The three most common equations for estimating GFR include the bedside Schwartz equation based on Creatinine (40), Cystatin-C based equation (41), Creatinine-Cystatin C-based Chronic Kidney Disease in Children (CKiD) equation (42), and U25 modification for CKiD equation for patients under 25 years old (43). Here, CST3 is linked to chronic kidney disease.