How to correct metabolic alkalosis?

How to Correct Metabolic Alkalosis

The correction of metabolic alkalosis depends primarily on identifying whether it is chloride-responsive (saline-responsive) or chloride-resistant, then addressing the underlying cause with appropriate fluid, electrolyte replacement, and pharmacologic interventions when conservative measures fail. 1

Initial Assessment and Classification

Determine the urinary chloride concentration to classify the alkalosis type, as this guides treatment strategy 1:

• Chloride-responsive alkalosis (urinary Cl <20 mEq/L): typically from volume depletion, vomiting, or diuretic use
• Chloride-resistant alkalosis (urinary Cl >20 mEq/L): suggests mineralocorticoid excess, Bartter syndrome, or Gitelman syndrome 1

Assess volume status, blood pressure (supine and standing), and measure serum potassium and chloride levels 2

Treatment Based on Etiology

Chloride-Responsive Alkalosis (Most Common)

First-line treatment is isotonic saline (0.9% NaCl) to restore intravascular volume and provide chloride for renal bicarbonate excretion 1, 2:

• Administer IV normal saline to correct volume depletion 2
• This allows the kidneys to excrete excess bicarbonate once chloride is repleted 3

Potassium chloride supplementation is essential when hypokalemia is present 1:

• Doses of 20-60 mEq/day are frequently required to maintain serum potassium in the 4.5-5.0 mEq/L range 1
• Use only potassium chloride, not potassium citrate, as citrate can worsen metabolic alkalosis 1

Discontinue or reduce diuretic doses if clinically feasible 1

Diuretic-Induced Alkalosis

Add a potassium-sparing diuretic as first-line pharmacologic intervention 1:

• Amiloride is the most effective potassium-sparing diuretic for metabolic alkalosis, starting at 2.5 mg daily, titrated up to 5 mg daily 1
• Spironolactone 25 mg daily (titrated to 50-100 mg daily) is an alternative, particularly in heart failure patients 1, 4
• Avoid combining potassium-sparing diuretics with ACE inhibitors without close monitoring due to hyperkalemia risk 1
• Do not use in patients with significant renal dysfunction or existing hyperkalemia 1

Acetazolamide is useful in patients with heart failure and adequate kidney function 1, 5:

• Dose: 500 mg IV as a single dose 5
• Onset of action within 2 hours, with maximal effect at approximately 15.5 hours 5
• Causes rapid fall in serum bicarbonate (mean reduction 6.4 mmol/L at 24 hours) with normalization of pH 5
• Effect persists for 48 hours 5

Severe or Refractory Metabolic Alkalosis

For severe alkalosis unresponsive to conservative measures, consider acid administration 3, 2:

• Dilute hydrochloric acid (0.1-0.2 N HCl) via central venous catheter is the treatment of choice for patients with hepatic dysfunction or severe renal impairment 3, 2
• Ammonium chloride IV is an alternative but requires hepatic conversion and should be avoided in liver disease 3

Hemodialysis with low-bicarbonate/high-chloride dialysate is the definitive treatment for refractory cases, especially with concurrent renal failure 1:

• This is the treatment of choice when medical management fails 1
• Particularly important in patients with volume overload who cannot tolerate saline administration 4

Special Conditions

Bartter or Gitelman syndrome (chloride-resistant alkalosis) 1:

• Sodium chloride supplementation: 5-10 mmol/kg/day 1
• Potassium chloride for potassium repletion 1
• NSAIDs for symptomatic patients (with gastric acid inhibitors for gastroprotection) 1
• Consider genetic testing for definitive diagnosis 1

Heart failure patients 4:

• Appropriate management of circulatory failure is integral to treatment 4
• Add aldosterone antagonist (spironolactone) to the diuretic regimen 1, 4
• Acetazolamide is particularly useful in this population with adequate kidney function 1, 4

Critical Pitfalls to Avoid

Do not use sodium bicarbonate or alkalinization strategies - these are contraindicated and will worsen the alkalosis 1

Do not use furosemide unless hypervolemia, hyperkalemia, and/or renal acidosis are present 6 - loop diuretics perpetuate the alkalosis

Avoid potassium salts other than potassium chloride (such as potassium citrate), which can worsen metabolic alkalosis 1

Do not delay dialysis in severe cases while attempting medical management - severe alkalosis with renal failure is refractory to conservative measures 1

Monitoring Requirements

Monitor serum electrolytes, acid-base status (pH, bicarbonate, PCO2), and volume status regularly during treatment 1

Adjust therapy based on clinical response and laboratory parameters 1

In heart failure patients with diuretic-induced alkalosis, the combination of volume management, aldosterone antagonism, and judicious use of acetazolamide provides the most effective approach 4