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Serum or plasma concentration of sodium (substance concentration)

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

This test measures the amount of sodium, a key mineral, in your blood. Sodium helps balance fluids and maintain normal blood pressure.

Quick summary

["Sodium levels help doctors check for fluid balance and kidney function."]

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

Key facts at a glance

LOINC
79578-1
Short code
N6-Ac-L-lys SerPl-sCnc
Synonyms
N6-Ac-L-lys SerPl-sCnc
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 healthcare provider may order this test to evaluate conditions like dehydration, kidney disease, heart problems, or high blood pressure. It can also help monitor fluid shifts or electrolyte imbalances.

What to Expect Before the Test

No special preparation is needed. You may be asked to fast before the test, but this depends on your doctor’s instructions. A small needle will be used to draw blood from a vein, usually in your arm.

What the Results Mean

Results are compared to a general reference range, but exact values can vary by lab. Low sodium (hyponatremia) may cause headaches or confusion, while high sodium (hypernatremia) could lead to muscle twitches or nausea.

Common Conditions Linked to Sodium Levels

Abnormal sodium levels can signal conditions like severe dehydration, kidney failure, or excessive sweating. Chronic conditions like heart disease or diabetes may also affect sodium balance.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Sodium Level

Frequently asked questions

How often should I get this test?
Your doctor will determine how often you need this test based on your health status, symptoms, or treatment plan. Regular checks may be needed if you have chronic conditions like kidney disease or heart failure.
Can diet affect sodium test results?
Yes, your diet can influence sodium levels. High-sodium foods or excessive salt intake may raise sodium, while low-sodium diets may lower it. Avoid salty foods for a few days before testing if instructed.
What if my sodium level is out of range?
If your sodium level is too high or too low, your doctor may recommend changes in diet, medications, or further tests. Immediate medical attention may be needed for severe imbalances.
  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