T4 to T3

[croc345]

Hi..how long after taking levo..T4. ..is it converted to T3..

[radd]

croc,

This is so variable from person to person as depends on multifactoral processes.

T4 is converted into T3 by the deiodinase system (D1, D2, D3) in multiple tissues and organs, but especially in the liver, gut, skeletal muscle, brain and the thyroid gland itself. The rate of conversion will be influenced by ill health in any of these areas … ie the more ill you are, the more likely you are to have issues that may inhibit these processes from taking place.

T3 (and T4) is carried around the body on transport proteins produced in the liver (thyroid binding globulin (TBG), transthretin and albumin) but again poor liver health, other hormone imbalances or poor detoxification will influence how well these work and whether the thyroid hormone can actually be cleaved from their protein carriers to become “free” & bind to thyroid hormone receptors (so becoming active)..

When TSH acts on the thyroid gland (when healthy) it produces a little triiodothyronine (T3) itself. Some T4 will also be converted to reverse T3 to balance or because an excess of T4 is not being utilised properly within the body.

[croc345 in reply to radd]

Wow...what an answer radd...I've read it 3 times...the body system so complex...its amazing. ..