Boots WebMD Partners in Health
Return To Boots

Testing sodium, potassium and more

An electrolyte test is used to identify problems with the body's electrolyte ( salt) balance.

Electrolytes are minerals that are found in body tissues and blood in the form of dissolved salts. They help to move nutrients into cells in the body and move waste products out of them. Electrolytes also maintain a healthy water balance and help stabilise the body's acid/base (pH) level.

The main electrolytes in the body are potassium and sodium. Other electrolytes are chloride and bicarbonate.

Potassium is found mainly inside the body's cells. Small amounts are also found in blood plasma. It has an important role in regulating the heart's rhythm and ability to contract.

Sodium is mainly found outside cells where it helps regulate the amount of water in the body.

Why is electrolyte testing carried out?

Electrolyte testing may be carried out as part of routine blood tests, called U+Es.

You may be tested if your GP thinks you have an imbalance of one of the electrolytes (usually sodium or potassium), or if an acid-base (pH) imbalance is suspected.

The test is useful in evaluating cases where kidney disease, high blood pressure or heart failure is suspected and in monitoring the effectiveness of treatment.

Electrolytes may also be checked if you are prescribed certain medication, particularly diuretics or ACE inhibitors (used to treat high blood pressure and heart failure).

How is electrolyte testing carried out?

A blood sample is taken from a vein in the arm.

WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on February 24, 2017

Stay informed

Sign up for BootsWebMD's free newsletters.
Sign Up Now!

Popular slideshows & tools on BootsWebMD

woman_holding_head_in_pain
How to help headache pain
man in mirror
How smoking affects your looks & life
man holding sore neck
16 tips when you have a lot of weight to lose
man holding sore neck
Could you have a hormone imbalance?
woman looking at pregnancy test
Is your body ready for pregnancy?
man holding sore neck
8 signs you're headed for menopause
couple makigh salad
Nutrition for over 50s
bain illustration
Best foods for your brain
adult man contemplating
When illness makes it hard to eat
Allergies
Allergy myths and facts
egg in cup
Surprising things that can harm your liver