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Levothyroxine and iron — GPhC CRA MCQ

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ModerateEndocrine TherapeuticsLevothyroxine and ironGPhC CRA

A patient taking levothyroxine 100 micrograms daily buys ferrous sulfate for iron deficiency. They plan to take both tablets together before breakfast. What is the most important interaction to flag?

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Correct answer: D — Reduced levothyroxine absorption and poorer thyroid control

Iron salts can bind levothyroxine and reduce absorption. The best answer addresses the key safety, legal or pharmaceutical care issue in the vignette. The other options would either delay appropriate care, create a new risk, or fail to resolve the issue. This is consistent with the cited UK reference for safe pharmacy practice.

Reference: BNF; NICE CKS