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Levothyroxine absorption interaction — GPhC CRA MCQ

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HardEndocrine TherapeuticsLevothyroxine absorption interactionGPhC CRA

A 43-year-old woman taking levothyroxine 100 micrograms daily says her TSH remains high. She takes levothyroxine with breakfast, ferrous sulfate, and a calcium supplement. What would you advise the patient?

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

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Correct answer: B — Take levothyroxine on an empty stomach and separate it from iron and calcium

Iron and calcium can reduce levothyroxine absorption, and food can also affect consistency of absorption. Levothyroxine is usually taken on an empty stomach with separation from interacting supplements. Persistent abnormal TSH should also prompt adherence review and prescriber follow-up.

Reference: BNF; NICE CKS