CST3 and acute kidney injury: As presented in Table 3 the serum level of cystatin C in children with AKI admitted to the pediatric intensive care unit (SMD = 1.50; 95% CI: 1.02-1.99; p < 0.001) and the ones who developed AKI following cardiac surgery (SMD = 0.71; 95% CI: 0.41-1.02; p < 0.001) was significantly higher than non-AKI children while in other settings (including sepsis, cancer, Low Birth Weight Infants, Contrast induced nephropathy, Contrast induced nephropathy and Asphyxia) no significant difference was observed between AKI and non-AKI children (SMD = 1.09; 95% CI: -1.15-3.33; p = 0.34).