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Serum Sodium (Electrolyte Measurement)

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

This test measures the amount of sodium, a key electrolyte, in your blood serum. Sodium helps maintain fluid balance, nerve and muscle function, and blood pressure.

Quick summary

["Sodium levels help doctors check if you're retaining or losing too much fluid or electrolytes."]

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

Key facts at a glance

LOINC
60630-1
Short code
SeNa-SeGn Skull XR
Synonyms
SeNa-SeGn 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 This Test Matters

Sodium is vital for many bodily functions, including regulating blood volume, supporting nerve impulses, and maintaining muscle contractions. Abnormal levels can indicate conditions like dehydration, kidney problems, or heart issues.

What to Expect During the Test

A small blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab for analysis. Results are typically ready within a few hours to a day.

Common Causes of Abnormal Results

High sodium levels (hypernatremia) may occur due to dehydration, excessive salt intake, or kidney disorders. Low sodium levels (hyponatremia) can result from excessive fluid retention, vomiting, diarrhea, or certain medications.

How Your Results Are Used

Doctors use sodium test results to diagnose and manage conditions like heart failure, kidney disease, liver disease, or electrolyte imbalances. They may also guide treatment for conditions like hyponatremia or hypernatremia.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Sodium Level

Frequently asked questions

What does a sodium test measure?
A sodium test measures the concentration of sodium ions in your blood serum, which is essential for maintaining fluid balance and nerve function.
How long does it take to get sodium test results?
Results are usually available within a few hours to a day, depending on your lab’s processing time.
Can sodium levels change quickly?
Yes, sodium levels can fluctuate rapidly due to factors like dehydration, diet, or certain medications, so it’s important to follow up with your healthcare provider if you notice symptoms like confusion, nausea, or excessive thirst.
  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