Potassium concentration in serum/plasma
This test measures the amount of potassium, a vital mineral, in your blood. Potassium helps regulate your heart’s rhythm, muscle function, and fluid balance.
["Potassium levels can affect heart health and muscle function; abnormal results may signal underlying health concerns."]
Key facts at a glance
- LOINC
- 15202-5
- Short code
- Potassium Stl-sCnc
- Synonyms
- Potassium Stl-sCnc
- Category
- electrolyte
- Sample
- stool
- Container
- Clean container
- 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 g
- Stability
- Refrigerated: 24h, Frozen: 7d
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order this test to check for conditions like low potassium (hypokalemia) or high potassium (hyperkalemia), which can cause weakness, irregular heartbeat, or other symptoms. It’s often done if you have symptoms like muscle cramps, fatigue, or irregular heartbeat, or if you’re taking certain medications that affect potassium levels.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for a few hours before the blood draw if your doctor specifies it. Wear comfortable clothing and plan to sit or lie down during the procedure.
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 pain. The blood sample is then sent to a lab for analysis.
What Are Common Results?
Results are typically reported as a numerical value (in mmol/L or mEq/L) representing your potassium concentration. Your doctor will interpret these results in relation to your overall health and symptoms.
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.
Low potassium levels (hypokalemia) can weaken muscles, cause irregular heartbeats, or lead to fatigue. High potassium levels (hyperkalemia) may also disrupt heart rhythm, especially in people with kidney problems or certain medical conditions. Your doctor will assess results alongside your medical history and other test results to determine if treatment is needed.
Short name
Serum Potassium (K⁺)
Frequently asked questions
What causes potassium levels to be too low?
What causes potassium levels to be too high?
How long does it take to get results?
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