What is the treatment for metabolic alkalosis?

Treatment of Metabolic Alkalosis

Identify and Correct the Underlying Cause

The cornerstone of treating metabolic alkalosis is identifying whether it is saline-responsive (chloride-responsive) or saline-resistant, then correcting volume depletion, chloride depletion, and potassium deficits accordingly. 1

Determine the Type of Metabolic Alkalosis

• Measure urinary chloride concentration to distinguish between saline-responsive and saline-resistant alkalosis 2, 1

  • Urinary chloride <20 mEq/L indicates saline-responsive alkalosis (typically from vomiting, nasogastric suction, or diuretic use after the diuretic effect has worn off) 2
  • Urinary chloride >20 mEq/L indicates saline-resistant alkalosis (typically from ongoing diuretic therapy, hyperaldosteronism, or severe hypokalemia) 2

• Assess volume status clinically to guide fluid replacement strategy 1

First-Line Treatment: Fluid and Electrolyte Repletion

For saline-responsive metabolic alkalosis (the most common type), administer isotonic saline (0.9% NaCl) to restore volume and chloride, which allows the kidneys to excrete excess bicarbonate. 1

• Infuse potassium chloride (KCl) aggressively, as this is particularly effective in vomiting-induced chloride depletion alkalosis and restores the kidney's ability to excrete bicarbonate 1

  • Use potassium chloride specifically, not potassium citrate or other potassium salts, as these worsen alkalosis 3
  • Hypokalemia is nearly universal in metabolic alkalosis and must be corrected 1

• Correct chloride depletion as this is essential for the kidneys to excrete bicarbonate; without adequate chloride, the kidneys cannot eliminate excess bicarbonate even with volume repletion 1, 4

Treatment for Saline-Resistant Alkalosis

For saline-resistant metabolic alkalosis, address the underlying hormonal abnormalities rather than giving saline, which will not correct the alkalosis and may worsen volume overload. 2

• In congestive heart failure patients, use aldosterone antagonists (spironolactone or eplerenone) as part of the diuretic regimen to prevent ongoing bicarbonate retention 4

• Optimize management of the underlying disease (heart failure, hyperaldosteronism) as neurohormonal activation perpetuates the alkalosis 4

Pharmacologic Interventions When Conservative Measures Fail

Acetazolamide for Moderate-Severe Alkalosis

When fluid and electrolyte correction alone does not fully resolve metabolic alkalosis, administer acetazolamide 500 mg intravenously to enhance renal bicarbonate excretion. 5, 4

• Acetazolamide acts rapidly (within 2 hours) with maximal effect at approximately 15.5 hours and sustained action for 48 hours 5
• Mean bicarbonate reduction is 6.4 mmol/L at 24 hours, with normalization of base excess and pH 5
• This is particularly useful in critically ill ventilated patients and those with heart failure where fluid administration is limited 5, 4
• Ensure fluid and electrolyte abnormalities are corrected first before administering acetazolamide 5

Mineral Acid Administration for Severe, Life-Threatening Alkalosis

When metabolic alkalosis requires rapid resolution or when the patient cannot tolerate fluid and electrolyte therapy, administer mineral acids intravenously. 6

• First choice: Ammonium chloride IV for patients with normal hepatic and renal function 6

• For patients with hepatic dysfunction or severe renal dysfunction, use dilute hydrochloric acid (0.1-0.2 N) via central venous catheter as both ammonium chloride and arginine monohydrochloride require hepatic conversion for activity 6

• Calculate the acid deficit and administer cautiously with frequent monitoring 6

Alternative Therapies

• Low-bicarbonate dialysis should be considered in patients with metabolic alkalosis accompanied by kidney failure 4

• Acetazolamide may have limited efficacy in severe renal impairment as it requires adequate renal function to promote bicarbonate excretion 4

Critical Monitoring During Treatment

• Monitor arterial pH, serum bicarbonate, and electrolytes (particularly potassium and chloride) every 2-4 hours during active treatment 3

• Assess volume status continuously to avoid over-resuscitation in patients with heart failure or renal dysfunction 4

• Watch for complications including hypokalemia (which can worsen during correction), volume overload, and rebound acidosis with overly aggressive acid administration 6

Common Pitfalls to Avoid

• Never use potassium citrate or other non-chloride potassium salts, as these aggravate metabolic alkalosis rather than correct it 3

• Do not give saline to saline-resistant alkalosis (high urinary chloride), as this worsens volume overload without correcting the alkalosis 2

• Avoid administering acetazolamide before correcting volume and electrolyte deficits, as this reduces its effectiveness and may worsen hypokalemia 5

• Do not use mineral acids as first-line therapy; reserve these for severe cases unresponsive to conservative management or when rapid correction is essential 6

• In heart failure patients, recognize that diuretic-induced alkalosis requires aldosterone antagonists, not just potassium and chloride repletion 4