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Serum Sodium (Electrolyte)

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

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

Quick summary

["Sodium levels help doctors check for dehydration, kidney issues, or other health concerns."]

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

Key facts at a glance

LOINC
63340-4
Short code
ENA SS-A 52kD Ab Titr Fld IA
Synonyms
ENA SS-A 52kD Ab Titr Fld IA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
86430
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, high blood pressure, kidney disease, or electrolyte imbalances. It’s also used to assess how well your body is retaining or losing sodium, especially after treatments like diuretics or IV fluids.

What to Expect Before the Test

No special preparation is needed. You may drink water as usual, but avoid excessive salt intake 24 hours before testing. If you’re on medications that affect sodium levels, let your doctor know.

What Happens During the Test?

A small blood sample is drawn from a vein in your arm. It usually takes a few minutes, and you may feel a slight pinch. The sample is sent to a lab for analysis.

What the Results Mean

Results are compared to standard ranges for your age and health. Low sodium (hyponatremia) can cause headaches or confusion, while high sodium (hypernatremia) may lead to fatigue or irregular heartbeat. Your doctor will discuss your specific results with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal sodium levels can indicate serious conditions, such as kidney problems, heart disease, or hormonal imbalances. Sodium is critical for maintaining fluid balance, nerve function, and muscle contractions. Regular monitoring helps prevent complications like seizures or heart strain.

Short name

Sodium

Frequently asked questions

How long does it take to get my sodium test results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your doctor will contact you once they’re ready for review.
Can I eat or drink anything before this test?
You can drink water as usual, but avoid excessive salt intake 24 hours before testing. If you’re unsure, ask your doctor for specific instructions.
What should I do if I feel dizzy or lightheaded after the blood draw?
Rest for a few minutes in a quiet, comfortable space. Apply gentle pressure to the draw site, and apply ice if needed to reduce swelling. If symptoms persist, contact your doctor immediately.
  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