Description
T3 Reverse, LC/MS/MS - 3,3`,5`-Triiodothyronine (reverse T3, rT3) is, along with 3,3,5`-Triiodothyronine (T3) a deiodinated metabolite of thyroxine (T4), the major secretory product of the thyroid gland and is secreted into the bloodstream. Unlike T3, however, rT3 is thought to be metabolically inert.
The process of 5`-monodeiodination that converts T4 to T3, and rT3 to diiodothyronine (DTT) is inhibited in a wide variety of conditions, collectively referred to as nonthyroidal illnesses (NTI) or the `euthyroid sick` state. These conditions include fasting, malnutrition, poorly controlled diabetes mellitus, trauma, surgery, and systemic illness. Consequently, in patients with NTI the serum T3 level typically decreases, and the rT3 often, but not always, increases.
Reverse T3 otherwise called 3,3`,5`-triiodothyronine, rT3 is a biologically inactive metabolite of thyroxine produced by the thyroid gland.Reverse T3 is the iodothyronine releases by the thyroid gland into the bloodstream.
The activities of thyroid hormone is regulated by a system of enzymes that activate, inactivate or discard the prohormone T4 and in turn modify T3 and rT3 functionally. rT3 is formed by removal of an iodine atom in the inner ring of T4.Reverse T3 is an inactive form of T3 that will be elevated when the body is under stress.
The levels of rT3 increase in conditions such as euthyroid sick syndrome. Increased rT3 concentrations result from Thyroxine 5-deiodinase activity in critical illness, malnutrition, starvation or fetal growth.
Hypothyroidism is usually characterized by low T3 and low rT3. Unexpected high rise of rT3 can be developed if a person is hypothyroid.
Reference Range(s)
8-25 ng/dL
