Cardiovascular disease (CVD) is the leading cause of death in patients with chronic kidney disease (CKD) and large artery damage is a major factor that contributes to death. Metabolic acidosis is a common complication of CKD resulting from an inability of the diseased kidney to excrete the daily dietary acid load and it is associated with all-cause mortality in patients with CKD. However, the effect of treatment of metabolic acidosis with oral sodium bicarbonate on endothelial dysfunction and arterial stiffness in patients with CKD has not been evaluated. The investigators propose a prospective, randomized, controlled, open-label 14-week crossover pilot study examining the effect of treatment of metabolic acidosis with oral sodium bicarbonate on vascular endothelial function in 20 patients with CKD stage IV with metabolic acidosis.

Inclusion Criteria

• Age 40-70 years
• CKD stage IV (eGFR 15-29 ml/min/1.73m2; stable renal function in the past 3 months)
• Serum bicarbonate level of < 20 and ≥ 16 meq/L (at least 2 consecutive weekly measurements)
• Body mass index < 40 kg/m2 (FMD measurements can be inaccurate in severely obese patients)
• Ability to give informed consent
• Stable anti-hypertensive, diabetic and lipid lowering regimen for at least one month prior to randomization

Exclusion Criteria:

• Significant comorbid conditions that lead the investigator to conclude that life expectancy is less than 1 year
• Uncontrolled hypertension
• Expected to undergo living related kidney transplant in next 6 months
• Expected to start dialysis in next 3 months
• Overt congestive heart failure
• Use of sevelamer
• Use of calcium carbonate