What Are Electrolytes?

Reprinted from Eating Disorders Today
By Michael Myers, MD
Summer 2004 Volume 2, Number 4
©2002 Gürze Books

What Are Electrolytes?
Electrolytes are the salts in your body. The most common salts are sodium, potassium, and chloride. Often associated with abnormalities in electrolytes are abnormalities in the bicarbonate level. Although not technically an electrolyte, bicarbonate is important in maintaining the body's acid base balance. Located in the blood and cells, electrolytes are important in keeping your body functioning correctly.

How Are Electrolytes Controlled?
Your kidneys, lungs, and other glands, including the adrenal glands very tightly control the levels of electrolytes in your body. The adrenal glands, which sit on top of the kidneys and secrete hormones, are especially important in controlling electrolytes. For example, if you eat or drink salty foods, the kidneys will excrete the extra salt to prevent excessive sodium and water from being retained, which could otherwise result in fluid overload and heart failure. Another example is sweating. Sweat is composed of both water and electrolytes (primarily sodium chloride, commonly known as table salt). Your body responds to sweating by changing the way the kidneys filter the blood to regulate the amount of water and electrolytes that are excreted in the urine. This results in the concentrated urine you may excrete if you exercise without consuming enough fluids.

Why Are Electrolytes Important?
All cells maintain an electrical charge across the cell membranes that surround them, which permits cells to perform their normal functions, such as allowing nerve cells to control muscles and allowing muscle cells to contract and relax. The electrolytes in the serum (blood) produce this electrical charge, which is literally the energy of life. If electrolytes exceed their normal, tightly controlled range, normal functions will cease. Muscles may weaken and cramp, nerves may fail to conduct impulses correctly, or the brain (which, after all, is a collection of nerve cells) may not function correctly, leading to confusion, lethargy, or even seizures.

What Conditions Cause Abnormal Electrolytes?
The most common medical conditions that cause electrolyte imbalances are persistent vomiting and diarrhea. In either case, one loses not only fluids, but also significant amounts of electrolytes. Many medications, such as diuretics ("water pills") that are used to treat either high blood pressure or fluid retention, can result in electrolyte problems. Many endocrine diseases, such as diabetes, can also cause electrolyte imbalances. Whatever the etiology, treatment requires replacement of not only the water portion, but also the electrolytes, usually in the form of salty fluids.

Mike Myers, MD, is a family physician in Orange County, CA specializing in weight management and eating disorders for the last 24 years.