How do you manage metabolic alkalosis?

Management of Metabolic Alkalosis

The management of metabolic alkalosis should focus on identifying and treating the underlying cause, correcting volume and electrolyte abnormalities, and using specific pharmacologic interventions when necessary. 1, 2

Diagnosis and Assessment

• Metabolic alkalosis is characterized by elevated serum bicarbonate and arterial pH above 7.45 2
• Assess for common causes:
  • Vomiting or nasogastric suction (loss of gastric acid)
  • Diuretic therapy (especially loop and thiazide diuretics)
  • Hypokalemia and hypochloremia
  • Mineralocorticoid excess
  • Bartter's and Gitelman's syndromes 2, 3
• Measure urinary chloride to distinguish between:
  • Saline-responsive alkalosis (urinary chloride <10 mEq/L)
  • Saline-resistant alkalosis (urinary chloride >20 mEq/L) 4

Initial Management

• Address the underlying cause (e.g., discontinue offending medications, treat vomiting) 2
• Correct volume depletion with isotonic saline (0.9% NaCl) in saline-responsive cases 3, 4
• Replete potassium and chloride deficiencies 5
• Discontinue or reduce doses of diuretics if possible 1

Pharmacologic Interventions

First-line: Chloride and Volume Repletion

• For volume-depleted patients: administer isotonic saline to restore effective arterial blood volume 5, 3
• For hypokalemic patients: administer potassium chloride supplements to correct hypokalemia 2

Second-line: Carbonic Anhydrase Inhibitors

• Acetazolamide (250-500 mg orally or intravenously every 6-12 hours) enhances renal bicarbonate excretion 6, 5
• Acetazolamide is particularly useful in patients with:
  • Heart failure with diuretic-induced alkalosis
  • Adequate kidney function
  • Adequate volume status 6, 5
• Caution: may worsen hypokalemia and volume depletion 6

Third-line: Acid Administration

• For severe, refractory cases (pH >7.60 or with significant symptoms):
  • Ammonium chloride (NH4Cl) infusion (first choice in patients with normal liver function) 7
  • Dilute hydrochloric acid (0.1-0.2 N HCl) via central venous catheter for patients with hepatic dysfunction 7

Special Situations

Heart Failure with Metabolic Alkalosis

• Optimize heart failure treatment to improve cardiac output 5
• Consider adding an aldosterone antagonist (spironolactone) to the diuretic regimen 1, 5
• Acetazolamide can be particularly effective in heart failure patients with diuretic-induced alkalosis 5

Bartter Syndrome

• Treat with potassium and chloride supplements 1
• NSAIDs (indomethacin, ibuprofen) to reduce prostaglandin-mediated salt wasting 1
• K-sparing diuretics, ACE inhibitors, or ARBs may be considered in individual cases with severe electrolyte abnormalities, but use caution as they may worsen salt wasting 1

Diuretic-Induced Alkalosis

• Consider switching to longer-acting loop diuretics (bumetanide or torsemide) if using furosemide 1
• Add a potassium-sparing diuretic like spironolactone to counter hypokalemia and metabolic alkalosis 1
• Acetazolamide may be helpful for metabolic alkalosis associated with diuretic use 1

Monitoring and Follow-up

• Monitor serum electrolytes (potassium, sodium, chloride, bicarbonate)
• Monitor acid-base status (arterial pH, pCO2)
• Monitor volume status and hemodynamics
• Adjust therapy based on clinical response and laboratory parameters 2, 3

Cautions and Pitfalls

• Avoid overly rapid correction of chronic metabolic alkalosis
• Be cautious with saline administration in patients with heart failure or renal failure 5
• Acetazolamide can worsen hypokalemia; ensure adequate potassium replacement 6
• Hydrochloric acid administration carries risks of hemolysis, tissue necrosis, and overcorrection; use only in severe cases under close monitoring 7
• In Bartter syndrome, avoid thiazides as they may lead to life-threatening hypovolemia 1