The Claim
In a 40-year-old woman with clinical euthyroidism, persistently elevated serum TSH levels (8.2–29 μU/mL) occur despite markedly elevated serum total T4 (mean 13.4 μg/dL) and T3 (mean 255 ng/dL), and T3 administration suppresses TSH secretion, indicating selective pituitary resistance to T4 that does not affect T3.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
A 40-year-old woman with normal thyroid function had high thyroid-stimulating hormone (TSH) levels despite high levels of both thyroxine (T4) and triiodothyronine (T3). When T3 was given, TSH dropped, but T4 did not suppress TSH, showing that the pituitary gland responds to T3 but not to T4.
See the scientific wording
A 40-year-old woman with clinical euthyroidism exhibited persistently elevated serum TSH levels (8.2–29 μU/mL) despite markedly elevated serum total T4 (mean 13.4 μg/dL) and T3 (mean 255 ng/dL), suggesting a selective pituitary resistance to T4 that does not extend to T3, as T3 administration effectively suppressed TSH secretion.
The pituitary gland does not respond to the main thyroid hormone T4, so it keeps making TSH even when T4 levels are high. But it does respond to T3, which shuts down TSH production. This happens because T4 cannot be properly used inside the pituitary cells, while T3 can bind directly and stop TSH production.
What the research says
1 studyThis woman’s brain kept making too much TSH even though her thyroid was making lots of hormones, but when doctors gave her T3, her brain finally stopped making extra TSH — meaning her brain can ‘hear’ T3 but not T4.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.