Table 1.

Serum creatinine, biomarkers, and its relationship between different AKI scenarios

AKI Scenarios	Serum Creatinine	Biomarker	Example
Kidney stress	✔	✔	Cr: identifies patients with mild CKD who are most at risk for developing AKI
			Biom: revealed when at risk of AKI
Subclinical AKI	×	✔	Cr: after the insult it takes up to 48 h to rise
			Biom: some rises in the first hours
AKI diagnosis	✔	×	Cr: the diagnosis of AKI by KDIGO is made by an increase in serum creatinine and a decrease in urinary output
			Biom: the ADQI group proposes to add biomarkers to the classification, not yet incorporated into KDIGO guideline
Prediction of severe AKI (2,3)	×	✔	Cr: does not identify which patient progressed to severe AKI
			Biom: Nephrochek >0.3 and NGAL >450 ng/ml predicts AKI severity
Start KRT	×	×	Cr: does not identify which patient should start KRT
			Biom: does not identify which patient should start KRT
Stop KRT	×	×	Cr: does not identify when to stop KRT
			Biom: does not identify when to stop KRT
Acute tubular necrosis	×	×	Cr: does not differentiate ATN from other etiologies
			Biom: does not differentiate ATN from other etiologies
Acute interstitial nephritis	×	✔	Cr: does not differentiate ATN from other etiologies
			Biom: high values of TNF-α and IL-9 may identify AIN
Contrast-associated nephropathy	✔	✔	Cr: increases 12 h after contrast application
			Biom: Cystatin C rises earlier and is more sensitive than creatinine
Sepsis-associated AKI	×	✔	Cr: reduced production of creatinine during sepsis
			Biom: NGAL could have better performance identifying AKI than creatinine
Proximal tubular damage	×	✔	Cr: does not identify proximal tubular damage
			Biom: Cystatin C, IL-18, NGAL, L-FABP, could identify proximal tubular damage
Kidney function improvement after AKI	×	✔	Cr: does not identify renal repair or improvement
			Biom: KIM-1, NGAL, and NephroCheck have been shown to be associated with kidney improvement or repair
AKD or CKD progression from AKI	✔	✔	Cr: creatinine values have been associated with progression to AKD and CKD
			Biom: KIM-1, Ang, NGAL, and NephroCheck have been associated with progression to CKD
Guide therapy	×	×	Cr: its values do not guide management or treatment
			Biom: there is still not enough evidence to guide management or treatment due to its elevation
Availability	✔	×	Cr: universal availability and wide acceptance by health personnel
			Biom: not available in many places, low acceptance by health personnel
Cost	✔	×	Cr: cheap and affordable
			Biom: expensive

ADQI, Acute Disease Quality Initiative; AIN, acute interstitial nephritis; AKI, acute kidney injury; AKD, acute kidney disease; Ang, angiotensin; ATN, acute tubular necrosis; Biom, biomarker; Cr, creatinine; KIM-1, kidney injury molecule 1; L-FABP, liver-type fatty acid–binding protein; NGAL, neutrophil gelatinase-associated lipocalin; KRT, kidney replacement therapy.