How do you correct metabolic acidosis?

How to Correct Metabolic Acidosis

The correction of metabolic acidosis depends fundamentally on treating the underlying cause, with sodium bicarbonate therapy reserved for specific clinical scenarios—primarily chronic kidney disease with bicarbonate <18-22 mmol/L, severe diabetic ketoacidosis with pH <6.9-7.0, and hyperkalemia. 1, 2

Initial Diagnostic Assessment

Before initiating treatment, establish the type and severity of metabolic acidosis:

• Measure serum bicarbonate, arterial blood gas (pH, PaCO2), anion gap, and serum electrolytes to characterize the acidosis and guide treatment 1, 3
• Calculate the anion gap [(Na+ + K+) - (Cl- + HCO3-)] to differentiate between high anion gap acidosis (lactic acidosis, ketoacidosis, renal failure, toxins) and normal anion gap acidosis (bicarbonate loss, renal tubular acidosis) 4, 5
• Assess for precipitating causes including sepsis, diabetic ketoacidosis, renal failure, drug ingestions, and gastrointestinal bicarbonate losses 3, 5

Treatment Algorithm Based on Clinical Context

1. Sepsis-Related Metabolic Acidosis

DO NOT use sodium bicarbonate to treat metabolic acidosis arising from tissue hypoperfusion in sepsis. 2

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

2. Diabetic Ketoacidosis (DKA)

Bicarbonate therapy is generally NOT indicated in DKA unless pH falls below 6.9-7.0. 2, 1

• Primary treatment is insulin therapy and fluid resuscitation, which corrects the underlying ketoacidosis 2
• For patients with marked hyperglycemia (≥250 mg/dL, A1C ≥8.5%) without acidosis, initiate long-acting insulin while starting metformin 2
• For patients with ketosis/ketoacidosis, use subcutaneous or intravenous insulin to rapidly correct hyperglycemia and metabolic derangement 2
• Once acidosis resolves, transition to subcutaneous insulin with metformin 2
• Monitor arterial or venous blood gases to assess treatment response 2

3. Chronic Kidney Disease (CKD)

For CKD patients, oral sodium bicarbonate is the first-line pharmacological treatment when serum bicarbonate falls below 22 mmol/L, with strong indication for treatment when <18 mmol/L. 1

Treatment Thresholds:

• Bicarbonate ≥22 mmol/L: Monitor monthly 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

Dosing and Administration:

• Start oral sodium bicarbonate at 0.5-1.0 mEq/kg/day divided into 2-3 doses 1
• Target serum bicarbonate ≥22 mmol/L to prevent protein catabolism, bone disease, and CKD progression 1
• Sodium bicarbonate does not significantly increase blood pressure or body weight when used appropriately 1

Monitoring Parameters:

• Monitor serum bicarbonate monthly initially, then at least every 4 months once stable 1
• Check blood pressure, serum potassium, and fluid status regularly to ensure treatment doesn't cause hypertension or hyperkalemia 1
• Monitor for signs of volume overload, particularly in patients with heart failure 1

Dietary Approach:

• Increase fruit and vegetable intake to provide potassium citrate salts that generate alkali and help buffer acids 1
• This approach may also decrease systolic blood pressure and body weight compared to sodium bicarbonate alone 1
• Reduce animal protein intake (which produces sulfur-containing amino acids that generate nonvolatile acids) 1

Important Caveats:

• Avoid citrate-containing alkali in CKD patients exposed to aluminum salts, as citrate increases aluminum absorption and worsens bone disease 1
• Use caution or avoid sodium bicarbonate in patients with advanced heart failure with volume overload, severe uncontrolled hypertension, or significant edema 1
• In pediatric CKD patients, consider treating milder acidosis (bicarbonate >18 mmol/L) more aggressively to optimize growth and bone health 1

4. Acute Severe Metabolic Acidosis

For severe metabolic acidosis with pH <7.2 or bicarbonate <18 mmol/L in acute settings, sodium bicarbonate IV may be indicated. 6, 4

• Sodium bicarbonate IV is FDA-approved for correction of metabolic acidosis and systemic alkalinization 6
• Tromethamine IV is an alternative for prevention and correction of metabolic acidosis, particularly during cardiac bypass surgery, cardiac arrest, or when sodium load is contraindicated 7
• Monitor blood pH and gases closely to avoid "overshoot" alkalosis 4
• Monitor plasma potassium closely during treatment, as changes in pH alter potassium concentrations 4

5. Hyperkalemia with Metabolic Acidosis

Sodium bicarbonate is specifically indicated for metabolic acidosis associated with hyperkalemia. 8

• Alkalinizing therapy helps shift potassium intracellularly 8
• Combine with other hyperkalemia treatments as clinically indicated 8

Indications for Hospitalization vs. Outpatient Management

Hospitalize if:

• Bicarbonate <18 mmol/L requiring pharmacological treatment and close monitoring 1
• Acute illness or catabolic state (critical illness, major surgery, acute kidney injury) 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

Manage as outpatient if:

• Bicarbonate 18-22 mmol/L in stable CKD patients with oral alkali supplementation 1
• No intercurrent illness and adequate oral intake 1

Common Pitfalls to Avoid

• Do NOT use bicarbonate empirically in septic shock—treat the underlying hypoperfusion instead 2
• Do NOT use bicarbonate routinely in DKA—insulin and fluids are the primary treatment 2, 1
• Do NOT reduce protein intake in hospitalized CKD patients with acute illness, as the catabolic state requires increased protein intake 1
• Do NOT ignore the sodium load from sodium bicarbonate in patients with heart failure or hypertension 1
• Do NOT use citrate-containing preparations in CKD patients exposed to aluminum 1
• Do NOT treat the bicarbonate number alone—always address the underlying cause of acidosis 2, 8