A patient seated in the chair before a blood draw
In person

Potassium

The electrolyte behind muscle, nerve, and heart rhythm, from one draw.

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  • 2,000+ lab locations. Find one near you
  • Nothing due at the lab. FSA / HSA accepted
  • Ordered by a licensed clinician

At a glance

Collection
Blood draw
A standard blood draw at the lab.
Preparation
None
Nothing to do ahead of time. Water is fine.
Results
1 to 2 days
Typical turnaround after your visit.
Where
2,000+ lab locations
Nationwide, with nothing due at the lab.

About this test

Potassium is an electrolyte your muscles and nerves need to work, including the muscle of your heart. The kidneys keep it in a narrow range, and some medicines and conditions can push it up or down. It is often checked with other electrolytes during medication check-ins. No fasting is needed.

For adults 18 and older. Test availability varies by lab location.

Who should take this test?

This test is for adults whose healthcare provider wants to check potassium, often while they take certain blood pressure medicines or diuretics, or to follow a past result.

Ask about this test

Not sure this is the right test?

AI-generated. For information only, not medical advice. Call 911 for an emergency.

What does this test measure?

Your result shows how much potassium is in your blood, which can help a healthcare provider check your electrolyte balance and follow the effect of some medicines.

Potassium
Potassium is an electrolyte that your nerves and muscles, including your heart, need to work properly. Your kidneys keep the level in a narrow range. It can be affected by kidney function, some medicines such as diuretics, and how the sample is handled, so it is read with other results.
Why it’s measured: Muscles and the heart depend on potassium staying in a narrow range.

How it works

  1. Step 1

    Order online

    Check out here. A licensed clinician in your state reviews your order and sends it to the lab.

  2. Step 2

    Visit a lab

    Bring a photo ID to any of 2,000+ lab locations. No fasting needed, and nothing is due at the lab.

  3. Step 3

    Get your results

    Results post to your account, usually in 1 to 2 days, each number next to the lab’s reference range.

Find a lab near you

Choose from 2,000+ lab locations nationwide. Your order works at any of them.

What your results tell you

Potassium is reported in millimoles per liter (mmol/L) and compared with the lab’s reference range, which is shown on your report.

  • Your number next to the lab’s reference range
  • Explained in plain language
  • A licensed clinician reviews your order and, if appropriate, orders the test.
  • A lab report you can download and share

An out-of-range potassium result can need prompt follow-up with a healthcare provider, who can explain what it means for you.

Clinical-grade testing, from the comfort of home.

From the lab to your report, every step of our process meets the gold standard in medical testing.

  • CLIA-certified labs

    Every lab we partner with is certified under the Clinical Laboratory Improvement Amendments, meeting both state and federal standards with regular independent inspections.

  • We protect your health data

    We protect your health data with encryption and do not sell it. Some results must be reported to public health authorities by law. See our Privacy Notice.

  • Rigorous quality assurance

    All partner labs run regular internal quality checks, participate in proficiency testing, and comply with federal and state lab regulations.

  • Clinician-reviewed reports

    Results are reviewed by an independent, licensed clinician.

Questions

Common questions.

Anything else, our care team answers by phone, text, or email.

Some medicines change how the kidneys handle potassium. Diuretics, sometimes called water pills, can lower potassium, and other medicines can affect it too. That is why potassium is often checked during medication check-⁠ins.

Don’t stop or change any medicine or supplement without talking with your healthcare provider.

Red blood cells hold a lot of potassium. If some cells break open during or after the draw, or the sample waits too long before it is processed, potassium can leak out and make the result read higher than your true level. An unexpected result is often rechecked for this reason.

No. This test is not for emergencies. If you have chest pain, a racing or irregular heartbeat, fainting, severe weakness, or sudden confusion, get emergency care right away rather than waiting for a lab visit or a result.

A potassium result shows your level at the time of the draw, not why it is high or low. Causes range from medicines to kidney or hormone changes. A healthcare provider reads it with your other results, medicines, and history.

Lab tests are informational and don’t diagnose conditions on their own. Available to adults 18 and older; test availability varies by lab location. A licensed clinician reviews your order and, if appropriate, orders the test. All testing is performed at CLIA-certified laboratories. Not for emergencies: if you think you may be having a medical emergency, call 911.