CST3 and chronic kidney disease: We have also strong discrepancies between CKD prevalence using either CKD-EPI or the cystatine C-based equations (in our population, prevalence of stage 3 CKD with the Levey cystatin C-based equations (GFR = 76.7 × CC (mg/L) -1.19) is as low as 1.1%, data not detailed).