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Electrolytes i-+lek-tru-!lIt

by James L. Lewis, III, MD

Some minerals—especially the macrominerals (minerals the body needs in relatively large amounts)—are important as electrolytes. The body uses electrolytes to help regulate nerve and muscle function and to maintain acid-base balance (see Overview of Acid-Base Balance) and water balance (see Water Balance).

To function normally, the body must keep fluid levels from varying too much in the areas of the body that contain fluid (called compartments). The three main compartments are

  • Fluid within cells

  • Fluid in the space around cells

  • Blood

Electrolytes, particularly sodium, help the body maintain normal fluid levels in these compartments (called fluid balance) because the amount of fluid a compartment contains depends on the concentration of electrolytes in it. If the electrolyte concentration is high, fluid moves into that compartment. If the electrolyte concentration is low, fluid moves out of that compartment. To adjust fluid levels, the body can actively move electrolytes in or out of cells. Thus, having electrolytes in the right concentrations (called electrolyte balance) is important in maintaining fluid balance among the compartments.

The kidneys help maintain electrolyte concentrations by filtering electrolytes from blood, returning some electrolytes to the blood, and excreting any excess into the urine. Thus, the kidneys help maintain a balance between daily consumption and excretion.

If the balance of electrolytes is disturbed, disorders can develop. An electrolyte imbalance can result from the following:

  • Becoming dehydrated

  • Taking certain drugs

  • Having certain heart, kidney, or liver disorders

  • Being given intravenous fluids or feedings in inappropriate amounts