Total T3

TT3

T3S T3 Triiodothyroxine
 

1.0 mL collected in a SST (serum seprator-gold top tube)

0.5 mL

Plasma - Li Heparin (PST)
Plasma- Na Heparin
Plasma –EDTA (Lavender)
Gold top (SST)
Tiger top (SST)
Red top

Room temperature

Room temperature: 8 days at 20-24ºC
Refrigerated: 14 days at 2-8°C
Frozen: 12 months at ­20°C, Freeze only once.

Samples not labeled with complete first and last name and date of birth.
Grossly hemolyzed.

Sun - Sat

Daily

0.80 – 2.00 ng/mL

Triiodothyronine (T3) is the hormone principally responsible for the development of the effects of the thyroid hormones on the various target organs. T3 (3,5,3'-triiodothyronine) is mainly formed extrathyroidally, particularly in the liver, by enzymatic 5'-deiodination of T4. Accordingly, the T3 concentration in serum is more a reflection of the functional state of the peripheral tissue than the secretory performance of the thyroid gland. A reduction in the conversion of T4 to T3 results in a decrease in the T3 concentration. It occurs under the influence of medicaments such as propanolol, glucocorticoids or amiodarone and in severe non-thyroidal illness (NTI), and is referred to as “low T3 syndrome”. As with T4, over 99 % of T3 is bound to transport proteins. However, the affinity of T3 to them is around 10-fold lower.
The determination of T3 is utilized in the diagnosis of T3-hyperthyroidism, the detection of early stages of hyperthyroidism and for indicating a diagnosis of thyrotoxicosis factitia.