Chronic kidney disease (CKD) and end-stage renal disease are highly prevalent in Taiwan. Cardiovascular disease (CVD) is the most common cause of death in children with CKD. Nitric oxide (NO) deficiency links CKD and CVD. Asymmetric dimethylarginine (ADMA), a NO synthase inhibitor, its level is increased in kidney disease and cardiovascular disease and serves as a methylation biomarker.