LCN2 and acute kidney injury: AKI = acute kidney injury; FGF23 = fibroblast growth factor 23; uIL18 = urine interleukin 18; uNGAL = urine neutrophil gelatinase-associated lipocalin; uKIM1 = urine kidney injury molecule-1; uLFABP = urine liver-type fatty acid-binding protein.