Serum or Plasma Sodium (Substance Concentration)
This test measures the amount of sodium, a key electrolyte, in your blood or plasma. Sodium helps regulate fluid balance and nerve/muscle function.
Sodium levels help doctors check if you’re retaining or losing too much fluid or have conditions like high blood pressure or kidney issues.
Key facts at a glance
- LOINC
- 94416-5
- Short code
- SCN1A c.603-91G>A Geno Bld/T
- Synonyms
- SCN1A c.603-91G>A Geno Bld/T
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- molgen
- 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 Sodium Levels Matter
Sodium is essential for maintaining proper fluid balance in your body. Too much sodium can lead to dehydration, high blood pressure, or swelling, while too little can cause confusion, muscle cramps, or irregular heartbeat. Your doctor may order this test if you have symptoms like excessive thirst, swelling, or unexplained weight changes.
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 finger to draw blood, or your doctor may collect plasma from a blood draw. If you’re tested for urine sodium, you may need to collect a sample at home or in a lab.
What the Results Mean
Results are compared to a standard range for healthy adults, though your doctor will interpret them based on your overall health and symptoms. Very high or very low sodium levels can signal underlying health issues that need medical attention.
Common Causes of Abnormal Results
High sodium levels (hypernatremia) can occur from dehydration, excessive salt intake, or conditions like diabetes insipidus. Low sodium levels (hyponatremia) may result from kidney problems, excessive sweating, or overuse of diuretics.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal sodium levels are often a red flag for conditions like heart disease, kidney dysfunction, or hormonal imbalances. Your doctor may monitor sodium levels regularly if you have chronic conditions like heart failure, liver disease, or certain medications that affect fluid balance.
Short name
Sodium Level
Frequently asked questions
What triggers a sodium test?
How long does it take to get results?
Can I eat or drink before the 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