Patient education: Potassium test (The Basics)

What is a potassium test? — A potassium test is a type of blood test. It measures the amount of potassium in the body.

Potassium is one of many substances in the body called "electrolytes." Potassium helps the heart and other muscles work properly.

Having too much or too little potassium can mean that you have a health problem.

Potassium might be measured as part of other blood tests, such as an "electrolyte panel" or "basic metabolic panel." These tests measure the amount of potassium, plus other substances, in the blood.

Why might I get a potassium test? — Your doctor might want you to get a potassium test:

●If you have symptoms of too much potassium – These include having an irregular heart rhythm, feeling tired and weak, nausea, and paralysis in your arms and legs. (Paralysis is when you cannot move.)

●If you have symptoms of too little potassium – These include an irregular heart rhythm, muscle cramps or twitches, feeling tired and weak, nausea, constipation, or paralysis in your arms and legs.

●As part of another type of test, like an electrolyte panel or basic metabolic panel – These might be done to check if you have an electrolyte or fluid imbalance.

●Because you have another health condition that can affect your potassium level – These include diabetes and chronic kidney disease.

●Because you are taking another medicine that can cause high or low potassium levels

How do I prepare for a potassium test? — For this test, you need to get a "blood draw." Your doctor or nurse will tell you where to go for this.

It might help to wear a short-sleeve shirt to your blood draw appointment. This makes it easier for the person drawing the blood to get to your arm.

What happens during a blood draw? — For the blood draw, a needle is used to take a small amount of blood from your arm (figure 1). Collecting the blood only takes a few minutes. The blood is then tested in a lab.

Tell the person who takes your blood:

●If you take "blood thinner" medicines or if you have a bleeding problem – They will make sure that your bleeding is under control before you leave.

●If you have a latex allergy – Some of the supplies used for blood draws might contain latex.

●If you have a preferred arm to use

Most of the time, getting blood taken does not cause problems. You might have a little soreness or bruising where the needle went in.

What do my results mean? — Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or if you use an online "patient portal," you might get an alert there when your results are ready.

If your potassium test shows any abnormal results, your doctor or nurse will talk to you about what to do next. They might need to do more tests to figure out what the cause is.

If you do have a health problem, your doctor will work with you to come up with a plan for treatment.

More on this topic

Patient education: Electrolyte panel (The Basics)
Patient education: Basic metabolic panel (The Basics)