T3 TOTAL
- Code
- 600.3537
- Name
- T3 TOTAL
- Category
- None
- Department
- Chemistry
- Start Date
- Expiration Date
- Synonyms
- Triiodothyronine; Total; Total T3
- CPT Codes
- 84480
- Site
- Main Lab
- Reference Test
Specimen Information
- Type
Gold, SST
- Volume
1.0 ml
- Transport Info
Refrigerated
48 hour stability- Fasting Required?
- False
- Patient Instructions
- Reference Range
0.87-1.78 ng/mL
- Methodology
Chemiluminescence
Clinical Significance
Utilized in the diagnosis of T3-hyperthyroidism, the detection of early stages of hyperthyroidism and for indicating a diagnosis of thyrotoxicosis factitia.
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 fall 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 the “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.