Definition

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:

• Ionized calcium
• Serum calcium
• Serum chloride
• Serum magnesium
• Serum phosphorus
• Serum potassium
• Serum sodium

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, Pincus MR. 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. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 15.