Potassium (Serum or Plasma) Concentration
This test measures the amount of potassium, a vital mineral electrolyte, in your blood. Potassium helps regulate heart rhythm, muscle function, and fluid balance.
["Potassium helps maintain heart health and muscle function; abnormal levels may signal serious health concerns."]
Key facts at a glance
- LOINC
- 93998-3
- Short code
- Potassium 1h p Vaso SerPl-sCnc
- Synonyms
- Potassium 1h p Vaso SerPl-sCnc
- 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 like low or high potassium levels, which can affect heart function, muscle weakness, or other health issues. It’s often done if you have symptoms such as muscle cramps, irregular heartbeat, or signs of kidney problems.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic panel, but this isn’t always required. Bring any medications you’re taking to your appointment.
How the Test Is Performed
A healthcare provider will draw blood from a vein in your arm using a small needle. The blood sample is sent to a lab for analysis. The test measures potassium concentration in your serum or plasma.
What the Results Mean
Results are reported as a concentration value (typically in milliequivalents per liter, mEq/L). While reference ranges vary by lab, low potassium (hypokalemia) or high potassium (hyperkalemia) may indicate underlying health issues that need medical attention.
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.
◆Associated findings1
Short name
Potassium Level
Frequently asked questions
Low potassium levels can cause muscle weakness, irregular heartbeat, or fatigue. High potassium levels may lead to heart rhythm disturbances, nausea, or weakness. Both conditions require prompt medical evaluation and treatment.
Results are usually available within 1–3 business days, depending on your lab and testing schedule. Your doctor will discuss the findings with you during your follow-up visit.
What if my potassium level is out of range?
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