From the Research
Anion gap metabolic alkalosis is actually a misnomer, as anion gap refers to metabolic acidosis, not alkalosis. Metabolic alkalosis occurs when there is an excess of bicarbonate or loss of acid in the body, leading to an elevated pH. Common causes of metabolic alkalosis include:
- Vomiting or nasogastric suction (which removes gastric acid)
- Diuretic use (particularly loop and thiazide diuretics like furosemide and hydrochlorothiazide)
- Hypokalemia
- Excessive alkali administration (such as sodium bicarbonate)
- Severe hypovolemia Certain endocrine disorders like hyperaldosteronism, Cushing's syndrome, and Bartter syndrome can also cause metabolic alkalosis. The underlying mechanism typically involves increased renal reabsorption of bicarbonate, often due to volume depletion or potassium deficiency.
As noted in the study by 1, underlying causes of metabolic alkalosis may be evident from history, evaluation of effective circulatory volume, and measurement of urine chloride concentration. However, identification of causes may be difficult for certain conditions associated with clandestine behaviors. Treatment should address the underlying cause, such as volume repletion with normal saline for contraction alkalosis, potassium replacement for hypokalemia, or discontinuation of offending medications. In severe cases, acetazolamide 250-500mg orally or intravenously may be used to promote bicarbonate excretion, or dilute hydrochloric acid may be administered in critical situations under careful monitoring.
It's worth noting that the concept of anion gap is more commonly associated with metabolic acidosis, as discussed in studies such as 2, 3, 4, and 5. However, these studies do not directly address the topic of anion gap metabolic alkalosis, and therefore, the most relevant information comes from the study by 1, which highlights the importance of considering clandestine behaviors and measuring urine chloride concentration in the diagnosis of metabolic alkalosis.