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Serum Sodium Concentration (Electrolyte Panel)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of sodium in your blood serum. Sodium is an important electrolyte that helps balance fluids and maintain nerve and muscle function.

Quick summary

["Sodium levels help doctors check if you have fluid imbalances or conditions like high blood pressure or kidney problems."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
60674-9
Short code
Na-A Skull XR
Synonyms
Na-A Skull XR
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-measured
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 such as dehydration, heart disease, kidney issues, or hormonal imbalances. It’s often part of a broader electrolyte check or routine blood work.

What to Expect Before the Test

You’ll typically have a small needle inserted into your arm to draw blood. No special preparation is needed, but avoid eating or drinking for a short time before if instructed by your provider.

What the Results Mean

Results are usually reported in milliequivalents per liter (mEq/L). Low sodium levels (hyponatremia) may cause headaches or confusion, while very high levels (hypernatremia) can lead to muscle spasms or irregular heartbeat.

Common Conditions Affecting Sodium Levels

Conditions like excessive sweating, vomiting, or diarrhea can lower sodium. Conversely, conditions like kidney problems, heart failure, or excessive salt intake may raise it. Your doctor will interpret results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Sodium Level

Frequently asked questions

What questions do patients often ask about sodium tests?
Is fasting required for this test? No fasting is usually required unless your doctor specifies otherwise. The test measures sodium in serum, which can be drawn at any time.
How long does it take to get results?
Results are typically available within 1–2 business days, depending on your lab’s processing time. Your doctor will discuss them with you during your follow-up visit.
Can I take electrolytes or salt supplements before the test?
Avoid excessive salt or electrolyte supplements for 24 hours before testing unless directed by your doctor, as they may affect sodium levels.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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