Common thyroid myths and what the evidence shows

Myth Not supported

“My TSH is 'normal' but not 'optimal' - that's why I feel bad”

EvidenceBlinded randomized trials found no difference in symptoms or quality of life when the dose was adjusted to different TSH levels within the normal range. The concept of 'optimal' TSH lacks scientific support. ↗︎ ↗︎

Myth Not supported

“I can't convert T4 to T3 properly”

EvidenceMultiple randomized trials show no benefit of adding T3 over T4-alone therapy for most patients. ↗︎ ↗︎

Myth Not supported

“Reverse T3 is blocking my thyroid function”

EvidenceReverse T3 testing has no validated clinical utility. It's a normal metabolic byproduct. ↗︎

Myth Not supported

“I need my TSH under 1.0 to feel good”

EvidenceNo evidence supports this common online claim. Wellbeing scores are similar across the normal range. ↗︎ ↗︎

Myth Not supported

“Natural desiccated thyroid is better than synthetic”

EvidenceRandomized trials found no difference in symptoms or quality of life, although about half of participants in one trial preferred it and lost a little weight. Guidelines keep levothyroxine as standard care. ↗︎ ↗︎