CST3 and acute kidney injury: Bland–Altman analysis of both cystatin C and MDRD formula, used to estimate GFR at 48 h prior to the development of AKI, indicated that the cystatin C-based formula was most accurate with a mean difference (bias) of −2 (−40 to +35) mL/min/1.73 m2 compared to iohexol GFR.