Thyroid health: interpreting symptoms, diagnosing & treating dysfunction, & navigating the gray zone

The gist

1. Attia says thyroid hormone is unlike testosterone in that too much causes real damage, including atrial fibrillation, bone loss, and cognitive dysfunction.
2. TSH, the standard test, does not show how much active T3 is reaching your liver, heart, or brain, where the conversion from T4 happens.
3. Fatigue and weight gain are non-specific symptoms that also appear in sleep deprivation and iron deficiency, so Attia recommends starting with labs rather than symptoms.
4. Attia warns that some practitioners treat borderline markers like elevated reverse T3 as disease even when TSH and free T4 are normal, using narratives that often resolve on their own.