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Serum/plasma concentration of potassium (K⁺) measured by ion-selective electrode

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of potassium, a vital mineral, in your blood. Potassium helps regulate important bodily functions, including muscle and nerve activity.

Quick summary

["Potassium levels can affect heart rhythm and muscle function."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
73018-4
Short code
Furosemide (neut) IgG SerPl Ql FC
Synonyms
Furosemide (neut) IgG SerPl Ql FC
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to check for low (hypokalemia) or high (hyperkalemia) potassium levels, which can occur due to conditions like kidney disease, heart problems, or certain medications. It may also be part of routine blood work or monitoring for conditions affecting electrolyte balance.

What to Expect Before the Test

No special preparation is needed. You may eat and drink normally before the test. If you’re on certain medications (like diuretics), let your provider know, as they might affect your potassium levels.

How the Test Is Performed

A blood sample is taken from a vein, usually in your arm. The blood is sent to a lab where it’s analyzed for potassium concentration using an ion-selective electrode method.

What the Results Mean

Results are compared to standard reference ranges, but exact values can vary by lab. Low potassium may cause muscle weakness or irregular heartbeat, while high potassium can lead to heart rhythm disturbances. Your provider will interpret results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Potassium is essential for nerve and muscle function, including heart contractions. Imbalances can cause serious complications like arrhythmias, muscle cramps, or even heart failure. Regular monitoring helps prevent or manage conditions like kidney disease, diabetes, or certain medications that alter potassium levels.

Short name

Serum potassium (K⁺) level

Frequently asked questions

How long does it take to get my potassium test results?
Results are typically available within 1–2 business days, depending on your lab. Your provider will contact you with the final report, so check in with them if you haven’t heard back sooner.
Can I eat or drink anything before my potassium test?
Yes, you can eat and drink normally. Avoid excessive salt or potassium-rich foods (like bananas or spinach) if your provider advised it, but this is rare unless you have specific instructions.
What causes low potassium levels?
Low potassium (hypokalemia) can result from conditions like vomiting, diarrhea, excessive sweating, or certain medications (e.g., diuretics). It can also occur if your kidneys aren’t filtering potassium properly or if you have severe dehydration.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy