December 18, 2004
Q: Is it important to replace electrolytes lost from exercise? - Layperson
A: It is very important to replace both electrolytes and water, together, and not just one or the other to maintain a properly functioning body.
Electrolytes are salts in the body that conduct electricity and are found in the body, fluid, tissue, and blood. Examples are chloride, calcium, magnesium, sodium, and potassium. Sodium (Na+) is concentrated in the extracellular fluid between tissue cells and potassium (K+) is concentrated in the intracellular fluid within the blood vessels. Proper balance is essential for muscle coordination, heart function, fluid absorption and excretion, nerve function, and concentration.
Electrolytes are vital to one's health and survival. They are positively and negatively charged particles (ions) that are formed when mineral or other salts dissolve and separate (dissociate) in water. Since electrolytes carry a charge, they can conduct electrical current in water, which itself in its pure form is a poor conductor of electricity. This characteristic of electrolytes is important because the current enables electrolytes to regulate how and where fluids are distributed throughout the body, which includes keeping water from floating freely across cell membranes.
Basically, cells need to be bathed in fluids inside and out. To control fluid passage across cell membranes, cells regulate the movement of electrolytes into and out of them, which causes water to follow the charged particles around wherever they go. These actions help maintain a state of fluid balance. This is also how electrolytes transport nutrients into cells and wastes out of them. The difference in electrical balance inside and outside of cells also allows for transmission of nerve impulses, contraction or relaxation of muscles, blood pressure control, and proper gland functioning. In addition, the presence of electrolytes determines the acidity or pH of some fluids, especially blood.
As you can see, our bodies have developed mechanisms to keep electrolytes within specific ranges. If one loses large amounts of fluids quickly, however, electrolytes may become unbalanced. This imbalance can occur through vomiting, diarrhea, excessive sweating (especially intense exercise), serious burns, or wounds. In these cases, water and electrolytes need to be replaced. Life-threatening conditions may result if the losses are severe.
The kidneys regulate fluid absorption and excretion and maintain a narrow range of electrolyte fluctuation. Normally, sodium and potassium are filtered and excreted in the urine and feces according to the bodies needs. Too much or too little sodium or potassium, caused by poor diet, dehydration, medication, and disease, results in an imbalance. Too much sodium is called hypernatremia; too little is called hyponatremia. Too much potassium is called hyperkalemia; too little is called hypokalemia.
Incidence and Prevalence
Hyponatremia is the most common electrolyte imbalance. It is associated with kidney disease such as nephrotic syndrome and acute renal failure (ARF). Men and women with healthy kidneys have equal chances of experiencing electrolyte imbalance, and people with eating disorders such as anorexia and bulimia, which most often affect women, are at increased risk. Very young people and old people are affected more often than young adults.
CausesHyponatremia is caused by conditions such as water retention and renal failure that result in a low sodium level in the blood.
Pseudohyponatremia occurs when too much water is drawn into the blood; it is commonly seen in people with hypoglycemia (low blood sugar).
Psychogenic polydipsia occurs in people who compulsively drink more than four gallons of water a day.
Hypovolemic hyponatremia (with low blood volume due to fluid loss) occurs in dehydrated people who rehydrate (drink a lot of water) too quickly, in patients taking thiazide diuretics, and after severe vomiting or diarrhea.
Hypervolemic hyponatremia (high blood volume due to fluid retention) occurs in people with live cirrhosis, heart disease, or nephrotic syndrome. Edema (swelling) often develops with fluid retention.
Euvolemic hyponatremia (decrease in total body water) occurs in people with hypothyroidism, adrenal gland disorder, and disorders that increase the release of the antidiuretic hormone (ADH), such as tuberculosis, pneumonia, and brain trauma.
Signs and SymptomsSymptoms of hyponatremia are related to the severity and the rate at which the conditions develop. The first symptoms are fatigue, weakness, nausea, and headache. More severe cases cause confusion, seizure, coma, and death.
The goal of treatment is to restore electrolyte balance for proper hydration and use of total body fluid. Sodium deficiency must be corrected slowly because drastic change in sodium level can cause brain cell shrinkage and central pontine myelinolysis (damage to the pons region of the brain). Methods include:
DISCLAIMER: The information in this column, is NOT intended to diagnose and/or treat any health related issues and is provided solely for informational purposes only. Consult the appropriate healthcare professional before making any changes to your healthcare regime. Even what may seem like simple changes in the diet for example, can interact with, and alter, the efficiency of medications and/or the body's response to the medications. Many herbs and supplements exert powerful medicinal effects. Neither the author, nor the website designers, assume any responsibility for the reader's use or misuse of this information.