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Levothyroxine and iron — GPhC CRA MCQ

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EasyDrug InteractionsLevothyroxine and ironGPhC CRA

A patient taking levothyroxine starts ferrous sulfate for anaemia. They take both medicines together before breakfast. What is the most important interaction to flag?

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Correct answer: E — Reduced levothyroxine absorption from iron salts

Iron salts can bind levothyroxine and reduce absorption. Doses should be separated and thyroid control reviewed. In this scenario, the correct option is reduced levothyroxine absorption from iron salts. The other options are plausible but do not address the key clinical, legal or safety issue as directly. This aligns with UK pharmacy practice guidance cited in the reference field.

Reference: BNF; Stockley's Drug Interactions