The level of the biomarkers at the time of nephrology consultation might predict the prognosis of acute kidney injury in hospitalized patients.

Introduction: The value of biomarkers at the time of nephrology consultation in predicting the prognosis of acute kidney injury (AKI) in hospitalized patients has not been well described. This study aimed to evaluate the possibility of biomarkers at the time of nephrology consultation in predicting the prognosis of AKI.

Methods: We prospectively enrolled 103 hospitalized patients who developed AKI. Urinary Neutrophil Gelatinase Associated Lipocalin (NGAL), IL-6, IL-18, N-Acetyl-β-D-Glucosaminidase (NAG), and serum Cystatin C (CysC) were measured at the time of nephrology consultation. Baseline values of serum creatinine (bScr), serum creatinine on consultation (cScr) and the peak level of serum creatinine (pScr) were recorded. All the patients were followed-up till 28 days since consultation. Serum and urinary levels of the biomarkers were compared according to the patient or kidney prognosis. Each marker was assessed for its predictive value using receiver operator characteristic (ROC) curves to predict AKI prognosis.

Results: Patients were aged 54.28 ± 19.05. Male patients constituted 65% of the study group and baseline Scr was 93.54 ± 35.98 μmol/l. The mortality rate of the patients was 25.2% and kidney loss rate was 18.8% at 28 days after consultation. The level of urinary NGAL was significantly higher in death patients than that in survival patients [147.00 (31.59, 221.87) μg/ml vs. 22.43 (6.48, 89.77) μg/ml, p = 0.001], while the level of bScr, cScr, pScr, urinary IL-6 and NAG were similar in both these groups. The AUC of urinary NGAL for predicting patients' death was 0.723 (p = 0.001). Serum CysC and urinary IL-18 concentration was higher in the death patients with a marginal p value (p = 0.065 and 0.059 respectively). All the urinary markers, including NAG, NGAL, IL-6 and IL-18 were significantly higher in patients with kidney loss than in those with kidney survival, while no difference was found in Scr and serum CysC levels. The AUCs of these urinary biomarkers for predicting kidney survival were 0.663, 0.655, 0.705 and 0.663 respectively (p < 0.05). The concentrations of cScr, pScr, serum CysC, urinary IL-6 and NGAL were significantly higher in RRT patients (p < 0.05). The AUCs for predicting RRT were 0.628, 0.781, 0.768, 0.672 and 0.775 respectively.

Conclusions: The level of biomarkers at the time of nephrology consultation might predict the prognosis of AKI in hospitalized patients. Further studies should be done to understand the role of the serum and urinary markers in the prognosis of AKI.