Electrolytes

Share this page:
Looking for your tests results? Looking for reference ranges?
Also known as: Lytes
Formal name: Electrolyte Panel

At a Glance

Why Get Tested?

To detect a problem with the body's fluid and electrolyte balance

When to Get Tested?

As part of routine health screening, when your doctor suspects that you have an excess or deficit of one of the electrolytes (usually sodium or potassium), or if your doctor suspects an acid-base imbalance

Sample Required?

A blood sample drawn from a vein in the arm

Test Preparation Needed?

None

The Test Sample

What is being tested?

Electrolytes are electrically charged minerals that are found in body tissues and blood in the form of dissolved salts. They help move nutrients into and wastes out of the body's cells, maintain a healthy water balance, and help stabilize the body’s pH level. The electrolyte panel measures the main electrolytes in the body: sodium (Na+), potassium (K+), chloride (Cl-), and bicarbonate (HCO3-; sometimes reported as total CO2).

Most sodium is found in the plasma, outside of the body's cells, where it helps to regulate the amount of water in the body. Potassium is found primarily inside the body's cells. A small but vital amount of potassium is found in the plasma, the liquid portion of the blood. Monitoring potassium is important. Small changes in the plasma K+ level can affect the heart’s rhythm and ability to contract. Chloride travels in and out of the cells to help maintain electrical neutrality, and its level usually mirrors that of sodium. The primary role of bicarbonate (or total CO2, an estimate of bicarbonate), which is excreted and reabsorbed by the kidneys, is to help maintain a stable pH level (acid-base balance) and, secondarily, to help maintain electrical neutrality.

A person's diet provides sodium, potassium, and chloride; the kidneys excrete them. The lungs provide oxygen and regulate CO2, which is in balance with bicarbonate. The balance of these chemicals is an indication of the functional well-being of several basic body functions, including those performed by the kidneys and heart.

The electrolyte panel is composed of the individual tests for sodium, potassium, chloride, and bicarbonate (or total CO2). A related "test" is the anion gap, which is a value calculated using the results of an electrolyte panel. It reflects the difference between the positively charged ions (called cations) and the negatively charged ions (called anions). The occurrence of an abnormal anion gap reflects an unusual presence of some kind of charged particle in the blood. It is non-specific but can be affected by metabolic by-products from conditions such as starvation or diabetes or the presence of a toxic substance, such as oxalate, glycolate, or aspirin. For more information on anion gap, see Common Questions #1.

How is the sample collected for testing?

A blood sample is drawn by needle from a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

Common Questions

Ask a Laboratory Scientist

Form temporarily unavailable

Due to a dramatic increase in the number of questions submitted to the volunteer laboratory scientists who respond to our users, we have had to limit the number of questions that can be submitted each day. Unfortunately, we have reached that limit today and are unable to accept your inquiry now. We understand that your questions are vital to your health and peace of mind, and recommend instead that you speak with your doctor or another healthcare professional. We apologize for this inconvenience.

This was not an easy step for us to take, as the volunteers on the response team are dedicated to the work they do and are often inspired by the help they can provide. We are actively seeking to expand our capability so that we can again accept and answer all user questions. We will accept and respond to the same limited number of questions tomorrow, but expect to resume the service, 24/7, as soon as possible.

Article Sources

« Return to Related Pages

NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

ARUP Lab Tests. Electrolyte Panel. Available online at http://www.aruplab.com/guides/ug/tests/0020410.jsp through http://www.aruplab.com. Accessed September 2011. 

Mayo Medical Laboratories. 87972 Overview: Electrolyte Panel, Serum. Available online at http://www.mayomedicallaboratories.com/test-catalog/print.php?unit_code=87972 through http://www.mayomedicallaboratories.com. Accessed September 2011. 

Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.

Carlson, R. and Abbas, A. (2001). Use Of Anion Gap In Acid-Base Defects In The Acutely Ill. Medical Online Review and Database, Snow Tiger Medical Systems [On-line information]. Available online at http://www.snowtigermed.com/cgi-local/viewarticle.pl?doc=991203131636 through http://www.snowtigermed.com.

Martin, L. (1999 February). 2. Anion and bicarbonate gaps for diagnosing mixed acid-base disorders. All You Really Need to Know to Interpret Arterial Blood Gases [On-line, Ch 2 of book published by Lippincott Williams & Wilkins]. Available online at http://www.mtsinai.org/pulmonary/noninvasive/gaps.htm through http://www.mtsinai.org.

Fall, P. (2000 March). A stepwise approach to acid-base disorders, Practical patient evaluation for metabolic acidosis and other conditions. Postgraduate Medicine online, 107 (3) [On-line journal]. Available online at http://www.postgradmed.com/issues/2000/03_00/fall.htm through http://www.postgradmed.com.

