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Electrolytes are minerals in your blood and other body fluids that carry an electric charge.

Electrolytes affect how your body functions in many ways, including:

  • The amount of water in your body
  • The acidity of your blood (pH)
  • Your muscle function
  • Other important processes

You lose electrolytes when you sweat. You must replace them by drinking fluids that contain electrolytes. Water does not contain electrolytes.

Common electrolytes include:

  • Calcium
  • Chloride
  • Magnesium
  • Phosphorus
  • Potassium
  • Sodium

Electrolytes can be acids, bases, or salts. They can be measured by different blood tests. Each electrolyte can be measured separately, such as:

Note: Serum is the part of blood that doesn't contain cells.

Sodium, potassium, and chloride levels can also be measured as part of a basic metabolic panel. A more complete test, called comprehensive metabolic panel, can test for these several more electrolytes.

The electrolytes - urine test measures electrolytes in urine. It test the levels of calcium, chloride, potassium, sodium, and other electrolytes.


Chernecky CC, Berger BJ. Electrolytes panel - blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St. Louis, MO: Elsevier Saunders; 2013:464-467.

DuBose TD. Disorders of acid-base balance. In: Taal MW, Chertow GM, Marsden PA, et al, eds. Brenner and Rector's The Kidney. 9th ed. Philiadelphia, PA: Elsevier Saunders; 2012:chap16.

Review Date 8/29/2015

Updated by: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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