DIAGNOSTIC VALUE OF BIOMARKERS OF ACUTE KIDNEY INJURY DEVELOPMENT AFTER CARDIAC SURGERY PERFORMED IN THE CONDITIONS OF CARDIOPULMONARY BYPASS

Objectives. To assess the diagnostic value of urinary lipocalin associated with neutrophil gelatinase (uNGAL) as a monomarker, as well as in combination with other indicators, in acute kidney injury (AKI) diagnosing in the early postoperative period in cardiac surgery patients. Material and methods. The analysis of 73 case histories of ICU patients after cardiac surgery in the conditions of cardiopulmonary bypass was performed. AKIN criteria were applied to diagnose AKI. The primary end point of the study was the postoperative level of uNGAL, the secondary end point was the indexed value of uNGAL. Results. 31 (42.4%) patients developed AKI (according to AKIN score). uNGAL had a very good level of diagnostic significance in detecting AKI (AUC 0.849, p=0.001) and its optimal cutoff level was more than 48.2 ng/ml within the time frame up to 12 hours after surgery. The diagnostic efficiency of the uNGAL test was: specificity - 88.1%, sensitivity - 67.74%, positive predictive value - 80.8%, negative predictive value - 78.7%, positive likelihood ratio - 5.57, negative likelihood ratio - 0.37. The ratio of uNGAL to leukocytes in the terms up to 12 hours after surgery demonstrated an excellent level of diagnostic value (AUC 0.920, p=0.001). The diagnostic efficiency of this indicator (more than 5.5 μg/1*109) was: specificity - 94.74%, sensitivity - 73.68%, positive predictive value - 93.3%, negative predictive value - 78.3%, positive likelihood ratio - 14.0, negative likelihood ratio - 0.28. Conclusions. The diagnostic capabilities of uNGAL in detecting AKI in the early stages after cardiac surgery exceed the capabilities of serum creatinine traditionally used for this purpose. To improve the efficiency of AKI diagnosis in the early postoperative period, it is possible to use indexed indicators, for example, the ratio of uNGAL to leukocytes level in the patient’s blood.