What to do for metabolic alkalosis?

Management of Metabolic Alkalosis

The primary treatment for metabolic alkalosis is chloride replacement with sodium chloride and potassium chloride supplementation, while discontinuing or reducing diuretics if possible. 1

Initial Assessment and Diagnosis

Evaluate the following key parameters to guide management:

• Measure urinary chloride to distinguish chloride-responsive (urinary Cl <20 mEq/L) from chloride-resistant alkalosis (urinary Cl >20 mEq/L) 2
• Check serum electrolytes including potassium, sodium, and chloride levels 2, 1
• Assess volume status to determine if the patient is volume depleted or volume overloaded 2
• Identify the underlying cause: most commonly diuretic therapy (especially loop and thiazide diuretics), vomiting, or nasogastric suction 2, 1, 3

Treatment Algorithm

Step 1: Address the Underlying Cause

• Discontinue or reduce diuretic doses if clinically feasible 2, 1
• Stop gastric acid losses if vomiting or nasogastric suction is present 3

Step 2: Chloride and Potassium Replacement

• Administer sodium chloride (intravenous or oral) for volume-depleted patients with chloride-responsive alkalosis 1, 3
• Provide potassium chloride supplementation at doses of 20-60 mEq/day, targeting serum potassium levels of 4.5-5.0 mEq/L 2, 1
• Avoid non-chloride potassium salts (such as potassium citrate or potassium bicarbonate) as these will worsen the alkalosis 2, 1

Step 3: Add Potassium-Sparing Diuretics (If Diuretics Cannot Be Stopped)

Amiloride is the first-line potassium-sparing diuretic for correcting metabolic alkalosis 2:

• Start with amiloride 2.5 mg daily, titrate up to 5 mg daily as needed 2
• Amiloride provides dual benefit by improving edema/hypertension while countering hypokalemia and metabolic alkalosis 2

Alternative option:

• Spironolactone 25 mg daily, titrate up to 50-100 mg daily 2
• Particularly useful in heart failure patients with diuretic-induced alkalosis 2, 4

Step 4: Consider Acetazolamide for Refractory Cases

• Acetazolamide can be used in patients with heart failure and diuretic-induced alkalosis who have adequate kidney function 2, 4
• Acetazolamide inhibits carbonic anhydrase, causing renal loss of bicarbonate and promoting diuresis 5
• Caution: Increasing doses may not increase diuresis and can worsen side effects; acetazolamide may precipitate acidosis in patients with pulmonary obstruction or emphysema 6

Special Situations

Severe or Refractory Metabolic Alkalosis

• Avoid sodium bicarbonate or alkalinization strategies as these are contraindicated and will worsen the alkalosis 2
• Hemodialysis with low-bicarbonate/high-chloride dialysate is the treatment of choice for refractory cases, especially with concurrent renal failure 2
• Dilute hydrochloric acid (0.1-0.2 N HCl) may be infused via central venous catheter in severe cases, though this carries risk of hemolysis 7, 8

Bartter or Gitelman Syndrome

If chloride-resistant alkalosis with urinary Cl >20 mEq/L is present, consider these rare tubulopathies 2:

• Sodium chloride supplementation at 5-10 mmol/kg/day 2
• NSAIDs for symptomatic patients to reduce prostaglandin-mediated salt wasting 2
• Gastric acid inhibitors should be used together with NSAIDs 2
• Genetic testing for definitive diagnosis if suspected 2

Heart Failure Patients

• Add aldosterone antagonist (spironolactone) to the diuretic regimen 2
• Consider switching from furosemide to torsemide for more consistent bioavailability 4
• Sequential nephron blockade with thiazide-type diuretics (metolazone 2.5-10 mg daily) may enhance decongestion while reducing loop diuretic dose 4

Critical Monitoring Parameters

• Monitor serum electrolytes (potassium, sodium, chloride) regularly 2, 1
• Track acid-base status with arterial blood gases or venous bicarbonate 2
• Assess volume status and kidney function throughout treatment 2, 1
• Adjust therapy based on clinical response and laboratory parameters 2, 1

Common Pitfalls to Avoid

• Never use potassium citrate or other non-chloride potassium salts in metabolic alkalosis, as these worsen the condition by providing additional base 2, 1
• Avoid combining potassium-sparing diuretics with ACE inhibitors without close monitoring due to severe hyperkalemia risk 2, 1
• Do not use potassium-sparing diuretics in patients with significant renal dysfunction or existing hyperkalemia 2
• Avoid using two diuretics without potassium-sparing agents, as this markedly enhances electrolyte depletion risk 4
• Do not overlook Bartter syndrome in patients with unexplained metabolic alkalosis, especially with history of polyhydramnios and premature birth 2
• Hypochloremia and metabolic alkalosis antagonize loop diuretic effects, so correcting the alkalosis improves diuretic responsiveness 4