Selenium Blood Test
This page explains the selenium blood test, what it measures, and how to arrange it. A selenium blood test measures the amount of selenium in your blood. Selenium is a mineral that supports thyroid function, immune health, and antioxidant defenses. The test is ordered when a deficiency or excess is suspected, or to monitor supplementation.
- Sample type
- blood
- Category
- General Wellness
- Turnaround
- 1-3 business days
- Price
- $179
- Referral
- Not required
A selenium blood test measures the amount of selenium in your blood. Selenium is a mineral that supports thyroid function, immune health, and antioxidant defenses. The test is ordered when a deficiency or excess is suspected, or to monitor supplementation.
What it measures
- Selenium (total) — The main mineral level in your blood, reported in micrograms per liter (mcg/L).
- Selenium (plasma or serum) — The liquid part of blood, often used for routine testing.
- Selenium (whole blood) — Measures selenium inside red blood cells, reflecting longer-term levels.
- Glutathione peroxidase (optional) — An enzyme that depends on selenium; sometimes checked with selenium.
Who it is for
A clinician may order this test if you have symptoms of deficiency (such as fatigue or muscle weakness) or excess (such as hair loss or nail changes), or if you are on long-term selenium supplements or intravenous nutrition.
Preparation
No fasting is usually required. Tell your clinician about all supplements, especially selenium, and any medications you take.
Results and what they mean
Results are reported as a number with a reference range, typically in mcg/L. Your clinician interprets the result along with your symptoms, diet, and other tests. This is general information, not medical advice; only a qualified professional can diagnose or treat a condition.
How to order this test
- Choose the test and place a confidential order online.
- Select a certified collection site and pick a time that suits you.
- Have your specimen collected — most draws take only a few minutes.
- Review results in a secure portal, typically within 1–3 days.
Preparation, hours, and pricing vary by site; confirm details directly with the lab before your visit.
Availability by state
Direct-access online ordering for the selenium blood test is available in most states. It is currently unavailable in 6 states:
Everywhere else you can order confidentially and collect your sample at a certified site. Browse by state →
Frequently asked questions
Do I need to fast for a selenium blood test?
No, fasting is not required. You can eat and drink normally before the test.
What can affect my selenium level?
Diet (especially Brazil nuts and seafood), supplements, and certain medical conditions can affect your level.
Is this test covered by insurance?
Coverage depends on your insurance plan and the reason for testing. Check with your insurer or the lab.
How soon will I get results?
Most results are ready within 1–3 business days. Your clinician will discuss what they mean for you.