Serum or Plasma Sodium (Electrolyte Measurement)
This test measures the amount of sodium in your blood. Sodium helps balance fluids and maintain proper heart and nerve function.
["Sodium levels help doctors check if you’re retaining or losing too much fluid or salt."]
Key facts at a glance
- LOINC
- 10104-8
- Short code
- ST Slope L-V5
- Synonyms
- ST Slope L-V5
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ekg
- 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 doctor may order this test to diagnose or monitor conditions like dehydration, kidney problems, heart disease, or high blood pressure. It can also help assess whether you’re taking in too much or too little sodium through diet or medications.
What to Expect Before the Test
No special preparation is needed. You may be asked to fast for 8–12 hours before the test if it’s part of a broader blood panel, but this isn’t always required for a standalone sodium test. Bring any medications or supplements you’re taking to your appointment.
What Happens During the Test?
A healthcare provider will draw blood from a vein in your arm using a small needle. 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 Are the Results?
Results are typically reported in milliequivalents per liter (mEq/L). A low sodium level (hyponatremia) or high sodium level (hypernatremia) may signal underlying health issues that need further evaluation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormally low sodium can cause headaches, confusion, nausea, or even seizures in severe cases. High sodium levels may lead to dehydration symptoms like thirst, dry mouth, or irregular heartbeat. Both extremes can affect organ function and require medical attention to address the underlying cause, such as fluid imbalance or kidney dysfunction.
Short name
Sodium Level
Frequently asked questions
How long does it take to get my sodium test results?
What does a low sodium level mean?
Can I eat or drink before a sodium 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