Potassium Blood Test
Reviewed
Also called: potassium serum, serum potassium, serum electrolytes, K
A potassium blood test measures the amount of potassium in your blood. Potassium is a type of electrolyte.
Specimen: Blood sample (serum)
Why this test may be ordered
- As part of a routine checkup
- To monitor an existing condition such as diabetes, kidney disease, or adrenal gland disorders
- If you take medicines that could affect potassium levels
- If you have symptoms of too much potassium (hyperkalemia) including arrhythmia, fatigue, muscle weakness, nausea, numbness or tingling
- If you have symptoms of too little potassium (hypokalemia) including irregular heartbeat, muscle cramps, weak or twitching muscles, fatigue, nausea, constipation
Preparation and collection
You don't need any special preparations for a potassium blood test or an electrolyte panel. Your provider will let you know if there are any special instructions to follow.
A health care professional will take a blood sample from a vein in your arm, using a small needle. This usually takes less than five minutes.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
Potassium levels that are too high or too low may be a sign of a medical condition and may cause serious health issues.
What does high potassium (hyperkalemia) mean?
High potassium level (hyperkalemia): Too much potassium in the blood (hyperkalemia) is often the result of two or more causes, which could include: kidney disease. Limitation: Repeated clenching and relaxing of your fist just before or during your blood test may temporarily increase the potassium levels in your blood. This may lead to an incorrect result. Next step: To learn what your results mean, talk with your provider.- Low potassium level (hypokalemia): Too little potassium in the blood (hypokalemia) may be a sign of: the side effects of prescription diuretics, fluid loss from diarrhea, vomiting, or heavy sweating, using too many laxatives. Limitation: You should not eat natural black licorice for at least two weeks before your test because it may lower your levels. Next step: To learn what your results mean, talk with your provider.
- Repeated clenching and relaxing of your fist just before or during the blood draw may temporarily increase potassium levels and lead to an incorrect result.
- Eating natural black licorice (not common in the U.S.) within two weeks before the test may lower potassium levels.
- Certain prescription and over-the-counter medicines and supplements can affect potassium levels.
What to do next
To learn what your results mean, talk with your provider.
- What is a potassium blood test?
- Why do I need a potassium blood test?
- What happens during a potassium blood test?
- Will I need to do anything to prepare for the test?
- Are there any risks to the test? What do the results mean?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.