of albumin and UACR revealed sensitivity and specificity that predicts lowered eGFR. Conclusion: Decreased serum albumin and increased UACR after cardiac surgery reflected with lowered eGFR indicate the renal injury after cardiac surgery. Serum hypoalbuminemia and UACR are predictors of AKI in the postoperative phase.