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Levothyroxine absorption — GPhC CRA MCQ

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ModerateEndocrine TherapeuticsLevothyroxine absorptionGPhC CRA

A patient taking levothyroxine 100 micrograms each morning has started ferrous sulfate for iron deficiency. Their TSH has risen after previously being stable. They take both tablets together with breakfast. What is the most important interaction to flag?

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

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Correct answer: E — Separate levothyroxine from iron and take levothyroxine consistently on an empty stomach

Iron salts reduce levothyroxine absorption and can lead to loss of thyroid control. Levothyroxine should be taken consistently, usually before breakfast, separated from iron, calcium and some other interacting medicines. The dose should not be doubled without prescriber direction. Stopping levothyroxine risks hypothyroid symptoms.

Reference: BNF