Blood-tests Explained


Disclaimer:

This website is intended to assist with patient education and should not be used as a diagnostic, treatment or prescription service, forum or platform. Always consult your own healthcare practitioner for a more personalised and detailed opinion

Electrolytes


At a Glance

Why Get Tested?

To detect a problem with the body's electrolyte balance

When to Get Tested?

As part of routine health screening or when your healthcare provider suspects that you have an imbalance of one of the electrolytes (usually sodium or potassium) or an acid-base imbalance

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

The Test Sample

What is being tested?

Electrolytes are minerals that are found in body tissues and blood in the form of dissolved salts. As electrically charged particles, electrolytes help move nutrients into and wastes out of the body's cells, maintain a healthy water balance, and help stabilize the body's acid/base (pH) level.

The electrolyte panel measures the blood levels of the main electrolytes in the body: sodium (Na+), potassium (K+), chloride (Cl-), and bicarbonate (HCO3-; sometimes reported as total CO2).

A person's diet provides sodium, potassium, and chloride. The kidneys help maintain proper levels by reabsorption or by elimination into the urine. The lungs provide oxygen and regulate CO2. The CO2 is produced by the body and is in balance with bicarbonate. The overall balance of these chemicals is an indication of the functional well-being of several basic body functions. They are important in maintaining a wide range of body functions, including cardiac and skeletal muscle contraction and nerve impulse conduction.

Any disease or condition that affects the amount of fluid in the body, such as dehydration, or affects the lungs, kidneys, metabolism, or breathing has the potential to cause a fluid, electrolyte, or pH imbalance (acidosis or alkalosis). Normal pH must be maintained within a narrow range of 7.35-7.45 and electrolytes must be in balance to ensure the proper functioning of metabolic processes and the delivery of the right amount of oxygen to tissues. (For more on this, see the condition article on Acidosis and Alkalosis and also on Dehydration.)

A related "test" is the anion gap, which is a value calculated using the results of an electrolyte panel. It reflects the difference between the positively charged ions (called cations) and the negatively charged ions (called anions). An abnormal anion gap is non-specific but can suggest certain kinds of metabolic or respiratory disorders or the presence of toxic substances. For more information on anion gap, see Common Questions #1.

How is the sample collected for testing?

A blood sample is drawn by needle from a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test