Selenium
What This Test Measures
Thyroid, antioxidant, immune function
Conventional vs. Functional Optimal Range
The gap between these ranges is why you feel terrible with "normal" labs. Conventional medicine waits for disease. Functional medicine optimizes for health.
Gabriel's Take
Selenium matters for T4→T3 conversion and thyroid health. Low selenium (<100) is linked to poor thyroid function and weaker immunity. Gabriel's optimal band is 110-130 μg/L. In Hashimoto's, selenium lowered TPO antibodies in trials (moderate certainty), but it hasn't been shown to keep the disease from progressing. The window is narrow: in one long trial, selenium supplements raised type 2 diabetes risk, most in people whose levels were already high (Annals of Internal Medicine, 2007). Brazil nuts vary widely in selenium.
When This Test Is High
Toxicity (rare, >200)
When This Test Is Low
Deficiency: poor thyroid conversion, immune dysfunction
Related Conditions
Hypothyroidism, immune dysfunction, increased cancer risk
Recommended Follow-Up
If low, ask a clinician about selenium from food or a supplement and recheck in 2-3 months; if your level is already in range, more is not better