Potassium concentration in serum/plasma
This test measures the amount of potassium, a mineral essential for heart function, muscle contractions, and nerve signaling, in your blood.
["Potassium helps regulate fluid balance and supports normal heart rhythms."]
Key facts at a glance
- LOINC
- 42569-4
- Short code
- Potassium SerPl-msCnc
- Synonyms
- Potassium SerPl-msCnc
- Category
- electrolyte
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 3.5
- Ref high
- 5
- Critical range
- 2.5 N/A – 6.5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84132
- SNOMED
- 110742001
- 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 levels, such as kidney problems, heart issues, or certain medications that alter potassium balance. It can also help monitor long-term health or diagnose symptoms like muscle weakness, irregular heartbeat, or nausea.
What to Expect Before the Test
No special preparation is needed, but avoid eating or drinking for at least 8–12 hours before the test if instructed. If you’re on certain medications (like diuretics or heart medications), let your doctor know beforehand.
What Happens During the Test?
A healthcare provider will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood sample is then sent to a lab for analysis.
What Do Results Mean?
Results show your potassium level compared to a standard range. Low potassium (hypokalemia) or high potassium (hyperkalemia) can signal underlying health concerns, but interpretation depends on your overall health and other test results.
Reference range
Adult: 3.5-5.0 mmol/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Potassium is critical for electrical activity in your heart and muscles. Abnormally low or high levels can cause serious complications, including irregular heartbeats, muscle cramps, or even life-threatening conditions. Your doctor will use this test alongside other factors to guide treatment if needed.
Short name
Serum Potassium (K+)
Frequently asked questions
How long does it take to get results?
Can diet affect potassium test results?
What symptoms might indicate low or high potassium?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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