What are the common causes of metabolic alkalosis?

From the Guidelines

Metabolic alkalosis is primarily caused by excessive loss of hydrogen ions or gain of bicarbonate in the body, with common causes including vomiting, diuretic use, excessive bicarbonate administration, hypokalemia, and certain endocrine disorders like Bartter syndrome, as noted in a 2021 study published in Kidney International 1.

Common Causes of Metabolic Alkalosis

The most common causes of metabolic alkalosis include:

• Vomiting or nasogastric suction, which directly removes gastric acid from the body
• Diuretic use, particularly loop diuretics like furosemide and thiazides like hydrochlorothiazide, as they increase renal excretion of chloride and hydrogen ions while retaining bicarbonate
• Excessive administration of bicarbonate-containing medications or antacids, which directly increases serum bicarbonate levels
• Hypokalemia, as potassium depletion leads to increased hydrogen ion excretion by the kidneys
• Severe hypovolemia, causing contraction alkalosis, where decreased blood volume concentrates existing bicarbonate
• Certain endocrine disorders like hyperaldosteronism, Cushing's syndrome, and Bartter syndrome, which promote renal potassium and hydrogen ion loss, as discussed in the context of Bartter syndrome in 1 ### Less Common Causes Less common causes of metabolic alkalosis include:
• Milk-alkali syndrome, resulting from excessive calcium and absorbable alkali intake
• Post-hypercapnic alkalosis following rapid correction of chronic respiratory acidosis
• Other rare tubulopathies exhibiting metabolic alkalosis, as listed in Table 4 of the study 1 ### Diagnostic Considerations When diagnosing metabolic alkalosis, it is essential to distinguish renal from gastrointestinal potassium loss and potassium shifts, and to consider the role of urinary chloride excretion in assessing the underlying cause, as noted in 1.

From the Research

Causes of Metabolic Alkalosis

The common causes of metabolic alkalosis can be divided into several categories, including:

• Chloride depletion alkalosis, which can be caused by excessive vomiting or the use of loop diuretics 2, 3, 4
• Mineralocorticoid excess syndromes, such as aldosterone excess or cortisol excess 3, 5, 4, 6
• Apparent mineralocorticoid excess syndromes, such as licorice ingestion 3, 5, 6
• Excess alkali administration, which can be caused by oral or parenteral alkali intake 3, 5, 4, 6
• Loss of acid via the gastrointestinal tract or the kidney 2, 3, 5, 6
• Net accumulation of bicarbonate within the extracellular fluid 6

Factors that Maintain Metabolic Alkalosis

Several factors can contribute to the maintenance of metabolic alkalosis, including:

• Volume contraction or hypovolemia 2, 3, 5, 6
• Low glomerular filtration rate or renal failure 2, 3, 5, 6
• Potassium deficiency or hypokalemia 2, 3, 5, 6
• Hypochloremia or low chloride levels 2, 3, 5, 6
• Aldosterone excess 2, 3, 5, 6
• Elevated arterial carbon dioxide 6

Clinical States Associated with Metabolic Alkalosis

Metabolic alkalosis can be associated with several clinical states, including:

• Vomiting 2, 3, 5, 6
• Mineralocorticoid excess syndromes, such as aldosterone excess or cortisol excess 3, 5, 4, 6
• Licorice ingestion 3, 5, 6
• Diuretic administration, particularly loop diuretics 2, 3, 5, 6
• Bartter's and Gitelman's syndromes, which are genetic diseases 3, 5, 6
• Cystic fibrosis 6