Thyroid UK
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Treatment for iron-deficiency anaemia: would it affect the dose of thyroxine?

I've just started on ferrous fumarate for iron-deficiency anaemia (IDA). I feel more tired now than I did before, and this has got me thinking: does treatment of IDA have any effect on free T4 levels? Is it possible that by treating the IDA one needs to dial up or down the current dose of thyroxine?

Does anyone have any experience of this?

4 Replies

Hose, you need to take the iron very far apart from the thyroxine. So if you take the thyroxine first thing in the morning, take the iron in the afternoon and in the evening. Iron interferes with thryoxine absorption. Or if you take the thyroxine at bedtime, then you take the iron in the morning and in the early afternoon.

I posted a study yesterday indicating that taking 500 mg of Vitamin C with thyroxine improves absorption.

Taking vitamin C with iron also improves iron absorption.


I take my thyroxine in the morning and my iron, with 1000 mg vitamin c, at bedtime. So about 9 hours apart.

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In about 4 weeks time and your still feeling bad, ask for another blood test for your thyroid hormones. You may need an increase.


Perhaps it is worthy trying a different form of iron i.e. iron bisglycinate which is far easily absorbed. Noting that you won't need as many mg as the fumarate or other iron salts.


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