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Selenium in Serum (Mass Concentration)

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

This test measures the amount of selenium, a trace mineral important for overall health, in your blood serum.

Quick summary

["Selenium helps support immune function, thyroid health, and antioxidant protection."]

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

Key facts at a glance

LOINC
23779-2
Short code
Selenium Spec-mCnc
Synonyms
Selenium Spec-mCnc
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, monitor selenium levels in certain conditions (like autoimmune diseases or malabsorption), or evaluate selenium toxicity. It can also be part of a broader nutritional assessment or screening for conditions affecting mineral balance.

What to Expect Before the Test

No special preparation is typically needed. You may be asked to fast for 8–12 hours before the draw if your lab requires it, but always follow your provider’s instructions. Bring any medications or supplements you take regularly to discuss with your healthcare team.

What Happens During the Test?

A healthcare professional will collect a blood sample from a vein in your arm. You may feel a slight pinch, but it usually takes only a few minutes. The sample is then sent to a lab for analysis.

What Are the Results Measured Against?

Results are compared to standard reference ranges for selenium in serum, which can vary slightly by lab. Your provider will interpret the results in the context of your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Selenium Level

Frequently asked questions

What causes selenium levels to change?
Selenium levels can be affected by diet (e.g., low intake of selenium-rich foods like nuts, fish, or whole grains), certain medications, chronic illnesses, or malabsorption disorders. Lifestyle factors, such as smoking or alcohol use, may also influence results.
How long does it take to get results?
Test results are typically available within 1–3 business days, depending on your lab’s processing time. Your provider will contact you once the results are ready, usually within a few days of receiving them.
Can I adjust my diet or supplements before this test?
If your provider hasn’t instructed otherwise, avoid making drastic dietary changes or stopping selenium supplements without consulting them first. Some supplements (like selenium) can affect test accuracy, so always follow their guidance.
  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