By Dr Ananya Mandal, MD
Electrolytes are essential substances in the body required for cell function and cell signalling. In the human body, the main electrolytes are:
- Sodium (Na+)
- Potassium (K+)
- Calcium (Ca2+)
- Magnesium (Mg2+)
- Chloride (Cl−)
- Hydrogen phosphate (HPO42−)
- Hydrogen carbonate (HCO3−).
The plus or minus symbol indicates the ionic nature of the substance and its either positive or negative charge as a result of dissociation.
Importance of electrolytes
These electrolytes are essential to various bodily functions and an electrolyte imbalance can be dangerous and even life threatening, depending on the clinical scenario. The balance of electrolyte levels is therefore carefully maintained in the body and may be checked in the blood or urine as a measure of health. This complex and subtle balance needs to be maintained between the intracellular and extracellular environments. In particular, the osmotic gradient of electrolytes must be carefully maintained in order to ensure a healthy blood pH and an adequate level of hydration, factors that are essential for the proper function of muscles and nerves. Several mechanisms exist to help regulate the electrolyte concentration in the body.
Muscles and nerves are both stimulated by the activity of electrolytes in the intracellular, extracellular and interstitial fluid. Ion channels exist on the surface of the cell membrane to transport electrolytes to and from the cell. For instance, muscle contraction depends on the presence of potassium, calcium and sodium ions and insufficient levels of these ions may lead to muscle weakness or spasms.
If an electrolyte imbalance has been caused by electrolyte loss through diarrhea or vomiting, for example, an oral rehydration solution (ORS) containing electrolytes and fluids can be used to replenish the body. In severe cases of electrolyte loss, an intravenous (IV) route of administration may be necessary. A severe electrolyte imbalance can cause neurological and cardiac complications and may be fatal if not recognised and treated promptly.
Reviewed by Sally Robertson, BSc
Last Updated: Jun 2, 2014