Reference Ranges
Clinical Reference
0.4 – 4.0 mIU/L
Optimal Range
1.0 – 2.5 mIU/L
Critical Range
< 0.05
/
> 20.0
mIU/L
Varies by lab; functional medicine prefers <2.5
Related Conditions
Hypothyroidism
High
Hyperthyroidism
Low
Food & Lifestyle Recommendations
🍎 Food
Ensure adequate iodine intake (iodized salt, seaweed, fish); avoid excessive raw cruciferous vegetables
Iodine deficiency is the leading cause of hypothyroidism worldwide
🍎 Food
Ensure adequate selenium (Brazil nuts, fish, eggs) and zinc (pumpkin seeds, legumes)
Selenium and zinc are required for thyroid hormone synthesis and conversion
🧘 Stress
Chronic stress may worsen autoimmune thyroiditis; consider stress management practices
Stress can exacerbate autoimmune conditions including Hashimoto's
Evidence-Backed Supplements
When High
-
Meta-analyses show TSH reduction in autoimmune thyroiditis
Reduce selenium intake Consult physician N/A -
Essential for thyroid hormone synthesis; caution in autoimmune
-
Selenium is cofactor for deiodinase enzymes; supplementation may improve thyroid hormone conversion
Reduce selenium intake Consult physician N/A
Questions to Ask Your Doctor
- Should I be tested for thyroid antibodies to determine if this is autoimmune thyroiditis? TPO and Tg antibodies differentiate Hashimoto's
- Given my elevated TSH, should we also check Free T3 and Free T4? Full thyroid panel reveals conversion issues
- Should I be concerned about hyperthyroidism, and what symptoms should I watch for? Weight loss, rapid heartbeat, anxiety, heat intolerance
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