What are the common causes of metabolic alkalosis?

From the Guidelines

Metabolic alkalosis is commonly caused by excessive loss of hydrogen ions or gain of bicarbonate in the body, with the most frequent causes including diuretic use, particularly loop diuretics like furosemide and thiazides like hydrochlorothiazide, as well as vomiting or nasogastric suction, and excessive administration of bicarbonate-containing medications or infusions. The use of diuretics, such as furosemide and hydrochlorothiazide, can lead to metabolic alkalosis by increasing renal excretion of chloride and hydrogen while retaining bicarbonate 1. Other causes of metabolic alkalosis include:

• Hypokalemia, which leads to increased hydrogen ion excretion by the kidneys
• Primary hyperaldosteronism, resulting in increased sodium reabsorption and potassium and hydrogen excretion
• Severe hypovolemia, which activates the renin-angiotensin-aldosterone system, promoting hydrogen ion excretion
• Milk-alkali syndrome from excessive calcium carbonate intake, and Bartter and Gitelman syndromes, genetic disorders affecting renal tubular function 1. It is essential to address the underlying factors, such as volume depletion, chloride depletion, or potassium depletion, to effectively treat metabolic alkalosis.

From the Research

Common Causes of Metabolic Alkalosis

The common causes of metabolic alkalosis can be categorized into several groups, including:

• Loss of acid through the kidney or gastrointestinal tract 2
• Diuretic therapy and prolonged nasogastric suctioning 3
• Volume depletion 3, 2, 4
• Excessive hydrogen ion loss by the gastrointestinal tract (e.g. vomiting) 2, 4
• Exogenous base gain 4
• Use of loop diuretics 4
• Hypokalemia 5, 4
• Hyperaldosteronism 2, 4
• Renal failure 4

Factors that Maintain Metabolic Alkalosis

In addition to the causes of metabolic alkalosis, there are several factors that maintain the abnormality, including:

• Extracellular fluid volume status 2, 6, 4
• Hormonal systems (e.g. hyperaldosteronism) 2, 4
• Chloride depletion 2, 4
• Hypovolemia 4

Treatment of Metabolic Alkalosis

The treatment of metabolic alkalosis is directed toward correction of dehydration and removal of the precipitating cause when possible 3. This may involve:

• Correction of existing depletions (e.g. potassium chloride infusion) 4
• Prevention of further losses 4
• Hemodialysis with a high chloride dialysate, with or without hydrochloric acid infusion 3