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Iodothyronine Deiodinase

Three selenoenzymes (D1, D2, D3) that activate and inactivate thyroid hormones by removing iodine: D1 and D2 convert T4 to active T3, D3 inactivates T3 and T4 to reverse T3 and T2.

Also: DIO1, DIO2, DIO3

D1 (liver, kidney, thyroid) and D2 (brain, pituitary, brown fat) supply circulating and intracellular T3. D3 (placenta, fetal tissues, hypothalamus) terminates thyroid hormone signaling. Selenium deficiency disrupts thyroid hormone economy. The 12th edition uses deiodinases as the canonical case of nutrient-cofactor coupling between two micronutrients (selenium and iodine).

How one textbook covers it

  • Modern Nutrition in Health and Disease, 12th ed. — Ch 14: Iodine

    D1 (liver, kidney, thyroid) and D2 (brain, pituitary, brown fat) supply circulating and intracellular T3. D3 (placenta, fetal tissues, hypothalamus) terminates thyroid hormone signaling. Selenium deficiency disrupts thyroid hormone economy. The 12th edition uses deiodinases as the canonical case of nutrient-cofactor coupling between two micronutrients (selenium and iodine).

Related terms

Iodine, Selenium, Selenoprotein, Thyroid hormone