Sodium concentration in blood (serum/plasma)
This test measures the amount of sodium, a key mineral, in your blood. Sodium helps balance fluids and maintain proper heart and muscle function.
["Sodium levels help doctors check for dehydration, kidney issues, or other health concerns."]
Key facts at a glance
- LOINC
- 39791-9
- Short code
- Sodium BldV-sCnc
- Synonyms
- Sodium BldV-sCnc
- Category
- electrolyte
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 136
- Ref high
- 145
- Critical range
- 120 N/A – 160 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84295
- SNOMED
- 110741000
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test to diagnose or monitor conditions like dehydration, high blood pressure, kidney disease, or electrolyte imbalances. It can also help assess how well your body is retaining or losing fluids.
What to Expect Before the Test
No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re concerned about needles, let your provider know so they can offer alternatives.
What the Results Mean
Results are compared to a standard range, but exact numbers vary by lab. Low sodium (hyponatremia) may cause dizziness or confusion, while high sodium (hypernatremia) could lead to muscle spasms or rapid heartbeat. Always discuss results with your doctor.
Common Conditions This Test Helps Identify
This test is often used to spot signs of conditions like heart failure, kidney problems, or excessive sweating (e.g., from heat or illness). It can also help track how well medications are working to balance fluids in your body.
Reference range
Adult: 136-145 mmol/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Sodium is vital for nerve and muscle function, but imbalances can cause serious health issues. Low sodium can lead to swelling, seizures, or even coma in severe cases. High sodium may strain your heart or kidneys over time. Your doctor will use these results to guide treatment, such as adjusting medications or fluid intake.
Short name
Sodium Level
Frequently asked questions
What causes sodium levels to be too low?
What causes sodium levels to be too high?
How often should I get this test?
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