Endocrine & metabolic · UKMLA & AKT
Drug-induced and factitious thyrotoxicosis
A free high-yield preview for the UKMLA Applied Knowledge Test. Below are the key points to recognise drug-induced and factitious thyrotoxicosis — the full SA Note notes add investigations, management, complications and 10 practice questions.
Key high-yield points
- Beta-hCG and TSH share identical alpha subunits - at very high concentrations (e.g. molar pregnancy), beta-hCG cross-reacts with TSH receptors on thyroid follicular cells, stimulating T4/T3 production
- Elevated T4/T3 exerts negative feedback on the pituitary → suppressed TSH
- Result: high beta-hCG + low TSH + high thyroxine - the expected pattern in gestational trophoblastic disease (hydatidiform mole)
Molar pregnancy = very high beta-hCG → TSH receptor stimulation → thyrotoxicosis. TFTs show suppressed TSH + elevated FT4/FT3. Definitive treatment is uterine evacuation.
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