The health care burden of CKD is substantial and growing with 10-15% of the population affected in both developed and developing countries. It is well established that CKD is associated with systemic inflammation, which promotes cardiovascular disease and body wasting. However, causal therapies to treat systemic inflammation, and treat its adverse consequences remain sparse. As kidney function declines in all forms of CKD, oxalate levels increase in the plasma, leading to increased systemic exposure to oxalate and consequent tissue injury. Work from the investigators has shown that elevated plasma oxalate levels activate the NLRP3 inflammasome which in turn leads to the processing and release of cytokines. The investigators seek to test the hypothesis that oxalate contributes to the systemic inflammation observed in patients with end-stage renal disease (ESRD). The investigators plan to define the association between plasma oxalate levels and signs of systemic inflammation in patients on hemodialysis. In a second step the investigators will examine whether hemodiafiltration lowers plasma oxalate more efficiently than hemodialysis and reduces signs of systemic inflammation. Confirmation of the hypothesis may lead to the identification of oxalate as a novel therapeutic target for interventional trials aimed at reducing plasma oxalate in patients with ESRD.