Potassium test

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Blood test

Hypokalemia test; K+

Risks associated with venipuncture are slight:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)
• Multiple punctures to locate veins

The following factors can interfere with the test:

• Infusion of potassium-containing fluids
• Infusion of glucose or insulin

Drugs that can increase potassium measurements include aminocaproic acid, antineoplastic drugs, ACE inhibitors (such as captopril or enalapril) epinephrine, heparin, histamine, isoniazid, mannitol, some diuretics, and succinylcholine.

Drugs that can decrease potassium measurements include acetazolamide, aminosalicylic acid, amphotericin B, carbenicillin, cisplatin, some diuretics, insulin, laxatives, penicillin G, phenothiazines, salicylates, and sodium polystyrene sulfonate.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others. If puncturing the vein is difficult, trauma to the red blood cells may cause potassium to be released from them, causing a falsely elevated result.

Review Date: 06/13/2005
Reviewed By: Nader Najafian, M.D., Associate Physician, Renal Division, Brigham & Women's Hospital, Instructor of Medicine, Harvard Medical School, Boston, MA. Review provided by VeriMed Healthcare Network.