This test measures the amount of potassium in the fluid portion (serum) of the blood. Potassium (K+) helps nerves and muscles communicate. It also helps move nutrients into cells and waste products out of cells.
Potassium levels in the body are mainly controlled by the hormone aldosterone.
A blood sample is needed. Most of the time blood is drawn from a vein located on the inside of the elbow or the back of the hand.
Many medicines can interfere with blood test results.
You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.
This test is a regular part of a basic or comprehensive metabolic panel.
Your doctor may order this test to diagnose or monitor kidney disease. The most common cause of high potassium levels is kidney disease.
Potassium is important to heart function.
Sometimes, the potassium test may be done in persons who are having an attack of paralysis.
The normal range is 3.7 to 5.2 mEq/L.
Note: mEq/L = milliequivalent per liter
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
High levels of potassium (hyperkalemia) may be due to:
Low levels of potassium (hypokalemia) may be due to:
If it is hard to get the needle into the vein to take the blood sample, injury to the red blood cells may cause potassium to be released. This may cause a falsely high result.
Hypokalemia test; K+
Seifter JR. Potassium disorders. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 119.
Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.
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