The study is a cross-sectional analysis of all patients on hemodialysis patients treated at Tungs' Taichung Metroharbor hospital(500 patients). Patients ≥20 years of age and been on maintenance hemodialysis for at least 3 month before the study. The dialysis sessions were 3.5 to 4.5 h three times per week, with a blood flow greater than 300 mL/min, a dialysate flow of 600 mL/min, and a bicarbonate buffer.