Selenium
Selenium is a trace mineral incorporated into selenoproteins including iodothyronine deiodinases that convert T4 to active T3, and glutathione peroxidases that protect the thyroid from oxidative stress. Deficiency impairs thyroid hormone conversion and may worsen autoimmune thyroid disease, while excessive supplementation is toxic. Brazil nuts, seafood, and organ meats are dietary sources.
Optimal range: who says what
Institutions, researchers and practitioners draw the line in different places. Each position is listed with who holds it and, where a document states it, a link. How we verify ranges.
- Institution or study90-130 ug/LMid-range; selenium shows a U-curve with both deficiency and excess harmful
- Lab reference interval70-150 μg/LWhat a lab report flags against. A lab interval is not an optimal target.
1 providers include this
Thyroid Function
Why Selenium matters
Essential for thyroid hormone conversion and antioxidant protection. Deficiency impairs thyroid function. Important for autoimmune thyroid disease.
Which Providers Test Selenium?
Of the panels we itemize, only Function Health ($365/year, 160+ biomarkers) includes Selenium.
1 panel that includes it, cheapest first
| Provider | Annual Cost | Total Biomarkers | $/Biomarker |
|---|---|---|---|
 Function Health | $365 | 160+ | $2.28 |
$/Biomarker is annual cost divided by the panel's advertised biomarker count, not the price of this one test. We track 23 blood test providers (32 plans); 21 of those plans are itemized marker by marker. Compare all of them.
20 itemized panels do not include Selenium
Superpower · WHOOP Advanced Labs · Labcorp OnDemand · Life Extension Elite · Everlywell · Mito Health · InsideTracker · Marek Health Base · Marek Health Comprehensive · Marek Health Complete · Marek Health Executive · Blueprint · Empirical Health · Oura Health Panels · SiPhox Health · Hims Labs · Healthspan · Vitality Blueprint Standard · Vitality Blueprint Elite · Ultrahuman Blood Vision Annual
11 providers not itemized in our matrix
We have not itemized these marker by marker (some sell tests one at a time), so this page cannot say whether they offer Selenium. Check with them directly.
Life Extension Standard · Quest Health · Ultrahuman Blood Vision · Lifeforce · Hundred Health · Personalabs · Walk-In Lab · HealthLabs · WHOOP Specialized Panels · Marek Health Essential · Vitality Blueprint Upload
Experts discussing Selenium
Podcast episodes where clinicians and researchers cover this marker in depth. Curated by hand; an episode is listed only when the marker is a substantial topic, not a passing mention.
- How to Control Your Metabolism by Thyroid & Growth HormoneDisclosure: Huberman Lab has been sponsored by Function Health, which appears in our blood-test comparisons.
Frequently Asked Questions
What is the optimal range for Selenium?
Published position: 90-130 ug/L (Mid-range; selenium shows a U-curve with both deficiency and excess harmful). Lab reference interval: 70-150 μg/L. That is what a lab report flags against, not an optimal target.
Which blood test providers include Selenium?
1 of the 21 blood testing panels we itemize marker by marker include Selenium in their panels. This biomarker has limited availability.
Related: YouBoost rates lifestyle and supplement interventions by evidence.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed Aug 26, 2026 · First published Sep 30, 2025