In addition, timing of AKI definition (p = 0.11), AKI definition criteria (p = 0.11), sample size of study (p = 0.34), storage degree (p = 0.26) and setting of study (p = 0.21) did not affect the difference in urine cystatin C levels between AKI and non-AKI children. This evidence concerns the gene CST3 and acute kidney injury.