Background It has been argued that the benefits of reducing sodium loading may be offset by increased activation of the renin-angiotensin-aldosterone system (RAAS) and sympathetic nervous system.This study aimed to investigate the long-term effects of an increase in dialysis sodium removal on circulating RAAS and sympathetic system in hypertensive hemodialysis (HD) patients with normal post-HD volume status.Methods Thirty hypertensive HD patients were enrolled in this pilot trial.After one month period of dialysis with standard dialysate sodium of 138 mmol/L,the patients were followed up for a four months period with dialysate sodium set at 136 mmol/L,without changes in instructions regarding dietary sodium control.During the period of study,the dry weight was adjusted monthly under the guidance of bioimpedance spectroscopy to maintain post-HD volume status in a steady state; 44-hour ambulatory blood pressure,plasma renin,angiotensin Ⅱ (Ang Ⅱ),aldosterone,and norepinephrine (NE) were measured.Results After four months of HD with low dialysate sodium of 136 mmol/L,44-hour systolic and diastolic blood pressures (BPs) were significantly lower (-10 and-6 mmHg),in the absence of changes in antihypertensive medications.No significant changes were observed in plasma renin,Ang Ⅱ,aldosterone,and NE concentrations.The post-HD volume parameters were kept constant.Conclusion Mildly increasing dialysis sodium removal over 4 months can significantly improve BP control and does not activate circulating RAAS and sympathetic nervous system in hypertensive HD patients.