Sodium concentration in serum/plasma
This test measures the amount of sodium, a key mineral, in your blood. Sodium helps balance fluids and maintain normal blood pressure.
["Sodium levels help doctors check if you have too much or too little sodium in your blood."]
Key facts at a glance
- LOINC
- 49790-9
- Short code
- Sodium Prt-sCnc
- Synonyms
- Sodium Prt-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 This Test Matters
Sodium is vital for many bodily functions, including nerve and muscle activity, fluid balance, and blood pressure regulation. Abnormal levels can cause serious health issues, such as dehydration, swelling, or heart problems. Your doctor may order this test to diagnose or monitor conditions like kidney disease, heart failure, or excessive sweating.
What to Expect Before the Test
No special preparation is needed for this test. You may have a small needle inserted into your arm or vein to draw blood. If you’re on a sodium-restricted diet, let your doctor know before the test.
Possible Causes of Abnormal Results
High sodium levels (hypernatremia) may occur from dehydration, excessive salt intake, or kidney problems. Low sodium levels (hyponatremia) can result from excessive sweating, vomiting, diarrhea, or certain medications. Your doctor will discuss symptoms and other test results to determine the cause.
Common Conditions Monitored
Doctors often check sodium levels in patients with symptoms like confusion, swelling, rapid heartbeat, or unexplained weight gain. It’s also used to monitor people with chronic conditions like heart failure, liver disease, or kidney problems.
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.
Clinical Significance
Short name
Sodium Level
Frequently asked questions
What does a low sodium level mean?
What does a high sodium level mean?
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