Primary hypothyroidism — RACGP Fellowship MCQ

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ModerateChronic disease managementPrimary hypothyroidismRACGP Fellowship

A 42‑year‑old woman presents with fatigue, weight gain, constipation and dry skin. Her thyroid function tests reveal TSH 18 mIU/L and low free T4. She is not pregnant and has no cardiac disease. What is the most appropriate initial management?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: B — Start levothyroxine and monitor TSH after dose adjustment

Explanation lettering: D = shown as C · C = shown as D

The stem indicates overt primary hypothyroidism: elevated TSH (18 mIU/L), low free T4, and symptomatic presentation in a patient without pregnancy or cardiac comorbidity. Therapeutic Guidelines (via Australian Prescriber) state that primary hypothyroidism is treated with lifelong levothyroxine replacement ([australianprescriber.tg.org.au](https://australianprescriber.tg.org.au/articles/modern-management-of-thyroid-replacement-therapy.html?utm_source=openai)). RACGP guidance recommends levothyroxine where TSH >10 mIU/L, with monitoring every 6–8 weeks until stable ([racgp.org.au](https://www.racgp.org.au/afp/2012/august/hypothyroidism/?utm_source=openai)). Options are plausible distractors: (A) Carbimazole is for hyperthyroidism; (C) pituitary MRI is for secondary (low TSH) hypothyroidism; (D) observation is for subclinical cases (TSH mildly elevated); (E) liothyronine monotherapy is unnecessary and not first-line.

Reference: Australian Prescriber: Modern management of thyroid replacement therapy (2008); RACGP: Hypothyroidism: Investigation and management (2012), https://australianprescriber.tg.org.au/articles/modern-management-of-thyroid-replacement-therapy.html