Urinary Biomarkers Improve the Diagnosis of Intrinsic Acute Kidney Injury in Coronary Care Units

Acute kidney injury (AKI) is associated with increased morbidity and mortality and is frequently encountered in coronary care units (CCUs). Its clinical presentation differs considerably from that of prerenal or intrinsic AKI. We used the biomarkers calprotectin and neutrophil gelatinase-associated lipocalin (NGAL) and compared their utility in predicting and differentiating intrinsic AKI. This was a prospective observational study conducted in a CCU of a tertiary care university hospital. Patients who exhibited any comorbidity and a kidney stressor were enrolled. Urinary samples of the enrolled patients collected between September 2012 and August 2013 were tested for calprotectin and NGAL. The definition of AKI was based on Kidney Disease Improving Global Outcomes classification. All prospective demographic, clinical, and laboratory data were evaluated as predictors of AKI. A total of 147 adult patients with a mean age of 67 years were investigated. AKI was diagnosed in 71 (50.3%) patients, whereas intrinsic AKI was diagnosed in 43 (60.5%) of them. Multivariate logistic regression analysis revealed urinary calprotectin and serum albumin as independent risk factors for intrinsic AKI. For predicting intrinsic AKI, both urinary NGAL and calprotectin displayed excellent areas under the receiver operating characteristic curve (AUROC) (0.918 and 0.946, respectively). A combination of these markers revealed an AUROC of 0.946. Our result revealed that calprotectin and NGAL had considerable discriminative powers for predicting intrinsic AKI in CCU patients. Accordingly, careful inspection for medication, choice of therapy, and early intervention in patients exhibiting increased biomarker levels might improve the outcomes of kidney injury.