Summary

• Electrolytes are minerals that have an electric charge when dissolved in water.
• In your body, they help regulate many systems including heart rhythms, nerves, and muscles.
• They are also involved in helping maintain the amount of fluid and the acid-base balance in your body.
• The kidneys control electrolyte levels in the blood and the most common cause of electrolyte imbalance is kidney damage.
• Electrolyte tests such as sodium and potassium are used along with other tests to assess how well your kidneys, liver and some steroids and hormones are working.

What are electrolytes?

Cells use electrolytes to transmit electrical impulses internally and externally, to other cells. In this way, the nerves, heart and muscles can create nerve impulses and muscle contractions that contribute to vital body functions such as heart rhythms. The main electrolytes that are tested for are:

• Sodium (salt)
• Potassium 
• Chloride 
• Bicarbonate

Having too much or too little of any of these electrolytes can cause health problems.

The role of your kidneys
Your kidneys work to keep electrolyte levels in the blood at a constant level no matter what changes take place in the body.  They do this through the reabsorption of electrolytes into the blood or by getting rid of them through the urine. The most common cause of electrolyte imbalance is kidney dysfunction.

Electrolyte levels are affected by how much of them is taken in through your diet, the amount of water in your body, and the quantity of electrolytes that are removed by your kidneys and urine. They are also affected by hormones, especially aldosterone, a hormone that keeps sodium in the body but increases the loss of potassium through the kidneys.

Why get tested?

Electrolyte tests are most often ordered:

• As part of a group of tests called the Renal Profile which includes creatinine and urea to check how well your kidneys are working,
• Together with Liver Function Tests, a group of tests to assess your liver, and 
• In response to possible heart problems or diabetes.

Water balance
Between them, sodium and potassium help maintain the body's fluid balance. Under normal conditions the fluid inside and outside your cells is kept in balance.

Acid-base (pH) balance
Changes in acid and alkaline levels in your blood, known as the acid-base balance, can affect electrolyte levels particularly those of potassium and bicarbonate. Electrolyte balance and acid-base balance are closely linked.

Chloride
Chloride travels in and out of the body's cells to help maintain electrical neutrality, and its level usually mirrors that of sodium.

Oxygen, CO₂ and bicarbonate
Your lungs bring oxygen into your body, and it is transferred into the blood and transported to the cells where it is used by your metabolism to generate energy. A by-product of metabolism is the production of CO₂ (carbon dioxide).  This passes from the cells into the blood and is transported as bicarbonate to your lungs where it is exhaled as carbon dioxide. Bicarbonate concentrations are adjusted by the kidneys to help maintain stable pH levels and maintain electrical neutrality.

Having the test

Sample

Blood.

Any preparation?

None.

Your results

Reading your test report

Your results will be presented along with those of your other tests on the same form.  You will see separate columns or lines for each of these tests.

In specific disorders, one or more electrolytes may be abnormal. Your doctor will look at the overall balance, but they are likely to be especially concerned with your sodium and potassium levels.

If your kidneys are not functioning properly, you can retain too much fluid. This dilutes sodium and chloride so that they fall below normal levels.

If you experience severe fluid loss (dehydration), you may show an increase in potassium, sodium, and chloride levels.

Some forms of heart disease, muscle, nerve problems and diabetes can also cause one or more abnormal electrolyte levels.

Some medications can change electrolyte levels.

Knowing which electrolytes are out of balance can help your doctor determine the cause and treatment to restore proper balance.

Reference Intervals

Your results will be compared to a reference interval (sometimes called a normal range or reference range).

• Reference intervals are the range of results expected in healthy people. 
• When compared against them your results may be flagged high or low if they sit outside this range.
• Many reference intervals vary between laboratories so only those that are standardised or harmonised across most laboratories are given on this website.

If your results are flagged as high or low this does not necessarily mean that anything is wrong. It depends on your personal situation. Your results need to be interpreted by your doctor.

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms. It is important that you tell them everything you think might help.
You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.
Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:

• Why does this test need to be done?
• Do I need to prepare (such as fast or avoid medications) for the sample collection?
• Will an abnormal result mean I need further tests?
• How could it change the course of my care?
• What will happen next, after the test?

More information

Pathology and diagnostic imaging reports can be added to your My Health Record.

You and your healthcare provider can now access your results whenever and wherever needed. Get further trustworthy health information and advice from healthdirect.