What is the recommended treatment for bicarbonate (bicarb) supplementation in patients with chronic kidney disease (CKD)?

Bicarbonate Supplementation in Chronic Kidney Disease

In patients with chronic kidney disease (CKD) and serum bicarbonate concentrations <22 mmol/L, oral bicarbonate supplementation should be given to maintain serum bicarbonate within the normal range (24-26 mmol/L) to slow progression of kidney disease and improve clinical outcomes. 1, 2

Indications for Bicarbonate Therapy in CKD

• Oral bicarbonate supplementation is recommended when serum bicarbonate levels fall below 22 mmol/L in CKD patients 1
• Treatment aims to maintain serum bicarbonate levels in the normal range of 24-26 mmol/L 1
• Metabolic acidosis typically develops when GFR falls below approximately 25 mL/min/1.73 m² due to impaired tubular bicarbonate production 3

Dosing Recommendations

• For most CKD patients: 2-4 g/day or 25-50 mEq/day of oral sodium bicarbonate is typically effective 2
• Dosing should be adjusted based on regular monitoring of serum bicarbonate levels 2
• For patients unable to tolerate commercial preparations, baking soda (1/4 teaspoon = 1 g of sodium bicarbonate) may be substituted 1

Benefits of Correcting Metabolic Acidosis in CKD

• Slows progression of kidney disease 4, 5
• Reduces protein degradation and improves albumin synthesis 2, 6
• Decreases risk of major adverse cardiovascular events (MACE) 5
• Improves nutritional status with increases in serum protein and albumin levels 7
• Reduces mortality in CKD patients 4, 5
• Improves bone metabolism by reducing bone resorption 1, 6

Alternative Approaches

• Increasing fruit and vegetable intake can also reduce net acid production (NEAP) and is recommended for CKD stages 1-4 1
• A diet rich in fruits and vegetables may provide additional benefits beyond bicarbonate supplementation, including:
  • Reduction in systolic blood pressure 1
  • Potential weight loss benefits 1
  • Increased fiber intake, which may reduce inflammation 1

Monitoring Recommendations

• Measure serum bicarbonate regularly after initiation of therapy 2
• Monitor for potential adverse effects:
  • Worsening hypertension due to sodium load 2
  • Fluid retention 2
  • Electrolyte disturbances, particularly potassium 2
• Ensure serum bicarbonate does not exceed the upper limit of normal to avoid metabolic alkalosis 1, 2

Special Considerations

• Use with caution in patients with heart failure or hypertension due to the additional sodium load 2
• Consider the patient's volume status before initiating therapy 2
• In patients with CKD and nephrotic-range proteinuria, vitamin D supplementation may also be considered alongside bicarbonate therapy 1

Evidence Quality and Recommendations

The recommendation for bicarbonate supplementation in CKD patients with serum bicarbonate <22 mmol/L is supported by multiple guidelines, including the 2024 KDIGO Clinical Practice Guideline 1, the 2020 KDOQI Clinical Practice Guideline 1, and the 2015 Canadian Society of Nephrology Commentary 1. Recent research further supports this recommendation, with studies showing reduced mortality, decreased MACE, and slower CKD progression with bicarbonate supplementation 4, 5.

While the evidence is strong for the benefits of correcting metabolic acidosis in CKD, clinicians should be vigilant about potential adverse effects related to sodium load and carefully monitor patients after initiating therapy.