The pathogenesis of IDH is unclear. A number of factors have been implicated and probably work synergistically to promote the rise in BP. These include: subclinical volume overload, activation of the sympathetic and renin-angiotensin-aldosterone systems, endothelial dysfunction, sodium gain during dialysis, use of erythropoietin stimulating agents (ESAs) and removal of anti-hypertensive agents during dialysis.