What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

The treatment of metabolic acidosis should primarily focus on addressing the underlying cause while providing supportive care, with bicarbonate therapy reserved for severe cases (pH <7.2) at a dose of 1-2 mEq/kg over 1 hour. 1

Initial Assessment and Classification

First, determine the type and severity of metabolic acidosis:

• 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

Essential laboratory tests include:

• Arterial blood gases
• Complete metabolic panel
• Serum ketones and lactate
• Serum osmolality
• Urinalysis 1

Treatment Algorithm

1. Fluid Resuscitation

• Begin with isotonic saline at 15-20 mL/kg/hr for all causes of metabolic acidosis 1
• Ensure adequate volume status and tissue perfusion

2. Address Underlying Cause

• Diabetic ketoacidosis: Insulin therapy plus fluid resuscitation 2, 1
  • For ketoacidosis/ketosis: Initiate subcutaneous or intravenous insulin to rapidly correct hyperglycemia and metabolic derangement 2
  • Once acidosis resolves, initiate metformin while continuing subcutaneous insulin 2
• Lactic acidosis: Improve tissue oxygenation and treat shock 1, 3
• Toxic alcohol ingestion: Fomepizole or ethanol and hemodialysis 1
• Renal failure: Dialysis for severe cases 1

3. Bicarbonate Therapy

Bicarbonate therapy is indicated in:

• Severe acidosis (pH <7.2) 1
• Cardiac arrest: 1-2 vials (44.6-100 mEq) initially, then 44.6-50 mEq every 5-10 minutes as needed 4
• Less urgent metabolic acidosis: 2-5 mEq/kg over 4-8 hours 4

Important cautions with bicarbonate therapy:

• Avoid rapid correction of total CO2 within the first 24 hours to prevent rebound alkalosis 4
• Target initial total CO2 content of about 20 mEq/L at the end of the first day 4
• Monitor for hypernatremia, especially with rapid infusion 4

4. Renal Replacement Therapy

Consider hemodialysis for:

• Severe acidosis unresponsive to medical management
• Renal failure
• Toxic alcohol levels ≥50 mg/dL 1
• Anion gap >27 mmol/L (strongly consider) or 23-27 mmol/L (consider) 1

Special Considerations

Chronic Kidney Disease

• Correct serum bicarbonate to ≥22 mmol/L with alkali replacement therapy 1
• Consider dietary modifications:
  • Increase fruit and vegetable consumption as alternative alkali sources 1
  • Protein intake of 0.8 g/kg body weight per day 1
  • Restrict sodium to <2,300 mg/day 1

Monitoring Response

• Serial arterial or venous blood gases to assess treatment response 1
• Monitor vital signs, mental status, and signs of dehydration 1
• For chronic conditions, monthly monitoring of serum bicarbonate levels 1

Recent Evidence on Outcomes

A recent target trial emulation (2025) found that sodium bicarbonate administration was associated with a small but statistically significant reduction in mortality (1.9% absolute reduction) for ICU patients with metabolic acidosis 5. This benefit was observed across multiple subgroups, including patients with acute kidney injury and those requiring vasoactive therapy.

Potential Complications of Untreated Metabolic Acidosis

Failure to treat metabolic acidosis can lead to:

• Impaired cardiovascular function
• Cardiac arrhythmias
• Inflammation and suppressed immune response 6
• Protein catabolism and muscle wasting 7, 8
• Hormonal abnormalities affecting growth hormone, insulin, and thyroid function 7
• Bone demineralization 7

Remember that the primary goal in treating metabolic acidosis is to identify and correct the underlying cause while providing appropriate supportive care to minimize complications.