1.
Hypokalemia in Emergency Medicine http://emedicine.medscape.com/article/767448-overview
Author: David Garth, MD; Chief Editor: Erik D Schraga, MD more...
Updated: Apr 2, 2010
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.
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.
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.
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 and
American College of Emergency Physicians
Disclosure: Nothing to disclose.
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Hypokalemia in Emergency Medicine http://emedicine.medscape.com/article/767448-overview
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: eMedicine 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.
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Hypokalemia in Emergency Medicine http://emedicine.medscape.com/article/767448-overview
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