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Serum Selenium Concentration

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

This test measures the amount of selenium, a trace mineral essential for health, in your blood serum. Selenium helps protect cells from damage and supports immune function.

Quick summary

["Selenium is vital for immune support and cellular protection."]

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

Key facts at a glance

LOINC
25521-6
Short code
Selenium SerPl-sCnc
Synonyms
Selenium 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 check for selenium deficiency, which can occur due to poor diet, certain medical conditions, or malabsorption issues. It may also be used to monitor selenium levels in patients receiving selenium supplements or those with selenium-related disorders.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, similar to other routine blood tests. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Results are typically reported as a concentration value (in micrograms per deciliter or mcg/dL). While reference ranges vary by lab, low levels may indicate deficiency, while very high levels could signal conditions like selenium poisoning or certain metabolic disorders.

Common Reasons for Testing

This test is often performed in patients with symptoms like fatigue, muscle weakness, hair loss, or immune dysfunction. It may also be part of a broader evaluation for autoimmune diseases, thyroid disorders, or nutritional deficiencies.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Selenium is a critical antioxidant that supports immune function, thyroid hormone production, and DNA synthesis. Deficiencies can lead to weakened immunity, muscle pain, or neurological issues, while excess may cause toxicity symptoms like nausea or hair loss. Monitoring levels helps guide treatment for deficiencies or adjust supplement use.

Short name

Selenium Level

Frequently asked questions

What causes selenium levels to be low?
Low selenium levels can result from poor diet (low intake of selenium-rich foods like nuts, fish, or whole grains), certain medical conditions affecting absorption (e.g., Crohn’s disease), or long-term use of certain medications. Lifestyle factors, such as smoking or alcohol consumption, may also contribute.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab and healthcare provider. Follow-up may be needed if results are outside expected ranges.
Can I eat or drink anything before this test?
You can eat and drink normally before this test unless instructed otherwise. Avoid alcohol for 24 hours before testing, as it may affect blood composition.
  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