Removal of the entire thyroid gland eliminates all thyroid tissue and stops the body from producing thyroid hormones.

We analyzed one assertion about whether total thyroidectomy stops thyroid hormone production, and the evidence we’ve reviewed so far leans strongly against it. The assertion claims that removing the entire thyroid gland eliminates all thyroid tissue and stops hormone production, but this claim is contradicted by 29 studies or observations that show otherwise [1]. Thyroid hormone production doesn’t rely solely on the thyroid gland. Even after the gland is fully removed, the body can still produce small amounts of thyroid hormones through other pathways, such as the conversion of T4 to T3 in tissues like the liver, kidneys, and muscles. Additionally, patients who undergo total thyroidectomy are routinely prescribed synthetic thyroid hormone replacement, which confirms that the body no longer makes enough on its own — but also implies that hormone production doesn’t simply vanish the moment the gland is gone. The 29 refuting pieces of evidence suggest that hormone levels are managed externally because the body’s ability to regulate them is disrupted, not because production stops entirely in all forms. What we’ve found so far indicates that while the thyroid gland is the main source of thyroid hormones, its removal doesn’t mean all hormone production ceases — the body continues to process and convert existing hormone precursors. This doesn’t mean the person doesn’t need medication — they almost always do — but it does mean the mechanism is more complex than simply “no gland, no hormones.” In everyday terms: Taking out your thyroid doesn’t turn off your body’s ability to use thyroid hormones — it just stops the main supply, so you need to replace it with medicine.