Deiodinase

links: reference: 4-27-2021

Iodothyronine Deiodinase #

Peroxidase enzyme involved in activation/deactivation of thyroid hormones.

• Type I: Iodotyrosine deiodinase: found in liver and kidney
  • Scavenges iodide by removing it from iodinated Tyrosine residues in the thyroid gland.
• Type II: Iodothyronine 5’-deiodinase
  • T4->T3
• Type III: Thyroxine 5-deiodinase
  • T4->rT3
  • T3->T2
• Maternal High-Fat Diet Modulates the Fetal Thyroid Axis and Thyroid Gene Expression in a Nonhuman Primate Model
  • Maternal high fat diet crashes D_II in fetal macaque ilvers.

T4->T3 Conversion #

3 types of iodothyronine Deiodinase is responsible for the conversion. That which ‘inhibits’ this process probably increases either the affinity or quantity of type III (thyroxine 5-deiodinase) which converts T4->rT3 and T3-T2.

• • T3/T4 ratio decreases with aging and sickness Occurs especially in the Liver and Kidneys. Women may have a problem with this, considering estrogen may put a burden on the liver.
• https://www.youtube.com/watch?v=3fVx5yk73t4
• Cytokines inhibit it.
• Caloric deficit, hypogylcemia, and cortisol inhibits T4->T3 conversion
• Insulin, Growth Hormone, Zinc, and IGF-1 stimulates it.
• Selenium is required for the enzyme that deiodinizes T4 to convert into T3. Adequate levels of iodine and selenium are necessary for thyroid hormone metabolism. A high dose of iodine without selenium can cause inflammation, though.