A combination of T3 and T4 thyroxine is usually preferred, as deiodinase
conversion of T4 to T3 is thought to be compromised in these settings (2).
An emerging concept in this field is that TH s pleiotropic actions can be amplified or attenuated at cell level by the deiodinase
enzymes that can increase (D2) or decrease (D3) the active TH concentration regardless of hormone plasma levels.
The peripheral metabolism of thyroid hormones is catalyzed by deiodinase
Selenium is implicated in antioxidant functions, and selenocysteine complex is essential in the active centres of Se-enzymes that carry out redox reactions, glutathione peroxidase (GPx), thyroid hormone deiodinase
families and thioredoxinreductase (Tapiero et al.
Once T4 reaches the peripheral tissues, it is converted into its biologically active form, triiodothyronine (T3), by the deiodinase
However, more recent work has shown that a relatively common polymorphism of the deiodinase
2 gene known as Thr92Ala may predict less responsiveness of psychological symptoms of hypothyroidism to optimal LT4 monotherapy.
Type 1 deiodinase
(D1) enzyme is not expressed in bone.
Huang SA, Tu HM, Harney JW, et al: Severe hypothyroidism caused by type 3 iodothyronine deiodinase
in infantile hemangiomas.
Selenium as a causative factor for goitre formation has been explained by diminished activity of selenocysteine enzymes in thyroid, notably glutathione peroxidase and deiodinase
type-1 in selenium deficiency (29,30).
She said one of the enzymes that control thyroid hormone levels in the fetal brain is the iodothyronine deiodinase
type III, or Dio3.
T3 is the thyroxine molecule that has lost one iodine atom, due to the action of deiodinase
, a de-iodinating enzyme.
The brain controls its thyroid hormone rather precisely by deiodinazing--with a special deiodinase