Novel biomarkers in acute kidney injury: their role in the diagnosis of kidney dysfunction and etiology definition, their potential as predictive markers of structural renal damage severity.

Acute kidney injury (AKI) is a life-threatening condition whose early diagnosis is crucial. The most used method to evaluate renal function is the glomerular filtration rate (eGFR). The detection of new circulating molecules has gained traction for the early identification of kidney damage. In this prospective observational study, 57 patients with acute kidney disease and 23 patients without acute renal damage were consecutively enrolled; urinary concentrations of NGAL, LFABP, CYR61, TIMP-2, IGFBP-7, and [TIMP-2 X IGFBP-7], and serum concentrations of PENK and KIM-1 were obtained in all patients. The primary endpoint was to assess the role of serum and urinary markers in distinguishing prerenal from renal pathogenesis of AKI. The secondary endpoint was to evaluate the possible association between urinary and serum concentrations of these markers and the severity of acute kidney injury. Urinary TIMP-2, NGAL, and IGFBP-7 concentrations were higher in patients with AKI compared with the control group, with statistical significance. Among patients with AKI, we found higher concentrations of LFABP, Cyr61, TIMP-2, NGAL, IGFBP-7, and [TIMP-2]x[IGFBP-7] according to AKI aetiology, with statistical significance maintained in multivariable logistic regression for IGFBP-7. The ROC curve confirmed that IGFBP-7 has a predictive role in the aetiological diagnosis of AKI. A significant association between urinary LFABP and TIMP-2 and serum KIM-1 concentrations (p = 0.0001) and the variation in creatinine values from baseline to enrollment was found. Furthermore, we found a statistically significant correlation between KIM-1 and the variation in creatinine levels from admission to discharge. This study highlights an association between the concentrations of the novel biomarkers and the aetiology of AKI, with a possible role for these molecules in stratifying patients with acute renal disease.