Serum Electrolytes

Why test for Serum Electrolytes

Electrolytes are minerals in your blood and other body fluids that carry an electric charge.

Electrolytes affect how your body functions in many ways, including:

• The amount of water in your body
• The acidity of your blood (pH)
• Your muscle function
• Other important processes
• You lose electrolytes when you sweat. You must replace them by drinking fluids that contain electrolytes. Water does not contain electrolytes.

The electrolyte panel is used to identify an electrolyte, fluid, or pH imbalance (acidosis or alkalosis). It is frequently ordered as part of a routine physical. It may be ordered by itself or as a component of a basic metabolic panel (BMP) or a comprehensive metabolic panel (CMP). These panels can include other tests such as BUN, creatinine, and glucose.

Electrolyte measurements may be used to help investigate conditions that cause electrolyte imbalances such as dehydration, kidney disease, lung diseases, or heart conditions. Repeat testing may then also be used to monitor treatment of the condition causing the imbalance.

Since electrolyte and acid-base imbalances can be present with a wide variety of acute and chronic illnesses, the electrolyte panel is frequently used to evaluate patients both in the emergency room as well as hospitalized patients.

The electrolyte panel typically includes tests for:

Sodium—most of the body's sodium is found in extracellular fluid, outside of the body's cells, where it helps to regulate the amount of water in the body.

Potassium—this electrolyte is found mainly inside the body's cells. A small but vital amount of potassium is found in the plasma, the liquid portion of the blood. Monitoring potassium is important as small changes in the potassium level can affect the heart's rhythm and ability to contract.

Chloride—this electrolyte moves in and out of the cells to help maintain electrical neutrality and its level usually mirrors that of sodium.

The results for an electrolyte panel may also include a calculation for anion gap.

If a person has an imbalance of a single electrolyte, such as sodium or potassium, the health practitioner may order repeat testing of that individual electrolyte, monitoring the imbalance until it resolves. If someone has an acid-base imbalance, the health practitioner may also order tests for blood gases, which measure the pH and oxygen and carbon dioxide levels in an arterial blood sample, to help evaluate the severity of the imbalance and monitor its response to treatment.