Review Article | Published:

Metabolic acidosis: pathophysiology, diagnosis and management

Nature Reviews Nephrology volume 6, pages 274285 (2010) | Download Citation

Abstract

Metabolic acidosis is characterized by a primary reduction in serum bicarbonate (HCO3) concentration, a secondary decrease in the arterial partial pressure of carbon dioxide (PaCO2) of 1 mmHg for every 1 mmol/l fall in serum HCO3 concentration, and a reduction in blood pH. Acute forms (lasting minutes to several days) and chronic forms (lasting weeks to years) of the disorder can occur, for which the underlying cause/s and resulting adverse effects may differ. Acute forms of metabolic acidosis most frequently result from the overproduction of organic acids such as ketoacids or lactic acid; by contrast, chronic metabolic acidosis often reflects bicarbonate wasting and/or impaired renal acidification. The calculation of the serum anion gap, calculated as [Na+] – ([HCO3] + [Cl]), aids diagnosis by classifying the disorders into categories of normal (hyperchloremic) anion gap or elevated anion gap. These categories can overlap, however. Adverse effects of acute metabolic acidosis primarily include decreased cardiac output, arterial dilatation with hypotension, altered oxygen delivery, decreased ATP production, predisposition to arrhythmias, and impairment of the immune response. The main adverse effects of chronic metabolic acidosis are increased muscle degradation and abnormal bone metabolism. Using base to treat acute metabolic acidosis is controversial because of a lack of definitive benefit and because of potential complications. By contrast, the administration of base for the treatment of chronic metabolic acidosis is associated with improved cellular function and few complications.

Key points

  • Categorizing metabolic acidosis into acute and chronic varieties can be valuable for anticipating adverse effects and for determining the risks and benefits of therapy

  • A systematic approach to diagnosis of metabolic acidosis is valuable; use of the serum anion gap is an important initial tool although its limitations should be understood

  • The adverse effects of acute metabolic acidosis primarily involve the cardiovascular system, whereas the adverse effects of chronic metabolic acidosis primarily involve the musculoskeletal system

  • The treatment of acute metabolic acidosis with the administration of base has not proven beneficial in improving cardiovascular function; alternative therapies are needed

  • The treatment of chronic metabolic acidosis with the administration of base is beneficial but the goal of therapy remains unclear

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Acknowledgements

J. A. Kraut's work is supported in part by research funds from the Veterans Administration.

C. P. Vega, University of California, Irvine, CA, is the author of and is solely responsible for the content of the learning objectives, questions and answers of the MedscapeCME-accredited continuing medical education activity associated with this article.

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  1. Division of Nephrology, Veterans Administration Greater Los Angeles (VHAGLA) Healthcare System, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA

    • Jeffrey A. Kraut
  2. Department of Medicine, Division of Nephrology, St Elizabeth's Medical Center, 736 Cambridge Street, Boston, MA 02135, USA

    • Nicolaos E. Madias

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The authors declare no competing financial interests.

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Correspondence to Nicolaos E. Madias.

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https://doi.org/10.1038/nrneph.2010.33

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