Objective: The aim of this study was to verify the estimation and the predictive abilities of serum creatinine (Cr), serum cystatin C (Cys C), and related formulas for acute kidney injury (AKI).
Patients and methods: Thirty patients who underwent cadaveric donor liver transplantation were enrolled in this prospective study. Glomerular filtration rate (GFR) was assessed by the 99mTc DTPA clearance method and estimated by Cr-predicted clearances (Cockcroft-Gault method [CG] and abbreviated Modification of Diet in Renal Disease equation [MDRD]) as well as by 3 other Cys C-based formulas (Hoek, Filler, and Larsson). AKI was confirmed as GFR<80 mL/min/1.73 m2 in the first posttransplantation week.
Results: GFR was significantly correlated with reciprocal Cr, reciprocal Cys C, and the 5 formulas (P<.001 for all). The receiver operating characteristic (ROC) area of Cys C was larger than that of Cr (.937 vs .794, P<.05). ROC area of Hoek, or Filler or Larsson was also larger than that of CG or MDRD (.937, .935, .937 vs .802, .849, P<.05 for all). ROC analysis showed the cutoff values were 1.0 mg/dL for Cr and 1.57 mg/L for Cys C. Hoek, Filler, and Larsson equations all underestimated AKI; their optimal cutoff values should be adjusted to 47, 56, and 44 mL/min/1.73 m2, respectively.
Conclusion: Cys C is a better predictor of AKI than Cr. A value of more than 1.57 mg/L might be considered a new definition of AKI.