What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

The treatment of metabolic acidosis should focus on addressing the underlying cause while maintaining serum bicarbonate levels above 22 mmol/L to prevent complications related to bone metabolism, muscle catabolism, and other systemic effects. 1, 2

Diagnostic Approach

• Determine the cause of metabolic acidosis by calculating the anion gap [(Na+ + K+) - (Cl- + HCO3-)] to differentiate between high anion gap and normal anion gap acidosis 3
• Monitor serum bicarbonate levels monthly in maintenance dialysis patients and regularly in patients with chronic kidney disease (CKD) 1
• Assess electrolytes, particularly potassium levels, as acidosis can cause hyperkalemia due to transcellular shift of potassium 2

Treatment Based on Etiology

Chronic Kidney Disease-Associated Acidosis

• Treat when serum bicarbonate is consistently < 18 mmol/L to prevent bone and muscle metabolism abnormalities 1, 2
• Administer oral sodium bicarbonate (2-4 g/day or 25-50 mEq/day) to effectively increase serum bicarbonate concentrations 1
• Maintain serum bicarbonate at or above 22 mmol/L in maintenance dialysis patients 1
• Avoid citrate alkali salts in CKD patients exposed to aluminum salts as they may increase aluminum absorption 4

Diabetic Ketoacidosis

• Focus on insulin therapy, fluid resuscitation, and electrolyte replacement rather than bicarbonate therapy 1, 2
• Provide continuous intravenous insulin as the standard of care for critically ill and mentally obtunded patients 1
• Restore circulatory volume and tissue perfusion as primary goals 1
• Note that bicarbonate administration has not been shown to improve resolution of acidosis or time to discharge in diabetic ketoacidosis 1, 2

Severe Acute Metabolic Acidosis

• For severe acidosis (pH < 7.2), particularly in cardiac arrest, administer sodium bicarbonate intravenously 5, 3
• In cardiac arrest, a rapid intravenous dose of one to two 50 mL vials (44.6 to 100 mEq) may be given initially and continued at a rate of 50 mL every 5-10 minutes if necessary 5
• For less urgent forms of metabolic acidosis, administer approximately 2-5 mEq/kg of body weight over a 4-8 hour period, depending on the severity 5
• Monitor treatment by measuring blood gases, plasma osmolarity, arterial blood lactate, hemodynamics, and cardiac rhythm 5

Special Considerations

Potential Complications of Bicarbonate Therapy

• Bicarbonate administration may worsen intracellular acidosis, reduce ionized calcium, and produce hyperosmolality 1, 2
• Avoid rapid infusion of large quantities of bicarbonate as it can produce an undesirable rise in plasma sodium concentration 5
• Do not attempt full correction of a low total CO2 content during the first 24 hours to avoid unrecognized alkalosis 5
• Target a total CO2 content of about 20 mEq/liter at the end of the first day of therapy, which will usually be associated with a normal blood pH 5

Monitoring During Treatment

• Monitor plasma potassium closely during treatment of acid-base disturbances, as changes in pH may be accompanied by alterations in plasma potassium concentrations 3
• Plan bicarbonate therapy in a stepwise fashion since the degree of response from a given dose is not precisely predictable 5
• Modify treatment based on clinical response and laboratory values 5

Long-term Management

• Correction of metabolic acidosis has been associated with increased serum albumin, decreased protein degradation rates, and increased plasma concentrations of branched chain amino acids in patients with CKD 1
• Treatment of metabolic acidosis can improve bone histology and ameliorate excess protein catabolism 4
• In children with renal tubular acidosis, normalization of serum bicarbonate is one component of the return of normal growth parameters 4