What are normal potassium levels?

Tzvi Doron, DO - Contributor Avatar

Reviewed by Tzvi Doron, DO, 

Tzvi Doron, DO - Contributor Avatar

Reviewed by Tzvi Doron, DO, 

last updated: May 04, 2020

1 min read

Here's what we'll cover

  1. What we mean by normal

Normal potassium levels in the blood are 3.7–5.2 mmol/L.

Potassium is an important electrolyte in the body that plays a role in many functions. Having a potassium level that is too low (hypokalemia) and having a potassium level that is too high (hyperkalemia) are both very dangerous and can lead to weakness, muscle cramping, and death.

High potassium, in particular, can cause heart rhythm problems that are fatal. Potassium levels are regulated by the kidneys and can be affected by certain medical conditions (such as kidney disease) or by taking certain medications (such as diuretics). Potassium levels can be raised with oral or injectable potassium; potassium levels can be lowered with a variety of medications.

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What we mean by normal

In medicine, using the term “normal” can sometimes be off-putting. Saying something is “normal” implies that everything else is “abnormal.” Additionally, saying something is “normal” may not be accurate, since something that is “normal” for you may not be “normal” for somebody else. Therefore, instead of saying certain values are “normal,” alternative terminology may be to say that these values are “healthy” or “within the reference range.”

Additionally, some values have well-defined cutoffs, while others do not. For example, when looking at hemoglobin A1c levels, a value of 6.5 or greater is always diagnostic of diabetes. On the other hand, when looking at testosterone levels, some use cutoffs of 270–1,070 ng/dL while others use cutoffs of 300–1,000 ng/dL.

The information above represents values that are commonly used as cutoffs. However, depending on the specific source you’re looking at or the laboratory you go to, their values may be a little different.


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

May 04, 2020

Written by

Mike Bohl, MD, MPH, ALM

Fact checked by

Tzvi Doron, DO

About the medical reviewer

Dr. Tzvi Doron is Board Certified in Family Medicine by the American Board of Family Medicine.