Specimen Type: Serum
Container: 1 Serum Separator Tube (SST)
Preferred Vol: 1.00 mL
Min Vol: 0.50 mL
Liquid Chromatography/Tandem Mass Spectrometry (LC-MS-MS)
Sunday - Friday
3,3',5'-Triiodothyronine (reverse T3, rT3) is, along with 3,3,5'-Triio dothyronine (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 (DIT) is inhibited in a wide variety of conditions, including fasting, malnutrition, poorly controlled diabetes mellitus, trauma, surgery, and systemic illness. Consequently, the serum T3 level typically decreases, and the rT3 often, but not always, increases in these circumstances.