Do we give sodium bicarbonate (NaHCO3) for chronic kidney disease (CKD)?

Sodium Bicarbonate for Chronic Kidney Disease

Yes, sodium bicarbonate (NaHCO3) should be given to CKD patients when serum bicarbonate falls below 22 mmol/L to slow kidney disease progression, reduce mortality, and prevent complications of metabolic acidosis. 1, 2

When to Initiate Bicarbonate Therapy

Target threshold: Start oral sodium bicarbonate when serum bicarbonate is <22 mmol/L in CKD patients stages 3-5. 1, 2

• The 2024 KDIGO guidelines recommend pharmacological treatment to prevent development of acidosis with potential clinical implications, particularly when serum bicarbonate falls below 18 mmol/L. 1
• Monthly monitoring of serum bicarbonate is recommended in CKD patients to identify those requiring intervention. 2
• Treatment aims to maintain serum bicarbonate in the normal range of 24-26 mmol/L, but should not exceed the upper limit of normal to avoid metabolic alkalosis. 1, 2

Dosing Recommendations

Standard dosing: 2-4 g/day (25-50 mEq/day) of oral sodium bicarbonate is typically effective to normalize serum bicarbonate levels. 2

• For patients unable to tolerate commercial preparations, baking soda (1/4 teaspoon = 1 g of sodium bicarbonate) may be substituted. 2
• Dose should be titrated based on serum bicarbonate response, checking levels within 2-4 weeks of initiation or dose adjustment. 2

Clinical Benefits Supported by Evidence

Kidney protection: The most recent high-quality trial (UBI Study, 2019) demonstrated that sodium bicarbonate treatment significantly reduced creatinine doubling (6.6% vs 17.0%, p<0.001) and delayed dialysis initiation (6.9% vs 12.3%, p=0.016) over 36 months in CKD stages 3-5. 3

Mortality reduction: The same trial showed reduced all-cause mortality (3.1% vs 6.8%, p=0.004) with sodium bicarbonate treatment. 3 A large observational study of 25,599 CKD stage V patients confirmed significantly lower mortality risk (HR 0.75,95% CI 0.74-0.77) in sodium bicarbonate users. 4

Cardiovascular benefits: Sodium bicarbonate use was associated with lower rates of major adverse cardiovascular events (HR 0.95% CI 0.92-0.98) and hospitalizations for acute pulmonary edema (HR 0.92,95% CI 0.88-0.96). 4

Metabolic improvements: Correction of acidosis prevents protein degradation, improves albumin synthesis, reduces bone resorption, and in children prevents growth retardation. 2, 5

Critical Monitoring Requirements

Monitor for adverse effects:

• Serum bicarbonate monthly to ensure levels remain ≥22 mmol/L but do not exceed upper limit of normal. 1, 2
• Blood pressure, as sodium loading can worsen hypertension (though recent data suggest the effect is modest). 6, 7
• Serum potassium, particularly in patients on RAS inhibitors, as bicarbonate therapy can help manage hyperkalemia. 1
• Fluid status and body weight to detect volume overload. 2

Important Caveats and Contraindications

Sodium load considerations: While the UBI Study found no significant effect on blood pressure or hospitalizations with mean doses of 1.09-1.13 mmol/kg/day, 3 and the SoBic trial showed no significant increase in 24-hour ambulatory blood pressure over 8 weeks, 6 animal studies demonstrate that NaHCO3 loading can promote hypertension and volume retention in CKD. 7

Balance risk versus benefit: The sodium load must be weighed against benefits, particularly in patients with:

• Advanced heart failure (avoid in decompensated states). 2
• Poorly controlled hypertension requiring close monitoring. 2
• Significant volume overload. 2

Do not use in: Patients with sodium-wasting nephropathy require different management and should not receive routine sodium restriction or supplementation. 1

Alternative Approaches

Dietary modification: Increasing fruit and vegetable intake reduces net acid production and may provide additional benefits beyond bicarbonate supplementation, including reduced systolic blood pressure, potential weight loss, and increased fiber intake. 2, 5

Avoid citrate-containing alkali: In CKD patients exposed to aluminum salts, citrate can increase aluminum absorption and worsen bone disease. 5

Special Populations

Hyperkalemia management: For CKD patients developing hyperkalemia on RAS inhibitors, sodium bicarbonate can be used as part of a strategy to control potassium levels while maintaining RAS blockade. 1

Pediatric CKD: Metabolic acidosis should be corrected to serum bicarbonate ≥22 mEq/L in children with CKD, as correction is essential before considering growth hormone therapy. 2

Dialysis patients: Use of bicarbonate-based dialysis solutions helps maintain target bicarbonate levels in addition to or instead of oral supplementation. 2

Common Pitfalls to Avoid

• Do not wait until bicarbonate is severely depressed (<18 mmol/L) before initiating therapy; start at <22 mmol/L to prevent complications. 1, 2
• Do not over-correct bicarbonate above the upper limit of normal, as this causes metabolic alkalosis. 1
• Do not ignore the sodium load in patients with heart failure or uncontrolled hypertension; monitor blood pressure and volume status closely. 2, 7
• Do not assume bicarbonate therapy is only for acidosis; emerging evidence suggests benefits may extend beyond pH correction. 8