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Nutrition Medium #iodine#thyroid#metabolism

Iodine and Thyroid

Iodine goes into T4. T4 converts to active T3 in tissues. Deficiency stalls the entire endocrine line.

A free, animated iodine and thyroid you can read here or embed on any website, from Scrollchart.

Iodine and Thyroid

Iodine to Thyroid Hormone CascadeDietary iodide becomes T4 in the gland, then active T3 in tissuesThyroid glandPeripheral tissues1Iodide trapping (NIS)dietary I- pulled into follicular cells2TPO organificationI- oxidised, attached to thyroglobulin tyrosines3MIT + DIT couplingDIT + DIT -> T4MIT + DIT -> T34Secretion ratioapprox 90% T4, 10% T3 released to bloodPituitary TSH feedbacklow iodine raises TSH, stimulates NIS and TPO, drives gland hypertrophysustained: goiter (visible enlargement)bloodstream5Deiodinase D1 + D2strip one iodine from T4 to yield active T3 in tissues6T3 binds TR-alpha, TR-betasets BMR, heart rate, body temperature, moodDeficiency cascadelow iodine, low T4/T3, high TSH, goiterfatigue, cold intolerance, weight gaincognitive slowing, dry skin, bradycardiaAdequate intake: 150 ug/day adult, 220 ug pregnantSources: iodised salt, seaweed, dairy, white fish. Selenium is required for deiodinase activity in step 5

Iodide trapping by the thyroid, organification, T4 and T3 synthesis, peripheral T4-to-T3 conversion. Deficiency causes goiter and hypothyroid symptoms.

Good for

  • Articles explaining why iodised salt matters and what happens without it
  • Prenatal-nutrition content on the 220 ug/day pregnancy requirement
  • Educational content connecting selenium status to T4-to-T3 conversion

Source & accuracy

This iodine and thyroid is an editorial illustration built to represent the concept accurately. Where it shows figures, they are typical or representative values chosen to make the relationship clear, not a single underlying dataset. The diagram and its explainer are reviewed and maintained centrally, and updated over time as understanding improves.

Iodine as the raw material for thyroid hormone

The thyroid gland traps dietary iodine and incorporates it into thyroid hormone. Each molecule of T4 (thyroxine) carries four iodine atoms; T3 carries three. T4 is the main hormone the gland releases, but it is comparatively inactive: peripheral tissues convert it to the more active T3 by removing one iodine, a step that depends on selenium-containing deiodinase enzymes.

Because iodine sits at the start of this line, a shortage limits how much hormone can be made regardless of how well the rest of the system works.

What deficiency does downstream

Persistent iodine shortfall can stall hormone production, prompting the gland to enlarge (goiter) as it tries to compensate. In pregnancy, adequate iodine is particularly important because thyroid hormone is critical for fetal brain development, and severe deficiency historically caused serious developmental harm. Salt iodization has greatly reduced this worldwide.

This is general educational information, not medical advice. Both too little and too much iodine can disturb thyroid function, so testing and any supplementation should be directed by a qualified clinician.

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Reference

What this is
A free, embeddable, animated iodine and thyroid for any website.
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Nutrition blogs, Health blogs, Medical educators.
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Frequently asked questions

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