Table 1.

Biomarkers of AKI

AKI biomarker	Characteristics/functions	AUCs for AKI prediction	Settings (sample collection)	Limitations
NGAL	A 25-kDa protein of the family of lipocalins with bacteriostatic function	0.87	All hospitalized patients [24]	May be elevated in the settings of sepsis, CKD and UTI [25]
		0.72	Cardiac surgery [26]	The lack of specific cut-off values [27]
		0.80	ICU [28]
KIM-1	A 38.7-kDa type I transmembrane glycoprotein	0.85	Cardiac surgery [18]	May be elevated in the settings of chronic proteinuria and inflammatory diseases [16]
		0.77	ICU and others [18]	High cost and poor availability [27]
L-FABP	A 14-kDa protein from the large superfamily of lipid binding proteins	0.81	Cardiac surgery [21]	Strongly associated with anemia in nondiabetic patients
IL-18	A 24-kDa cytokine from the IL-1 family of cytokines	0.72	Cardiac surgery in adults [26]	No certain prediction of AKI in adults [16]
		0.75	ICU [29]
[TIMP-2]X[IGFBP7]	TIMP-2: a 21-kDa protein, endogenous inhibitor of meralloproteinase activities	0.80	ICU [22]	May be elevated in the setting of diabetes
	IGFBP7: a 29-kDa secreted protein known to bind to and inhibit signaling through IGF-1 receptors			Needs validation to define clinical role [31]
		0.84	Cardiac surgery [30]
uAGT	A 453-amino acid-long protein with 10 N-terminal amino acids	0.84	Acute decompensated heart failure [32]	Needs validation in other clinical settings. May be considered as a prognostic biomarker. Data for use as a diagnostic biomarker are limited [33]
		0.70	Cardiac surgery patients [34]
		0.73	Other etiologies of AKI [23]

L-FABP, liver-type fatty acid-binding protein; TIMP-2, tissue inhibitor of metalloproteinase-2; IGFBP7, IGF binding protein 7; ICU, intensive care unit; UTI, urinary tract infection; AUC, area under the curve. Modified from Kashani et al. [33]