Metabolic Alkalosis: Biochemical Mechanisms, Pathophysiology, and Treatment

Abstract

Metabolic alkalosis is a primary pathophysiologic event characterized by the gain of bicarbonate or the loss of nonvolatile acid from extracellular fluid such that arterial pH increases (normal pH = 7.40). More simply put, it is a primary increase in plasma bicarbonate concentration (normal plasma HCO3 = 24mEq/L). Like all acid-base disturbances, metabolic alkalosis commonly complicates the course of patients with preexisting disorders. An understanding of its pathophysiology makes the diagnosis and management of metabolic alkalosis a relatively simple process. Several series (1,2) have reported that metabolic alkalosis is the second most common acid-base disorder in hospitalized adults (Table 1). Most of these are patients with other underlying diseases predisposing them to one of the many complex acid-base disorders.