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Simple and mixed acid-base disorders

Michael Emmett, MD
Biff F Palmer, MD
Section Editor
Richard H Sterns, MD
Deputy Editor
John P Forman, MD, MSc


Each day, adults generate large amounts of acids that must be expired, excreted, metabolized to non-charged neutral molecules, and/or buffered to avoid fatal acidemia. These acids are of three major classes:

Approximately 15,000 mmol (considerably more with exercise) of carbon dioxide (CO2) is produced each day, which combines with water to form carbonic acid (H2CO3).

Metabolic reactions generate several thousand mmol per day of organic acids, such as lactic acid and citric acid. These acids are metabolized to neutral products (such as glucose) and to CO2 and water. Normally, the generation and utilization rates of these organic acids are equal so that their steady state concentration in the extracellular fluid is relatively low and stable.

Approximately 50 to 100 meq of nonvolatile acid is produced each day (mostly sulfuric acid derived from the metabolism of sulfur-containing amino acids in the diet).

Acid-base balance is maintained by normal pulmonary excretion of carbon dioxide, metabolic utilization of organic acids, and renal excretion of nonvolatile acids.


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Literature review current through: Sep 2016. | This topic last updated: Oct 18, 2016.
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