Selenium — What It Means in Your Blood Test
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Selenium protects your cells from damage, supports your thyroid, and helps your immune system.
A Selenium result reflects your supply of this trace mineral. Even in tiny amounts, it guards your cells against wear, lends a hand to your thyroid, and steadies your defences.
Also known as: serum selenium, Se, plasma selenium, selenium level, selenoprotein
This isn't a case where higher or lower is better. Your body keeps it in a narrow band, and both directions can matter.
Last reviewed: 2026-08-16
What does Selenium do in your body?
This trace mineral becomes built into proteins that mop up harmful, unstable molecules wearing on your cells [Institute of Medicine, 2000]. The same proteins help your thyroid gland make its hormone. A good supply steadies your defences. Doctors read it when a shortfall seems likely from diet, soil, or thyroid trouble.
What is Selenium?
Selenium is a mineral your body needs in small amounts. It is part of proteins that protect your cells, support your thyroid, and help your immune system. This test measures your level.
Why is Selenium tested?
Your doctor may order this test if a shortage is likely from your diet or local soil, or if your thyroid is not working well.
What is a normal Selenium range?
- India
- No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison.
- Global
- Normal: 7–25 µg/dL (70–250 µg/L) (NIH Office of Dietary Supplements 2021)
Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.
Source: [Institute of Medicine, 2000]
What does your Selenium value mean?
There is no widely-accepted set of value bands for this parameter. Compare your result with the reference range printed on your own report, and discuss it with your doctor.
What does a high Selenium result mean?
A high level, from supplements or selenium-rich soil, can cause brittle hair and nails, a garlic-like breath, and nerve effects worth discussing with your doctor.
What does a low Selenium result mean?
A low level can cause muscle pain, changes in how your thyroid works, and weaker protection for your cells.
What happens when your Selenium is low?
Selenium is built into proteins that mop up harmful molecules and help the thyroid make its hormone. A shortfall weakens both jobs [Institute of Medicine, 2000].
Which foods are rich in Selenium?
- In India
- whole grains, eggs, and nutsICMR-NIN (2017)
- Internationally
- Brazil nuts, seafood, eggs, and whole grainsUSDA FoodData Central (2024)
What can affect your Selenium result?
- Selenium in local soil
- Seafood and Brazil nuts
- Kidney function
- Gut absorption problems
- Where your food is grown
Questions to ask your doctor
About this result
- What does my Selenium result mean for me specifically, given my age and health?
- Is my Selenium in the range that is right for me, not just the lab's general range?
What to do next
- Could anything I eat, do, or take have affected my antioxidant trace mineral result?
- Is there anything I should do about my Selenium, or is it fine to leave as it is?
About retesting
- Does my Selenium need to be repeated, and if so, when?
- The typical range for Selenium can vary between labs — should I compare my result against my own lab's printed range?
The bigger picture
- Should my Selenium be looked at together with my Calcium and Ionised Calcium result?
- Does my Selenium connect to any condition I already have, or to anything I have noticed in how I feel?
Frequently asked questions
- What is Selenium?
- Selenium is a mineral your body needs in small amounts. It is part of proteins that protect your cells, support your thyroid, and help your immune system. This test measures your level. Your doctor may order this test if a shortage is likely from your diet or local soil, or if your thyroid is not working well.
- What is a normal antioxidant trace mineral range?
- A typical adult range is around Normal: 7–25 µg/dL (70–250 µg/L) (NIH Office of Dietary Supplements 2021). No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison. Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.
- What does a high Selenium result mean?
- A high level, from supplements or selenium-rich soil, can cause brittle hair and nails, a garlic-like breath, and nerve effects worth discussing with your doctor.
- What does a low Selenium result mean?
- A low level can cause muscle pain, changes in how your thyroid works, and weaker protection for your cells.
- What can affect your Selenium result?
- Several everyday factors can influence it, including Selenium in local soil, Seafood and Brazil nuts, Kidney function, Gut absorption problems, Where your food is grown.
Sources
Part of the Minerals
Related tests in this panel
Related reading
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