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Selenium Phenotype or Selenium Metabolism Screening (Serum/Plasma Concentration)

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

This test measures the amount of selenium in your blood, an essential mineral that supports immune function, thyroid health, and antioxidant protection.

Quick summary

["Selenium helps protect cells from oxidative damage and supports immune and thyroid function—check your levels if you have symptoms of deficiency or excess."]

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

Key facts at a glance

LOINC
61532-8
Short code
Selenium PhenX
Synonyms
Selenium PhenX
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
phenx
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 This Test Matters

Selenium is a vital micronutrient found in foods like nuts, seeds, and seafood. Low levels may contribute to fatigue, weakened immunity, or thyroid issues, while very high levels can cause toxicity symptoms like nausea or nerve damage. This test helps assess whether your levels are within the healthy range.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample (either serum or plasma) during a routine clinic visit. The test is quick and typically done while you’re seated.

What the Results Mean

Results show your selenium concentration in micrograms per deciliter (µg/dL). While reference ranges vary by lab, they generally fall between 0.70 and 2.0 µg/dL for adults. Your doctor will interpret results in the context of your overall health.

Common Reasons for Testing

Your doctor may order this test if you have symptoms like hair loss, frequent infections, muscle pain, or thyroid disorders. It’s also used in research or monitoring for selenium deficiency or toxicity.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Selenium Level

Frequently asked questions

How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your healthcare provider will contact you once they’re ready.
What foods are best for selenium?
Eat a varied diet rich in selenium, including Brazil nuts (just 1–2 nuts daily provide most of your needs), fish (salmon, sardines), eggs, and whole grains. If you have dietary restrictions, discuss supplementation with your doctor.
Can I take selenium supplements without checking my levels first?
No. High doses of selenium supplements can be harmful. Always consult your doctor before starting supplements, especially if you’re taking medications or have kidney issues.
  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