What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

The treatment of metabolic acidosis should focus on addressing the underlying cause while providing supportive care, with sodium bicarbonate therapy reserved for severe cases (pH <7.2) rather than being used routinely for all forms of metabolic acidosis. 1, 2

Diagnosis and Assessment

• Define metabolic acidosis as blood pH below 7.35, corresponding to hydrogen ion concentration >45 nmol/L 1
• Calculate anion gap: [Na+] - ([Cl-] + [HCO3-]), normal range 8-12 mEq/L 1
• Classify severity based on total CO2 level:
  • Mild: ≥19 mmol/L
  • Moderate to Severe: <19 mmol/L 1
• Initial laboratory testing should include:
  • Arterial blood gases
  • Complete metabolic panel
  • Serum ketones
  • Serum lactate
  • Serum osmolality
  • Urinalysis 1

Treatment Algorithm

Step 1: Address the Underlying Cause

• Treat the primary condition causing acidosis:
  • Insulin for diabetic ketoacidosis 1
  • Restore blood volume in shock 2
  • Hemodialysis for severe renal failure 1
  • Discontinue causative medications or treat intoxications 2

Step 2: Fluid Resuscitation

• Administer isotonic saline at 15-20 mL/kg/hr initially for all causes of metabolic acidosis 1
• Avoid excessive use of 0.9% saline which can cause iatrogenic hyperchloremic acidosis 1

Step 3: Sodium Bicarbonate Therapy

• Do not use sodium bicarbonate to treat metabolic acidosis arising from tissue hypoperfusion 3
• Consider sodium bicarbonate only for:
  • Severe acidosis (pH <7.2) 1, 2
  • Cardiac arrest: 1-2 vials (44.6-100 mEq) initially, then 50 mL (44.6-50 mEq) every 5-10 minutes as needed 2
  • Drug intoxications (barbiturates, salicylates, methanol) 2
  • Severe renal tubular acidosis 2

Step 4: Dosing for Non-Emergent Metabolic Acidosis

• For less urgent forms: 2-5 mEq/kg body weight over 4-8 hours 2
• Avoid full correction of low total CO2 content during first 24 hours to prevent rebound alkalosis 2
• Target total CO2 content of about 20 mEq/L at end of first day 2

Step 5: Renal Replacement Therapy

• Consider hemodialysis for:
  • Severe acidosis with renal failure 1
  • Toxic alcohol levels ≥50 mg/dL 1
  • Anion gap >27 mmol/L 1

Special Considerations

Lactic Acidosis

• Focus on improving tissue oxygenation rather than bicarbonate administration 4
• Treatment with sodium bicarbonate has failed to reduce morbidity and mortality despite improvement in acid-base parameters 4

Chronic Kidney Disease

• Correct acidosis with sodium bicarbonate to prevent:
  • Bone demineralization
  • Muscle protein degradation
  • Hormonal abnormalities 5, 6

Recent Evidence

• A recent target trial emulation (2025) suggests bicarbonate administration may be associated with a small but statistically significant reduction in mortality (1.9% absolute reduction) for ICU patients with metabolic acidosis 7

Monitoring

• Serial arterial or venous blood gases to assess response to treatment 1
• Monitor serum bicarbonate levels regularly 1
• Assess vital signs, mental status, signs of dehydration, and evidence of shock 1

Pitfalls to Avoid

• Overly rapid correction of acidosis can lead to:
  • Rebound alkalosis
  • Undesired hypernatremia
  • Hypocalcemia
  • Hypokalemia 2
• Sodium bicarbonate administration may worsen intracellular acidosis in some cases 8
• Avoid achieving total CO2 content above normal within first day of therapy 2

By following this structured approach to treating metabolic acidosis, clinicians can effectively manage this condition while minimizing potential complications from treatment.