Hypokalemia test; Hyperkalemia test; K+
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.
You may have this test to diagnose or monitor kidney disease. The most common cause of a high blood potassium level is kidney disease.
Potassium is important to heart function.
It may also be done if your provider suspects metabolic acidosis (for example, caused by uncontrolled diabetes) or alkalosis (for example, caused by excess vomiting).
Sometimes, the potassium test may be done in people who are having an attack of paralysis.
The normal range is 3.7 to 5.2 milliequivalents per liter (mEq/L) 3.70 to 5.20 millimoles per liter (millimol/L).
Normal value ranges may vary slightly among different laboratories. Talk to your provider 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.
Mount DB. Disorders of potassium balance. In: Yu ASL, Chertow GM, Luyckx VA, Marsden PA, Skorecki K, Taal MW, eds. Brenner and Rector's The Kidney. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 17.
Patney V, Whaley-Connell A. Hypokalemia and hyperkalemia. In: Lerma EV, Sparks MA, Topf JM, eds. Nephrology Secrets. 4th ed. Philadelphia, PA: Elsevier; 2019:chap 74.
Seifter JL. Potassium disorders. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 109.BACK TO TOP
Review Date: 5/1/2021
Reviewed 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 David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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