Brandis, K. (2002 August 14) 3.2 The Anion Gap. Acid-Base Physiology [On-line textbook]. Available online at http://www.qldanaesthesia.com/AcidBaseBook/AB3_2.htm through http://www.qldanaesthesia.com.

Brandis, K. (2002 August 14) 3.4 The Urinary Anion Gap. Acid-Base Physiology [On-line textbook]. Available online at http://www.qldanaesthesia.com/AcidBaseBook/AB3_4.htm through http://www.qldanaesthesia.com.

Harrison, J. (1997 January 5, Modified). Metabolic (including renal) Acid-Base Imbalance. Tulane Medical Pathology Course [On-line information, “classware”]. Available online at http://www.mcl.tulane.edu/classware/pathology/medical_pathology/acid-base-elect/12Metab_problems.html through http://www.mcl.tulane.edu.

(2003) Anion Gap. Michigan State Univ, Dept of Physiology [On-line information for class 442]. Available online: at http://www.psl.msu.edu/class/442/anion_gap.htm through http://www.psl.msu.edu.

(1995-2004). Chapter 59. Disorders of Acid-Base Metabolism. The Merck Manual of Geriatrics [On-line information]. Available online at http://www.merck.com/mrkshared/mm_geriatrics/sec8/ch59.jsp through http://www.merck.com.

(1995-2004). Acid-Base Metabolism. The Merck Manual of Diagnosis and Therapy, Section 2. Endocrine And Metabolic Disorders, Chapter 12. Water, Electrolyte, Mineral, And Acid-Base Metabolism [On-line information]. Available online at http://www.merck.com/mrkshared/mmanual/section2/chapter12/12g.jsp through http://www.merck.com.

Hornick, D., Editor (2003, Revised). An Approach to the Analysis of Arterial Blood Gases and Acid-Base Disorders. Virtual Hospital, University of Iowa Health Care [On-line information]. Available online at http://www.vh.org/adult/provider/internalmedicine/bloodgases/ through http://www.vh.org.

Priestley, M. and Lieh-Lai, M. (2004 March 8, Updated). Excerpt from Acidosis, Metabolic. EMedicine [On-line information]. Available online at http://www.emedicine.com/ped/byname/acidosis-metabolic.htm through http://www.emedicine.com.

Jones, J. and Bosker, G. (2002 December 16) Diagnostic Aids in Emergency Medicine. The Emergency Medicine Reports Textbook of Adult and Pediatric Emergency Medicine [Excerpt from On-line Clinical Textbook]. Available online at http://www.thrombosis-consult.com/articles/Textbook/146_diagnosticaids.htm and http://www.thrombosis-consult.com/ClinicalTextbooks2.htm through http://www.thrombosis-consult.com.

Beaven, A. (2002 July 12). Ethylene Glycol and Methanol Toxicity. Univ of NC at Chapel Hill, Department of Internal Medicine [On-line information]. PDF available for download at http://www.med.unc.edu/medicine/web/ethyleneglycol.pdf through http://www.med.unc.edu.

(2002). Acid-Base Emergencies, Part 1. Texas Society for Respiratory Care [On-line information]. Available online at http://www.tsrc.org/cert005/ through http://www.tsrc.org.

Welch, J. (1998 April 30, Modified). Increased Anion Gap Metabolic Acidosis. Georgetown University, NetScut [On-line information]. Available online at http://www.family.georgetown.edu/welchjj/netscut/acid_base/Increased_Anion_Gap_Metabolic_Acidosis.html through http://www.family.georgetown.edu.

Welch, J. (1998 April 30, Modified). Normal Anion Gap Metabolic Acidosis. Georgetown University, NetScut [On-line information]. Available online at http://www.family.georgetown.edu/welchjj/netscut/acid_base/Normal_Anion_Gap_Metabolic_Acidosis.html through http://www.family.georgetown.edu.

(1995-2004). Minerals and Electrolytes. The Merck Manual of Medical Information – Second Home Edition [On-line information]. Available online at http://www.merck.com/mmhe/sec12/ch155/ch155a.html?qt=electrolytes&alt=sh through http://www.merck.com.

Ben-Joseph, E., Reviewed (2004 July). Dehydration. Familydoctor.org Information for Parents [On-line information]. Available online at http://www.kidshealth.org/PageManager.jsp?dn=familydoctor&lic=44&article_set=21646 through http://www.kidshealth.org.

Webner, D., Updated (2003 August 18). CO2. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003469.htm.

A.D.A.M. editorial, Updated (2003 October 15). Electrolytes. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/002350.htm.

Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry. AACC Press, Washington, DC. Pp 333-337.

Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson R, Pincus M, eds. Philadelphia, PA: Saunders Elsevier: 2007.

(August 14, 2007). MedlinePlus Medical Encyclopedia, Electrolytes. Available online athttp://www.nlm.nih.gov/medlineplus/ency/article/002350.htm. Accessed May 2008.