Metabolic Alkalosis

- Loss of fixed H+ or gain of base produces a decrease in arterial [H+] (alkalemia)
- As a result, arterial [HCO3-] increases.  This increase is the primary disturbance.
- For example, in vomiting, H+ is lost from the stomach, HCO3- remains behind in the blood, and the [HCO3-] increases.
- Alkalemia causes hypoventilation, which is the respiratory compensation for metabolic alkalosis.
- Renal correction of metabolic alkalosis consists of increased excretion of HCO3- b/c the filtered load of HCO3- exceeds the ability of the renal tubule to reabsorb it.
- If metabolic alkalosis is accompanied by ECF volume contraction (e.g, vomiting), the reabsorption of HCO3- increases (secondary to ECF volume contraction), worsening the metabolic alkalosis.