How is metabolic acidosis treated?

Treatment of Metabolic Acidosis

Treatment of metabolic acidosis must be directed at the underlying cause first, with sodium bicarbonate therapy reserved for specific indications based on severity and etiology. 1, 2

Diagnostic Framework Before Treatment

Determine the anion gap to guide treatment approach, as this distinguishes between acid accumulation versus bicarbonate loss. 3, 4

• High anion gap acidosis indicates acid accumulation (lactic acidosis, ketoacidosis, renal failure, toxins) 4, 5
• Normal anion gap acidosis indicates bicarbonate loss (diarrhea, renal tubular acidosis) or chloride salt ingestion 5, 1

Measure arterial blood gas to assess pH and PaCO2 for complete acid-base assessment, particularly in complex cases. 1

Treatment Algorithm by Etiology

Diabetic Ketoacidosis (DKA)

Focus on insulin therapy and fluid resuscitation as primary treatment, NOT bicarbonate. 2, 1

• Continuous intravenous insulin is the standard of care for critically ill and mentally obtunded patients 2
• Restoration of circulatory volume and tissue perfusion is the primary goal 2
• Bicarbonate therapy is NOT indicated unless pH falls below 6.9-7.0 1, 2
• Bicarbonate administration has not been shown to improve resolution of acidosis or time to discharge in DKA 2
• Monitor arterial or venous blood gases to assess treatment response 1
• Administer basal insulin 2-4 hours before stopping IV insulin to prevent rebound ketoacidosis 2

Chronic Kidney Disease (CKD)

Maintain serum bicarbonate ≥22 mmol/L to prevent bone disease, protein catabolism, and CKD progression. 1, 2

Treatment thresholds:

• Bicarbonate ≥22 mmol/L: Monitor without pharmacological intervention 1
• Bicarbonate 18-22 mmol/L: Consider oral alkali supplementation with or without dietary intervention 1
• Bicarbonate <18 mmol/L: Initiate pharmacological treatment with oral sodium bicarbonate 1, 2

Oral sodium bicarbonate dosing: 0.5-1.0 mEq/kg/day (typically 2-4 g/day or 25-50 mEq/day) divided into 2-3 doses 1, 2

Monitoring requirements:

• Measure serum bicarbonate monthly initially, then at least every 3-4 months once stable 1
• Monitor blood pressure, serum potassium, and fluid status regularly 1
• Ensure treatment doesn't cause hypertension or hyperkalemia 1

Dietary approach: Increase fruit and vegetable intake to raise serum bicarbonate and potentially decrease systolic blood pressure and body weight 1

Critical caveat: Avoid citrate-containing alkali salts in CKD patients exposed to aluminum, as they increase aluminum absorption 1, 2

Severe Malaria in Children

Metabolic acidosis with respiratory distress indicates compensated shock requiring volume resuscitation. 6

• Administer 20 ml/kg bolus of colloid or 0.9% saline 6
• In children with coma, use 20 ml/kg of 4.5% albumin as the preferred resuscitation fluid 6
• Metabolic acidosis resolves with correction of hypovolemia and treatment of anemia by adequate blood transfusion 2
• No evidence supports sodium bicarbonate use in severe malaria 2

Septic Shock and Tissue Hypoperfusion

Sodium bicarbonate should NOT be used to treat metabolic acidosis from tissue hypoperfusion in sepsis. 2

• Focus treatment on restoring tissue perfusion with fluid resuscitation and vasopressors 2
• The effectiveness of sodium bicarbonate in septic shock is unsure, and acidosis may have protective effects 2

Indications for Intravenous Sodium Bicarbonate

FDA-approved indications for IV sodium bicarbonate include: 7

• Severe renal disease with metabolic acidosis 7
• Uncontrolled diabetes (when pH <6.9-7.0) 7
• Circulatory insufficiency due to shock or severe dehydration 7
• Cardiac arrest 7
• Severe primary lactic acidosis 7
• Drug intoxications (barbiturates, salicylates, methyl alcohol) 7
• Hemolytic reactions requiring urine alkalinization 7
• Severe diarrhea with significant bicarbonate loss 7

Vigorous bicarbonate therapy is required when rapid increase in plasma CO2 content is crucial (cardiac arrest, circulatory insufficiency, severe lactic acidosis). 7

Hospitalization Criteria

Admit patients with: 1

• Severe metabolic acidosis (bicarbonate <18 mmol/L) requiring pharmacological treatment and close monitoring 1
• Acute illness or catabolic state (critical illness, major surgery, acute kidney injury on CKD) 1
• Symptomatic complications (protein wasting, severe muscle weakness, altered mental status, inability to maintain oral intake) 1
• Severe electrolyte disturbances (hyperkalemia, severe hypocalcemia) 1
• Need for kidney replacement therapy initiation 1

Outpatient management is appropriate for: 1

• Stable CKD patients with bicarbonate 18-22 mmol/L on oral alkali supplementation 1
• Patients without intercurrent illness who can maintain adequate oral intake 1

Critical Monitoring and Pitfalls

Monitor potassium closely as acidosis causes transcellular shift of potassium leading to hyperkalemia, which corrects with acidosis treatment. 2, 3

Common pitfalls to avoid:

• Do NOT use furosemide unless hypervolemia, hyperkalemia, or renal acidosis are present 2
• Do NOT use dopamine to improve renal function 2
• Do NOT use hypotonic fluids (glucose solutions) for fluid resuscitation 2
• Do NOT reduce protein intake in catabolic CKD patients, as this worsens nitrogen balance without delaying dialysis 1
• Monitor for "overshoot" alkalosis when administering sodium bicarbonate 3
• Be cautious with sodium bicarbonate in advanced heart failure with volume overload, severe uncontrolled hypertension, or significant edema 1

Special Populations

Pediatric patients: Treat milder acidosis (bicarbonate >18 mmol/L) more aggressively to optimize growth and bone health, as chronic metabolic acidosis causes growth retardation. 1, 2

Dialysis patients: Maintain serum bicarbonate ≥22 mmol/L and monitor monthly. 2 Consider bicarbonate-based dialysate buffer in patients with lactic acidosis or liver failure. 2

Malignant hyperthermia: Manage acidosis primarily through hyperventilation, with sodium bicarbonate administered at a low threshold as low pH is associated with poor outcomes. 1