The BASE Study: Bicarbonate Administration to Stabilize Estimated Glomerular Filtration Rate (eGFR)

Inclusion criteria

• Serum bicarbonate 20-28 mEq/L at screening (the average of the two most recent values in Baseline must be 20-28 mEq/L prior to randomization)
• Moderate to severe chronic kidney disease (CKD) at the time of screening, defined as one of the following:

• eGFR 20-44 ml/min/1.73m2 or
• eGFR 45-59 ml/min/1.73m2 plus random urinary albumin:creatinine (ACR) ≥100 mg/gm
• Blood pressure <160/100 mm Hg at screening (must be <150/100 mm Hg prior to randomization)
• Lean body weight 38.0-96.0 kg at the time of screening
• Age allowing legal consent without parental involvement (18-21 years, depending on individual state regulations)
• Able to provide consent
• Able to travel to study visits
• Able to read English
• In the opinion of the site investigator, willing and able to follow the study treatment regimen and comply with the site investigator's recommendations
• In the opinion of the site investigator, medically stable

Exclusion criteria

• Use of chronic daily oral alkali (such as sodium bicarbonate, sodium citrate, potassium citrate, etc) with one exception: calcium carbonate ≤1500 mg/day is allowed, as some will take this for the indication of bone health
• On five or more antihypertensive and/or diuretic agents, regardless of the indication
• Serum potassium <3.3 or ≥5.5 mEq/L at screening (must be 3.5-5.5 mEq/L prior to randomization)
• Self-reported vegetarian
• New York Heart Association Class 3 or 4 heart failure symptoms, known left ventricular ejection fraction ≤30%, or hospital admission for heart failure within the past 3 months
• Frequent urinary tract infections (≥2 in the past year)
• Presence of indwelling urinary catheter or urinary conduit (such as neobladder or urostomy)
• Factors judged to limit adherence to interventions (e.g., alcoholism, history of missing clinic visits, chronic gastrointestinal disorder that makes compliance with the intervention unreliable)
• Organ transplant recipients (excluding cornea)
• Active glomerular disease requiring or potentially requiring immunosuppressive treatment
• Chronic immunosuppressive therapy (for ≥3 months) for any indication. This does not include oral steroids <10 mg per day, inhaled steroids, or topical steroids
• Anticipated initiation of dialysis or kidney transplantation within 12 months as assessed by the site investigator
• Current participation in another interventional research study
• Malignancy requiring therapy within 2 years (basal or squamous cell skin carcinoma and localized prostate cancer are exempted)
• Pregnancy or planning to become pregnant or currently breast-feeding. Women of childbearing potential (pre-menopausal and not surgically sterilized) will have urine pregnancy test before enrollment.
• Life expectancy <12 months as determined by the site investigator
• Institutionalized individuals, including prisoners and nursing home residents
• Plans to leave the immediate area within the next 12 months
• Routinely leaves town for multiple weeks each year such that protocol visits would be missed
• Chronic use of supplemental oxygen
• Use of both angiotensin-converting-enzyme inhibitor (ACEI) and Angiotensin II Receptor Blockers (ARBs)