In summary, the kidney possesses numerous mechanisms that help to prevent metabolic alkalosis. Maintenance of metabolic alkalosis for any length of time means that renal homeostatic mechanisms for HCO3- excretion have been disrupted. Understanding the mechanisms that may perturb the kidney's ability to correct alkalosis will lead to improved clinical approaches to differential diagnosis and treatment of the patient. Although metabolic alkalosis is frequently not dangerous, in certain settings metabolic alkalosis may contribute to mortality and should be treated aggressively.