Does this test have other names?
Serum potassium, K
What is this test?
This is a blood test to measure the amount of potassium in your blood. Potassium is
one of several important minerals in your body called electrolytes. Ninety percent
of your potassium is inside your cells, but a small amount moves around in your blood.
You normally get potassium from the foods you eat. Your body needs a constant level
of potassium for normal nerve conduction, muscle contraction, heart function, and
fluid balance. Your kidneys remove potassium through your urine.
Why do I need this test?
You may need this test if you are having routine blood test to check your level of
electrolytes. You may also need this test if your healthcare provider suspects that
your potassium is too high or too low. It's important to have your potassium level
checked if you have diabetes, if you have a disease that affects your kidneys, adrenal
glands, or digestive system, or if you are on medicines, such as diuretics, steroids,
A potassium level that is too high is called hyperkalemia. Symptoms of hyperkalemia
Tingling or numbness
Weakness or paralysis
A potassium level that is too low is called hypokalemia. Symptoms of hypokalemia include:
What other tests might I have along with this test?
You may have your potassium checked along with other electrolytes, such as sodium.
You may also have an electrocardiogram, or ECG, to check your heart rhythm. An irregular
heart rhythm is a dangerous sign if caused by an abnormal potassium level.
What do my test results mean?
Test results may vary depending on your age, gender, health history, and other things.
Your test results may be different depending on the lab used. They may not mean you
have a problem. Ask your healthcare provider what your test results mean for you.
Potassium is measured in milliequivalents per liter (mEq/L). Normal results are about:
Low blood potassium may be caused by:
Loss of potassium due to diarrhea, excessive laxative use, sweating, or vomiting
Not getting enough potassium in your diet. This is sometimes seen in alcoholism.
Loss of potassium from a severe burn or draining wound
Diseases, such as cystic fibrosis, primary aldosteronism, or alcoholism
Medicines, such as diuretics or antibiotics
Getting IV fluids without enough potassium
High blood potassium may be caused by:
Kidney disease or kidney failure
Trauma, such as burns, accidents, or surgery
Diseases, such as lupus, sickle cell, or Addison disease
How is this test done?
The test is done with a blood sample. A needle is used to draw blood from a vein in
your arm or hand.
Does this test pose any risks?
Having a blood test with a needle carries some risks. These include bleeding, infection,
bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may
feel a slight sting or pain. Afterward, the site may be sore.
What might affect my test results?
Several medicines can affect your potassium level. These include penicillin, glucose,
diuretics, such as furosemide or hydrochlorothiazide, and nonsteroidal anti-inflammatory
drugs (NSAIDS). Eating a lot of licorice can decrease potassium levels.
How do I get ready for this test?
You don't need to prepare for this test. Tell your healthcare provider if you are
taking any medicine, including over-the-counter NSAIDs. Be sure your healthcare provider
knows about all medicines, herbs, vitamins, and supplements you are taking. This includes
medicines that don't need a prescription and any illegal drugs you may use.