What is the treatment for metabolic alkalosis?

Treatment of Metabolic Alkalosis

The first-line treatment for metabolic alkalosis is isotonic saline (0.9% NaCl) administration to correct volume depletion and chloride deficit, which promotes renal bicarbonate excretion and suppresses the renin-angiotensin-aldosterone system. 1

Diagnostic Assessment

Before initiating treatment, identify the underlying cause:

• Laboratory findings:

  • Elevated serum bicarbonate (>26 mEq/L)
  • Decreased serum chloride (<98 mmol/L)
  • Often decreased serum potassium (<3.5 mEq/L)
  • Elevated arterial pH (>7.45)
  • Urinary chloride levels: elevated in diuretic-induced cases, low (<20 mEq/L) in volume depletion 1

• Common causes:

  • Contraction alkalosis (volume depletion)
  • Diuretic therapy (especially loop and thiazide diuretics)
  • Vomiting or nasogastric suction
  • Mineralocorticoid excess
  • Bartter syndrome

Treatment Algorithm

1. Volume Repletion

• For mild-moderate cases:

  • Isotonic saline (0.9% NaCl) administration 1
  • Oral rehydration for mild cases
  • IV, nasogastric, or subcutaneous administration for moderate-severe cases

• For severe cases with renal failure:

  • Consider hemodialysis with normal bicarbonate dialysate (25-28 mmol/L) 2, 3

2. Electrolyte Correction

• Potassium chloride supplementation:

  • Target potassium level: 4.0-5.0 mEq/L 1
  • For severe hypokalemia with symptoms or ECG changes: potassium chloride 0.25 mmol/kg over 30 minutes
  • Maximum rate: 20 mEq/hour via peripheral vein with ECG monitoring 1

• Magnesium replacement:

  • Check and correct magnesium levels if deficient, as hypomagnesemia can perpetuate hypokalemia 1

3. Address Underlying Cause

• For diuretic-induced alkalosis:

  • Reduce dose or discontinue the offending diuretic 1
  • Consider adding potassium-sparing diuretics if appropriate

• For vomiting or nasogastric suction:

  • Reduce or eliminate gastric drainage when possible
  • Consider H₂ blockers or proton pump inhibitors to reduce gastric acid production 3

• For Bartter syndrome:

  • Long-term potassium chloride supplementation
  • Consider NSAIDs in symptomatic patients 1

4. Pharmacological Interventions for Refractory Cases

• Acetazolamide:

  • Enhances renal bicarbonate excretion 2
  • Particularly useful in heart failure patients with metabolic alkalosis

• Mineral acids (for severe, life-threatening cases):

  • Ammonium chloride (first choice if liver function normal)
  • Hydrochloric acid (0.1-0.2 N) via central venous catheter for patients with hepatic dysfunction 4

Monitoring

• Check serum electrolytes (potassium, sodium, chloride, bicarbonate) within 24 hours of initiating therapy 1
• More frequent monitoring for IV replacement
• Monitor ECG during rapid potassium correction
• Adjust fluid and electrolyte therapy based on renal function

Important Cautions

• Avoid:

  • Correcting potassium too rapidly
  • Using potassium supplements with potassium-sparing diuretics without close monitoring
  • Using non-chloride potassium salts when hypochloremia is present 1
  • Potassium-sparing diuretics in volume-depleted patients
  • Thiazide diuretics, which may worsen hypovolemia 1

• Special considerations for heart failure patients:

  • Appropriate management of circulatory failure
  • Consider aldosterone antagonists in the diuretic regimen 2

By systematically addressing volume status, electrolyte imbalances, and the underlying cause, most cases of metabolic alkalosis can be effectively treated. Severe cases may require more aggressive interventions, but the cornerstone of therapy remains chloride repletion and volume correction.