T3, Reverse, LC/MS/MS : 90963

T3RLCQ or 90963

RT3, Triiodothyronine Reverse, rT3, Reverse Triiodothyronine, Reverse T3, T3 Reverse

Plain red, serum separator tube, green (no gel) (sodium heparin), or lavender (EDTA) tube.

Allow blood to clot at room temperature for 30 minutes. Centrifuge and separate the serum from cells within 24 hours of collection. Alternatively, collect blood in a gel barrier tube, allow to clot at room temperature, centrifuge and remove from gel within 24 hours. If green (no gel) sodium heparin or lavender (EDTA) tube, centrifuge to separate from cells within 24 hours of collection.  After centrifugation immediately aliquot 0.5 mL (Min: 0.3 mL) serum or plasma into a standard transport tube.

Refrigerated.

Ambient: 7 days; Refrigerated: 7 days; Frozen: 30 days

Unseparated serum or plasma, Serum in Serum Separator Tube (SST) not separated from the gel within 24 hours.

Sunday - Saturday

2-4 days (From receipt at performing laboratory)

8-25 ng/dL

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 (DIT) 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.