ELECTROLYTES are chemical substances that separate, when dissolved in fluids, into electrically charged particles (ions) capable of conducting electric currents vital for the function of nerves and muscles.
The major cations (positively charged electroylytes) in the body's fluid supply are sodium, potassium, calcium, and magnesium. The major anions (negatively charged electrolytes) are chloride, phosphate, sulfate, and bicarbonate. Organic acids such as lactate, pyruvate, and aceto-acetate also carry negative ions.
Proteins are polyelectrolytes in that they carry many charges and may either be positively or negatively charged. In extracellular fluid, sodium is the major electrolyte with potassium present in much lower concentrations. The concentration of sodium can be 15 times higher than potassium in the extracellular fluid. Within the intracellular fluid, the situation is reversed with the major electrolyte being potassium while sodium is found in lesser concentrations. Here, concentrations of potassium can be 30 times greater than sodium.
Stability of electrolyte balance is dependent upon several factors. One is an adequate intake of water. Electrolytes are involved in metabolic activities and are vital to the function of all cells, therefore, when the body becomes dehydrated, electrolytes do not have sufficient fluid for mobility in order to function. Another factor is an adequate intake of electrolyte-containing foods. Still another is the homeostatic conditions within the body that can regulate the absorption, distribution, and excretion of water and its dissolved particles. Imbalances can occur when serum levels become either too high or too low usually resulting from renal disease or prolonged vomiting or diarrhea.
The following are major electrolytes and their functions:
  1. Sodium creates much of the osmotic pressure of extracellular fluid and is the most abundant cation in it. It is essential for electrical activity of neurons and muscle cells. An imbalance can cause hyponatremia or hypernatremia. Hyponatremia results when blood levels of sodium become too low usually caused by excessive sweating, diarrhea, or vomiting. Symptoms are dizziness, confusion, weakness, low blood pressure, and shock. Hypernatremia happens when the sodium blood levels become too high as a result of an excessive water loss or sodium ingestion. Symptoms are extreme thirst and agitation.
  2. Potassium creates much of the osmotic pressure in intracellular fluid and is the most abundant cation in it. It is essential for electrical activity of neurons and muscle cells. An imbalance can produce hypokalemia or hyperkalemia. Hypokalemia results when blood levels of potassium become too low and is usually a consequence of vomiting, diarrhea, or kidney disease. Symptoms are fatigue, confusion, and possible cardiac arrest. Hyperkalemia comes as a result of blood levels of potassium becoming too high and is usually a consequence of Addison's Disease with symptoms of weakness, abnormal sensations, cardiac arrhythmias, and possible arrest.
  3. Calcium is found most abundantly (98%) in bones and teeth with the remaining in tissues and fluids. It maintains normal excitability of neuons and muscle cells and is essential for blood clotting. An imbalance causes hypocalcemia or hypercalcemia. Hypocalcemia occurs when the blood levels of calcium become too low usually as a result of a decreased function of the parathyroid gland or a decreased calcium intake. Symptoms include muscle spasms leading to tetany (a continuous spasm). Hypercalcemia occurs when the parathyroid over functions. Such symptoms include muscle weakness, bone fragility, and possibly kidney stones.
  4. Magnesium is concentrated mostly in bone. It functions mainly in intracellular fluid rather than extracellular. It is essential for ATP production and activity of neurons and muscle cells.
  5. Chloride is the most abundant anion in extracellular fluid. It easily diffuses into and out of cells helping to regulate osmotic pressure. It is also part of the hydrochloric acid in the stomach.
  6. Bicarbonate is part of the buffer system.
  7. Phosphate is most abundant (85%) in bones and teeth. It functions primarily as an intracellular anion and is part of the nucleic acids - DNA, RNA, and ATP- as well as phospholipids and the phosphate buffer system.
  8. Sulfate is part of some amino acids and proteins in the form of sulfur.