What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

The treatment of metabolic acidosis should target the underlying cause while maintaining serum bicarbonate levels above 22 mmol/L to prevent bone and muscle metabolism abnormalities. 1, 2

Etiology-Based Treatment Approach

Chronic Kidney Disease (CKD)-Associated Acidosis

• Treat when serum bicarbonate is consistently < 18 mmol/L to prevent bone and muscle metabolism abnormalities 1, 2
• Oral sodium bicarbonate (2-4 g/day or 25-50 mEq/day) can effectively increase serum bicarbonate concentrations 1
• Maintain serum bicarbonate at or above 22 mmol/L in maintenance dialysis patients 1
• Correction of acidemia has been associated with increased serum albumin, decreased protein degradation rates, and improved plasma concentrations of branched chain amino acids 1
• Citrate alkali salts should be avoided in CKD patients exposed to aluminum salts as they may increase aluminum absorption 3

Diabetic Ketoacidosis

• Focus on insulin therapy, fluid resuscitation, and electrolyte replacement rather than bicarbonate therapy 1, 2
• Continuous intravenous insulin is the standard of care for critically ill and mentally obtunded patients 1
• Restoration of circulatory volume and tissue perfusion is a primary goal 1
• Bicarbonate administration has not been shown to improve resolution of acidosis or time to discharge 1, 2

Severe Acidosis (pH < 7.2)

• In cardiac arrest or severe acidosis, intravenous sodium bicarbonate may be administered rapidly 4
• Initial dose: one to two 50 mL vials (44.6 to 100 mEq) followed by 50 mL (44.6 to 50 mEq) every 5-10 minutes if necessary 4
• For less urgent forms of metabolic acidosis, administer 2-5 mEq/kg of body weight over 4-8 hours 4
• Monitor treatment by measuring blood gases, plasma osmolarity, arterial blood lactate, hemodynamics, and cardiac rhythm 4

Monitoring and Precautions

• Monitor serum electrolytes, particularly potassium levels, as acidosis can cause hyperkalemia due to transcellular shift of potassium 1, 2
• Avoid rapid full correction of low total CO2 content during the first 24 hours to prevent unrecognized alkalosis 4
• Target total CO2 content of about 20 mEq/liter at the end of the first day of therapy 4
• Be aware that bicarbonate administration may worsen intracellular acidosis, reduce ionized calcium, and produce hyperosmolality 1, 2
• Calculate the anion gap [(Na+ + K+) - (Cl- + HCO3-)] to help diagnose the cause of metabolic acidosis and guide treatment 5

Special Considerations

• In children with renal tubular acidosis, normalization of serum bicarbonate is important for normal growth parameters 3
• In patients with chronic metabolic acidosis, correction of acidosis can improve bone histology and reduce excess protein catabolism 3
• Treatment of metabolic acidosis should be planned in a stepwise fashion since the degree of response from a given dose is not precisely predictable 4
• Long-term untreated metabolic acidosis can lead to dysfunction of multiple systems and organs, as well as CKD progression 6
• Newer treatments such as veverimer (which binds hydrogen ions in the intestines) are being studied for metabolic acidosis in CKD patients 6

Treatment Algorithm

1. Identify and treat the underlying cause of metabolic acidosis 5, 7
2. Assess severity based on pH, bicarbonate levels, and clinical presentation 8
3. For severe acidosis (pH < 7.2): Consider IV sodium bicarbonate 4
4. For CKD-associated acidosis: Use oral sodium bicarbonate when serum bicarbonate < 18 mmol/L 1, 2
5. For diabetic ketoacidosis: Prioritize insulin, fluids, and electrolyte replacement 1
6. Monitor response with serial measurements of pH, bicarbonate, and electrolytes 4, 8
7. Adjust treatment based on clinical response and laboratory parameters 4