MCQ IN MEDICINE

Detailed explanation-1: -The majority of our T3 however comes from a process called deiodination, which takes place in our peripheral tissues (such as the liver and kidney) via the activity of two enzymes called deiodinase 1 and 2. During this process, an iodine molecule is removed from the hormone T4, converting it into its active form, T3.

Detailed explanation-2: -T4 is converted to T3 in the liver and many other tissues by the action of T4 monodeiodinases. Some T4 and T3 is conjugated with glucuronide and sulfate in the liver, excreted in the bile, and partially hydrolyzed in the intestine. Some T4 and T3 formed in the intestine may be reabsorbed.

Detailed explanation-3: -DIO3 catalyzes the conversion of T4 to rT3 and T3 to 3, 3′-diiodothyronine (T2), both of which are biologically inactive. DIO3 is the main deiodinase during the embryonic period and in developing tissues, protecting developing tissues from excessive TH production.