A potassium blood test measures the amount of potassium in your blood. Potassium is a type of electrolyte. Electrolytes are electrically charged minerals in your body that help control muscle and nerve activity, maintain fluid levels, and perform other important functions. Your body needs potassium to help your heart and muscles work properly. Potassium levels that are too high or too low may indicate a medical problem.

Other names: potassium serum, serum potassium, serum electrolytes, k

Your health care provider may order a potassium blood test as part of your regular checkup or to monitor an existing condition such as diabetes or kidney disease. You may also need this test if you have symptoms of having too much or too little potassium.

If your potassium levels are too high, your symptoms may include:

• Irregular heart rhythms
• Fatigue
• Weakness
• Nausea
• Paralysis in the arms and legs

If your potassium levels are too low, your symptoms may include:

• Irregular heart rhythms
• Muscle cramps
• Twitches
• Weakness
• Fatigue
• Nausea
• Constipation

Too much potassium in the blood, a condition known as hyperkalemia, may indicate:

• Kidney disease
• Burns or other traumatic injuries
• Addison's disease, a hormonal disorder that can cause a variety of symptoms including weakness, dizziness, weight loss, and dehydration
• Type 1 diabetes
• The effect of medicines, such as diuretics or antibiotics
• In a rare instances, a diet too high in potassium. Potassium is found in many foods, such as bananas, apricots, and avocados, and is part of a healthy diet. But eating excessive amounts of potassium-rich foods can lead to health problems.

Too little potassium in the blood, a condition known as hypokalemia, may indicate:

• A diet too low in potassium
• Alcoholism
• Loss of bodily fluids from diarrhea, vomiting, or use of diuretics
• Aldosteronism, a hormonal disorder that causes high blood pressure

If your results are not in the normal range, it doesn't necessarily mean that you have a medical condition requiring treatment. Certain prescription and over-the-counter medicines may raise your potassium levels, while eating a lot of licorice may lower your levels. To learn what your results mean, talk to your health care provider.

1. Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Potassium, Serum; 426–27 p.
2. Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Potassium [updated 2016 Jan 29; cited 2017 Feb 8]; [about 2 screens]. Available from: https://labtestsonline.org/understanding/analytes/potassium/tab/test
3. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2017. High potassium (hyperkalemia); 2014 Nov 25 [cited 2017 Feb 8]; [about 4 screens]. Available from: http://www.mayoclinic.org/symptoms/hyperkalemia/basics/when-to-see-doctor/sym-20050776
4. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2017. Low potassium (hypokalemia); 2014 Jul 8 [cited 2017 Feb 8]; [about 4 screens]. Available from: http://www.mayoclinic.org/symptoms/low-potassium/basics/when-to-see-doctor/sym-20050632
5. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2017. Primary aldosteronism; 2016 Nov 2 [cited 2017 Feb 8]; [about 3 screens]. Available from: http://www.mayoclinic.org/diseases-conditions/primary-aldosteronism/home/ovc-20262038
6. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co., Inc.; c2016. Addison Disease (Addison's Disease; Primary or Chronic Adrenocortical Insufficiency) [cited 2017 Feb 8]; [about 3 screens]. Available from: https://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/adrenal-gland-disorders/addison-disease
7. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co., Inc.; c2016. Hyperkalemia (High Level of Potassium in the Blood) [cited 2017 Feb 8]; [about 3 screens]. Available from: http://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/hyperkalemia-high-level-of-potassium-in-the-blood
8. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co., Inc.; c2016. Hypokalemia (Low Level of Potassium in the Blood) [cited 2017 Feb 8]; [about 3 screens]. Available from: http://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/hypokalemia-low-level-of-potassium-in-the-blood
9. Merck Manual Consumer Version [Internet]. Kenilworth (NJ Merck & Co., Inc.; c2016. Overview of Potassium's Role in the Body [cited 2017 Feb 8]; [about 3 screens]. Available from: http://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/overview-of-potassium-s-role-in-the-body
10. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; What Are the Risks of Blood Tests? [updated 2012 Jan 6; cited 2017 Feb 8]; [about 4 screens]. Available from: https://www.nhlbi.nih.gov/health/health-topics/topics/bdt/risks