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Potassium (Serum) Concentration

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

This test measures the amount of potassium, a mineral essential for heart function and nerve signaling, in your blood serum.

Quick summary

["Potassium levels help ensure your heart beats steadily and your muscles work properly."]

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

Key facts at a glance

LOINC
667-6
Short code
KOH Prep Spec
Synonyms
KOH Prep Spec
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
koh-preparation
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 doctor may order this test to check for conditions affecting potassium balance, such as kidney problems, heart issues, or certain medications that alter potassium levels. It’s also used to monitor treatment progress or diagnose symptoms like muscle weakness, irregular heartbeat, or nausea.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on certain medications (like diuretics), your doctor may advise adjusting timing or hydration to avoid temporary changes in results.

What the Results Mean

Results are compared to a general reference range, but individual ranges can vary by lab. Low potassium (hypokalemia) may cause muscle cramps or fatigue, while high potassium (hyperkalemia) could affect heart rhythm. Your doctor will interpret results in the context of your overall health.

Common Causes of Abnormal Results

Low potassium can result from excessive vomiting, diarrhea, or certain medications, while kidney problems, untreated diabetes, or severe dehydration may raise potassium levels. Chronic conditions like heart failure or Addison’s disease can also influence results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Potassium

Frequently asked questions

Why might my potassium test be done more frequently than other blood tests?
If you have ongoing health conditions like kidney disease, heart problems, or are taking medications that affect potassium (e.g., diuretics, ACE inhibitors), your doctor may monitor potassium levels regularly to adjust treatment and prevent dangerous imbalances.
Can food or drinks affect my potassium test results?
While diet can influence potassium levels in your body, the blood test itself measures serum potassium at the time of drawing. However, if you’re fasting, avoid high-potassium foods (e.g., bananas, spinach) for 12–24 hours before testing to reduce variability.
What should I do if I notice symptoms like muscle twitching or irregular heartbeat before my test?
Contact your doctor immediately. Symptoms like these could signal an urgent potassium imbalance. They may need to adjust your treatment, monitor you closely, or perform additional tests to determine the cause.
  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