The clinical application of Schwartz formula has been validated in many studies using either iohexol or Cystatin-C or inulin based clearance.6,13-15 Stanely et al. compared the Schwartz with measured Ccr and found similar results of GFR estimation and recommended that Schwartz formula can be used for routine screening children for CKD.4 This evidence concerns the gene CST3 and chronic kidney disease.