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Endocrinology — UKMLA MCQ

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A 42-year-old woman had longstanding untreated primary hypothyroidism with an initial TSH of 96 mU/L. Six weeks after starting an appropriate weight-based levothyroxine dose, symptoms are improving, FT4 is normal and TSH has fallen to 12 mU/L. Adherence and administration are correct. What is the best next step?

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Correct answer: AContinue the dose and repeat TSH at about 3 months

NICE advises measuring TSH every 3 months until it stabilises, defined as 2 similar in-range measurements 3 months apart. It also warns that TSH can take up to 6 months to return to range when the pretreatment TSH was very high or hypothyroidism was prolonged. Her improving symptoms, normal FT4 and substantial TSH fall therefore support continuing the current dose and reassessing at the recommended interval rather than reacting prematurely. Liothyronine is not routine treatment, and normalisation of FT4 does not justify stopping replacement.

Reference: NICE NG145, recommendations 1.4.1 to 1.4.4: https://www.nice.org.uk/guidance/ng145/chapter/recommendations