Hypokalemia in Emergency Medicine 

  • Author: David Garth, MD; Chief Editor: Erik D Schraga, MD   more...
 
Updated: Apr 25, 2012
 

Background

Potassium is one of the body's major ions. Nearly 98% of the body's potassium is intracellular. The ratio of intracellular to extracellular potassium is important in determining the cellular membrane potential. Small changes in the extracellular potassium level can have profound effects on the function of the cardiovascular and neuromuscular systems.[1, 2, 3]

The kidney determines potassium homeostasis, and excess potassium is excreted in the urine.

The reference range for serum potassium level is 3.5-5 mEq/L, with total body potassium stores of approximately 50 mEq/kg (ie, approximately 3500 mEq in a 70-kg person).

Hypokalemia is defined as a potassium level less than 3.5 mEq/L.

Moderate hypokalemia is a serum level of 2.5-3 mEq/L.

Severe hypokalemia is defined as a level less than 2.5 mEq/L.

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Pathophysiology

Hypokalemia may result from conditions as varied as renal or GI losses, inadequate diet, transcellular shift (movement of potassium from serum into cells), and medications.

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Epidemiology

Frequency

United States

As many as 20% of hospitalized patients are hypokalemic; however, hypokalemia is clinically significant in only about 4-5% of these patients. Severe hypokalemia is relatively uncommon.

Up to 14% of outpatients who undergo laboratory testing are found to be mildly hypokalemic.

Approximately 80% of patients who are receiving diuretics become hypokalemic.

Sex

Incidence is equal in males and females.

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Contributor Information and Disclosures
Author

David Garth, MD  Attending Physician, Department of Emergency Medicine, Mary Washington Hospital

David Garth, MD is a member of the following medical societies: American Academy of Emergency Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Robin R Hemphill, MD, MPH  Associate Professor, Director, Quality and Safety, Department of Emergency Medicine, Emory University School of Medicine

Robin R Hemphill, MD, MPH is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Howard A Bessen, MD  Professor of Medicine, Department of Emergency Medicine, University of California, Los Angeles, David Geffen School of Medicine; Program Director, Harbor-UCLA Medical Center

Howard A Bessen, MD is a member of the following medical societies: American College of Emergency Physicians

Disclosure: Nothing to disclose.

John D Halamka, MD, MS  Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center

John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Chief Editor

Erik D Schraga, MD  Staff Physician, Department of Emergency Medicine, Mills-Peninsula Emergency Medical Associates

Disclosure: Nothing to disclose.

Additional Contributors

I would like to thank my wife, Mary. Her patience, love, and reassurance, are my bedrock.

References

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