07/27/2017 Unable to contact research team to confirm reason for withdrawing study.

This is a non randomized crossover trial investigating whether changing the pattern of bicarbonate administration during hemodialysis will result in the more efficient filtration of highly protein bound solutes. The experimental group will be dialyzed with low bicarbonate dialysate for the first half of dialysis then switched over to normal bicarbonate dialysate for the second half. The control group will be dialyzed entirely with normal bicarbonate dialysate. The two groups will switch one week late and patients will serve as their own matched controls for a completely standard dialysis and one that is split into two halves with different bicarbonate concentrations.

Investigators will try to perform dialysis with a low bicarbonate bath which will leave patients blood pH (Hydrogen ion concentration) relatively unchanged then switch to a normal bicarbonate bath during the second half of dialysis so that they attain the pH (Hydrogen ion concentration) they normally would. Investigators will use these measurements to test test the hypothesis that Indoxyl Sulfate (IS) binds to proteins with greater affinity under basic conditions and further to test the hypothesis that it is possible to remove a greater amount of Indoxyl Sulfate (IS) when patients are maintained relatively acidotic during dialysis for a longer period of time due to the greater availability of free IS that can pass through the dialyzer.

Inclusion Criteria:

• Chronic Stable Dialysis for at least 6 months

Exclusion Criteria:

• Patients with serum potassium concentration below 4.0 mEq/L on previous monthly lab test or corrected serum calcium below 8.5 mEq/L
• Hospitalization within the past 12 months
• Adults unable to consent
• Children
• Pregnant women
• Prisoners