Reverse triiodothyronine

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Reverse triiodothyronine
Skeletal formula of reverse triiodothyronine
Ball-and-stick model of the reverse triiodothyronine molecule as a zwitterion
IUPAC name
(2S)-2-Amino-3-[4-(4-hydroxy-3,5-diiodophenoxy)-3-iodophenyl]propanoic acid
3D model (Jmol)
ECHA InfoCard 100.150.134
MeSH Reverse+triiodothyronine
Molar mass 650.974
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Reverse triiodothyronine (3,3’,5’-triiodothyronine, reverse T3, or rT3) is an isomer of triiodothyronine (3,5,3’ triiodothyronine, T3).

Reverse T3 is the third-most common iodothyronine the thyroid gland releases into the bloodstream, of which 0.9% is rT3; tetraiodothyronine (levothyroxine, T4) constitutes 90% and T3 is 9%. However, 95% of rT3 in human blood is made elsewhere in the body, as enzymes remove a particular iodine atom from T4.[1]

The production of hormone by the thyroid gland is controlled by the hypothalamus and pituitary gland. The physiological activity of thyroid hormone is regulated by a system of enzymes that activate, inactivate or simply discard the prohormone T4 and in turn functionally modify T3 and rT3. These enzymes operate under complex direction of systems including neurotransmitters, hormones, markers of metabolism and immunological signals.

The levels of rT3 increase in conditions such as euthyroid sick syndrome because its clearance decreases while its production stays the same. The decreased clearance is possibly from lower 5'-deiodinase activity in the peripheral tissue or decreased liver uptake of rT3.[2]


Synthesis of Reverse T3 from T4 via deiodination. Synthesis of T3 and T2 is also shown.


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