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Electrolytes

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

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

References

Hamm LL, DuBose TD. Disorders of acid-base balance. In: Yu ASL, Chertow GM,  Luyckx VA, Marsden PA, Skorecki K, Taal MW, eds. Brenner and Rector's The Kidney. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 16.

Oh MS, Briefel G. Evaluation of renal function, water, electrolytes, and acid-base balance. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 14.

Review Date 9/24/2019

Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.