What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

The primary treatment for metabolic acidosis should focus on addressing the underlying cause while providing supportive care, with sodium bicarbonate therapy reserved for severe cases (pH < 7.2) or specific clinical scenarios. 1, 2

Diagnostic Assessment

• Immediate laboratory evaluation should include:

  • Arterial blood gases
  • Complete metabolic panel
  • Serum ketones and lactate
  • Anion gap calculation ([Na+] - ([Cl-] + [HCO3-])) with normal range 8-12 mEq/L
  • Urinalysis 1

• Calculate anion gap to differentiate between:

  • High anion gap metabolic acidosis (>12 mEq/L): lactic acidosis, ketoacidosis, renal failure, toxin ingestion
  • Normal anion gap (hyperchloremic) acidosis: GI bicarbonate loss, renal tubular acidosis, early renal failure 1, 3

Treatment Algorithm

Step 1: Address the Underlying Cause

• Diabetes: Insulin administration 4
• Shock or dehydration: Fluid resuscitation with isotonic saline (15-20 mL/kg/hr initially) 1, 2
• Lactic acidosis: Improve tissue oxygenation and perfusion 5
• Toxin ingestion: Specific antidotes or removal procedures 2
• Renal failure: Dialysis if indicated 6

Step 2: Supportive Care

• Fluid resuscitation to restore intravascular volume and renal perfusion
  • In absence of cardiac compromise, isotonic saline (0.9% NaCl) at 15-20 mL/kg/hr during first hour
  • Subsequent fluid choice depends on hydration status and electrolytes 4
• Electrolyte monitoring and replacement, particularly potassium
  • Once renal function is assured, include 20-30 mEq/L potassium in infusions 4

Step 3: Bicarbonate Therapy

For Severe Acidosis (pH < 7.2):

• IV sodium bicarbonate may be considered 1, 2
• In cardiac arrest: 44.6-100 mEq (1-2 vials of 50 mL) initially, then 44.6-50 mEq every 5-10 minutes as needed based on arterial pH monitoring 2
• In less urgent forms: 2-5 mEq/kg body weight over 4-8 hours 2

For Chronic Metabolic Acidosis:

• Oral bicarbonate therapy to maintain serum bicarbonate ≥ 22 mmol/L
• Typical dose: 2-4 g/day (25-50 mEq/day) divided into 2-3 doses 1
• Dietary modifications: Increase fruit and vegetable consumption as alternative alkali source 1

Important Considerations and Cautions

• DO NOT use sodium bicarbonate to treat metabolic acidosis arising from tissue hypoperfusion (such as in sepsis) as per intensive care guidelines 4
• Avoid rapid correction of chronic acidosis as this may lead to paradoxical CNS acidosis and other complications 2, 3
• Monitor for potential complications of bicarbonate therapy:
  • Hypernatremia
  • Volume overload
  • Paradoxical intracellular acidosis
  • Hypocalcemia
  • Hypokalemia 2, 3
• Aim for partial correction initially (total CO2 content of about 20 mEq/L in first 24 hours) rather than complete normalization 2
• Serial monitoring of acid-base status is crucial to guide therapy and avoid overcorrection 1

Special Populations

Diabetic Ketoacidosis:

• Initial treatment with subcutaneous or intravenous insulin to correct hyperglycemia and metabolic derangement
• Once acidosis resolves, initiate metformin while continuing insulin therapy 4

Chronic Kidney Disease:

• Protein restriction and sodium bicarbonate supplements for predialysis patients
• Adjustment of dialysate alkalinity for patients on dialysis 6

Metabolic acidosis increases protein degradation and can lead to muscle wasting if left untreated, making appropriate management essential for preventing long-term complications 6, 3.