Where does this come from, and can I check it?

T4 carries four iodine atoms and T3 carries three, which is why iodine is essential. The figure is taken from American Thyroid Association, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a human body fact?

Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

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The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Thyroid hormones are built around iodine atoms

T4 carries four iodine atoms and T3 carries three, which is why iodine is essential The thyroid traps iodide from the blood and attaches it to the amino acid tyrosine. Coupling these modified tyrosines produces T4 and small amounts of T3. T4 is the main output but T3 is the more active form, and other tissues convert one to the other as needed. It sits in Mondo's human body collection, one of 200 facts that each trace back to the reference below.

Where this comes from

American Thyroid Association

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Tags: thyroid, iodine, hormones

Thyroid hormones are built around iodine atoms: the short answers

Where does this come from, and can I check it?: T4 carries four iodine atoms and T3 carries three, which is why iodine is essential. The figure is taken from American Thyroid Association, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a human body fact?: Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.