A potassium test measures the amount of potassium in blood serum (the fluid part of your blood).

Potassium is a mineral that helps:

  • nerves and muscles "communicate"
  • nutrients move into cells and waste products move out of cells
  • the heart function healthily

A potassium test may be recommended to help diagnose or monitor kidney disease, which is the most common cause of high potassium levels.

Your doctor may also recommend the test if you have heart-related problems, such as high blood pressure (hypertension).

If you have low potassium levels, you may have a heart problem, such as an irregular heartbeat. If you have high potassium levels, your heart muscle activity may be reduced. Both situations are serious and can be life-threatening.

You may also have a potassium test if you have diabetes and your doctor thinks you may have diabetic ketoacidosis (a complication caused by a lack of insulin in the body).

In rare cases, potassium levels may be low through poor diet. Good sources of dietary potassium include:

  • fruit, particularly bananas
  • vegetables
  • pulses
  • nuts and seeds
  • milk
  • fish
  • shellfish
  • beef
  • chicken
  • turkey
  • bread

Read more about the potassium test at Lab Tests Online UK.

Page last reviewed: 02/10/2015

Next review due: 02/10/2017