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Serum or plasma sodium concentration (qualitative screening)

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

This test measures the amount of sodium in your blood, which helps balance fluids and maintain proper cell function.

Quick summary

["Sodium levels are critical for heart health, muscle function, and preventing fluid imbalances."]

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

Key facts at a glance

LOINC
25821-0
Short code
S aureus Etx A IgE Qn
Synonyms
S aureus Etx A IgE Qn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 check for conditions like dehydration, kidney problems, or electrolyte imbalances. It can also help diagnose high blood pressure or heart issues.

What to Expect Before the Test

You’ll likely have a simple blood draw from a vein in your arm. No special preparation is needed unless your doctor instructs otherwise.

What the Results Mean

Results are qualitative (yes/no) rather than numeric, so your doctor will interpret them based on your overall health and symptoms.

Common Conditions Linked to Sodium Levels

High sodium (hypernatremia) may cause confusion, rapid heartbeat, or swelling, while low sodium (hyponatremia) can lead to headaches, fatigue, or seizures.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

What causes sodium levels to be checked?
Doctors may check sodium levels if you have symptoms like excessive thirst, confusion, muscle twitching, or signs of dehydration. It’s also used in monitoring patients with kidney disease, heart failure, or certain medications that affect sodium.
How long does it take to get results?
Results are typically available within a few hours to a day, depending on lab processing times. Your doctor will discuss findings during your follow-up visit.
Can diet affect sodium test results?
Yes, high-sodium foods or excessive water intake can temporarily alter sodium levels. Avoid extreme dietary changes before testing, but follow your doctor’s advice if needed.
  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