potassium test checks how much potassium is in the blood. Potassium is both an
electrolyte and a mineral. It helps keep the water
(the amount of fluid inside and outside the body's cells) and electrolyte
balance of the body. Potassium is also important in how nerves and muscles
Potassium levels often change with sodium levels. When
sodium levels go up, potassium levels go down, and when sodium levels go down,
potassium levels go up. Potassium levels are also affected by a hormone called
aldosterone, which is made by the
Potassium levels can be
affected by how the
kidneys are working, the blood pH, the amount of potassium you eat, the
hormone levels in your body, severe vomiting, and
taking certain medicines, including potassium supplements. Certain cancer
treatments that destroy cancer cells can also make potassium levels
Many foods are rich in potassium, including scallops,
potatoes, figs, bananas, prune juice, orange juice, and squash. A balanced diet
has enough potassium for the body's needs. But potassium is passed in the urine
even if the level in the blood is low so the level of potassium in the body can
A potassium level that is too high or too low can be
serious. Abnormal potassium levels may cause symptoms such as muscle cramps or
weakness, nausea, diarrhea, frequent urination,
dehydration, low blood pressure, confusion,
irritability, paralysis, and changes in heart rhythm.
electrolytes, such as sodium, calcium, chloride, magnesium, and phosphate, may
be checked in a blood sample at the same time as a blood test for
Why It Is Done
A blood test to check
potassium is done to:
- Check levels in people being treated with
medicines such as
diuretics and for people having
- Check to see whether
treatment for too low or too high potassium levels is
- Check people with
high blood pressure who may have a problem with their
kidneys or adrenal glands.
- Check the effects of extra nutrition
(total parenteral nutrition [TPN]) on potassium
- Check to see whether certain cancer treatments are causing
too many cells to be destroyed (cell lysis). Cell lysis syndrome causes very
high levels of some electrolytes, including potassium.
How To Prepare
You do not need to do anything before
having this test.
Talk to your doctor about any
concerns you have regarding the need for the test, its risks, how it will be
done, or what the results will mean. To help you understand the importance of
this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
The health professional drawing blood
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure to the site and then a