Table 4.

Estimation of unknown baseline serum creatinine

Estimating baseline sCr method	Characteristics in the diagnosis of AKI	References
An estimated sCr determined by back-calculation using MDRD assuming a GFR of 75 ml/min/1.73 m2	Low specificity especially in CKD patients	[18–24]
An estimated sCr determined by back-calculation using MDRD assuming a GFR of 100 ml/min/1.73 m2	Very high sensitivity and very low specificity	[23]
The first admission sCr	Low sensitivity	[22]
A minimum inpatient sCr during the first 7 days	Low specificity	[22]
A minimum sCr during the first 7 days in the ICU	Low specificity although tendency to underestimate the AKI stage	[23]
An estimated sCr using multiple imputation methods such as sex, race, comorbidity (CKD, etc), and a minimum inpatient sCr	High specificity	[19]
A minimum inpatient sCr		[11]
sCr = 1.0 mg/dl (male)/0.8 mg/dl (female)		[25]

sCr serum creatinine, GFR glomerular filtration rate, CKD chronic kidney disease