How is metabolic alkalosis treated?

Treatment of Metabolic Alkalosis

The treatment of metabolic alkalosis depends on identifying and correcting the underlying cause, with potassium-sparing diuretics (particularly amiloride) as first-line pharmacologic therapy, followed by acetazolamide in appropriate patients, and aggressive electrolyte repletion with potassium chloride and sodium chloride as needed. 1

Initial Assessment and Diagnosis

Before initiating treatment, determine the etiology by assessing:

• Volume status (hypovolemic vs. euvolemic) and measure urinary chloride to distinguish chloride-responsive (<20 mEq/L) from chloride-resistant (>20 mEq/L) alkalosis 1, 2
• Serum potassium and chloride levels, as hypokalemia and hypochloremia are common perpetuating factors 1, 2
• Medication history, particularly diuretic use (loop and thiazide diuretics are frequent culprits) 1
• Plasma renin and aldosterone levels if hyperaldosteronism is suspected 2

Treatment Algorithm

Step 1: Address the Underlying Cause

• Discontinue or reduce diuretic doses if clinically feasible 1
• Stop nasogastric suctioning or treat refractory vomiting if present 3
• Avoid NSAIDs and sodium-rich medications that may interfere with treatment 4

Step 2: Electrolyte Repletion (Cornerstone of Therapy)

Potassium chloride supplementation is essential:

• Administer 20-60 mEq/day to maintain serum potassium in the 4.5-5.0 mEq/L range 1
• Use only potassium chloride, not potassium citrate or other salts, as these can worsen metabolic alkalosis 1
• In vomiting-induced chloride depletion, potassium chloride infusion restores renal bicarbonate excretion 2

Sodium chloride supplementation:

• For chloride-responsive alkalosis with volume depletion, administer sodium chloride (5-10 mmol/kg/day) 1

Step 3: Pharmacologic Interventions

First-line: Potassium-sparing diuretics

• Amiloride is the most effective potassium-sparing diuretic for metabolic alkalosis 1

  • Initial dose: 2.5 mg daily, titrate up to 5 mg daily 1
  • Provides improvement in edema/hypertension while countering hypokalemia and metabolic alkalosis 1

• Spironolactone is an alternative aldosterone antagonist 1

  • Initial dose: 25 mg daily, titrate up to 50-100 mg daily 1
  • Particularly useful in heart failure patients and cirrhotic ascites 4, 5
  • Side effects include gynaecomastia, decreased libido, and impotence in men 4

Second-line: Acetazolamide

• Acetazolamide is useful in patients with heart failure and diuretic-induced alkalosis with adequate kidney function 1, 5
• Mechanism: Inhibits carbonic anhydrase, causing renal loss of bicarbonate with sodium, water, and potassium 6
• Promotes urinary alkalinization and diuresis 6

Step 4: Severe or Refractory Cases

For severe metabolic alkalosis requiring rapid correction:

Mineral acid administration:

• Ammonium chloride is the primary drug of choice for rapid correction 7
• Dilute hydrochloric acid (0.1-0.2 N) via central venous catheter for patients with hepatic or severe renal dysfunction 7, 3
• Hemodialysis with low-bicarbonate/high-chloride dialysate is the treatment of choice in refractory cases with concurrent renal failure 1, 3

Special Populations

Heart failure patients:

• Appropriate management of circulatory failure is integral 5
• Add an aldosterone antagonist (spironolactone) to the diuretic regimen 5
• Consider switching to longer-acting loop diuretics 1

Cirrhotic patients with ascites:

• High-dose loop diuretics (frusemide >160 mg/day) are associated with severe electrolyte disturbance and metabolic alkalosis 4
• Use cautiously with careful biochemical monitoring 4

Bartter or Gitelman syndrome:

• Consider in patients with chloride-resistant metabolic alkalosis (urinary Cl >20 mEq/L) 1
• Treat with sodium chloride and potassium chloride supplementation 1
• NSAIDs may reduce prostaglandin-mediated salt wasting 1
• Use gastric acid inhibitors together with NSAIDs 1

Critical Pitfalls to Avoid

• Never use sodium bicarbonate or alkalinization strategies—these are contraindicated and will worsen the alkalosis 1
• Avoid combining potassium-sparing diuretics with ACE inhibitors without close monitoring due to hyperkalemia risk 1
• Do not use potassium-sparing diuretics in patients with significant renal dysfunction or existing hyperkalemia 1
• Avoid potassium salts other than potassium chloride (such as potassium citrate), which worsen metabolic alkalosis 1
• Monitor for over-diuresis, which causes intravascular volume depletion leading to renal impairment, hepatic encephalopathy, and hyponatraemia 4

Monitoring Requirements

• Serial monitoring of serum electrolytes, acid-base status, and volume status is crucial 1
• Adjust therapy based on clinical response and laboratory parameters 1
• Measure urinary sodium excretion to assess compliance with sodium restriction if applicable 4