Sodium concentration in serum
This test measures the amount of sodium, a key mineral, in your blood serum. Sodium helps balance fluids and maintain normal blood pressure and nerve/muscle function.
["Sodium levels help doctors check if you have fluid imbalances or conditions like high blood pressure or kidney problems."]
Key facts at a glance
- LOINC
- 32340-2
- Short code
- Sodium Spec-sCnc
- Synonyms
- Sodium Spec-sCnc
- Category
- electrolyte
- Sample
- serum
- Container
- Red-top tube (SST)
- 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
- 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 healthcare provider may order this test to diagnose or monitor conditions such as dehydration, kidney disease, heart failure, or excessive sweating. It can also help assess electrolyte imbalances or determine if you need fluid adjustments, such as in IV therapy.
What to Expect Before the Test
You typically won’t need special preparation. If you’re on a low-sodium diet, check with your doctor first. Avoid drinking extra water or eating high-sodium foods 24 hours before the test if instructed.
During the Test
A healthcare professional 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 the Results Mean
Results are compared to a standard range for healthy adults. Low sodium levels (hyponatremia) may cause headaches, confusion, or muscle cramps, while high levels (hypernatremia) can lead to thirst, fatigue, or irregular heartbeat. Your doctor will discuss your specific results in the context of your health.
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.
Abnormal sodium levels can signal serious underlying issues. Low sodium can result from excessive sweating, kidney problems, or certain medications, while high sodium may indicate dehydration, kidney failure, or overuse of salt. Regular monitoring helps manage conditions like heart disease, liver disease, or hormonal imbalances.
Short name
Serum Sodium Level
Frequently asked questions
How Long Does It Take to Get Results?
Can I Eat or Drink Normally Before the Test?
What If My Sodium 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