Reach out! We’re available by email or phone and can answer all of your questions.
You can also reference the ordering page for more information.
- Sample Types Urine, Tissue Culture Media, Extracted Serum, Plasma, and Fecal Extracts
- Species T3 is identical across species
- Sensitivity 37.4 pg/mL
- Time to Answer 2.5 Hours
- Samples/Kit 39 or 231 in Duplicate
- Readout Colorimetric, 450 nm
- Standard Curve
Triiodothyronine, also known as T3, is a thyroid hormone. Thyroid hormones regulate a number of developmental, metabolic, and neural activities throughout the body. T3 affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate. Production of T3 and its prohormone, thyroxine (T4), is activated by thyroid-stimulating hormone (TSH), which is released from the pituitary gland. This pathway is part of a closed-loop feedback process when elevated concentrations of T3 and T4 in the blood inhibit the production of TSH in the pituitary gland. As concentrations of these hormones decrease, the pituitary gland increases production of TSH, and by these processes, a feedback control system stabilizes the amount of thyroid hormones in 100 1.0 the bloodstream. The concentration of serum T4 is 20 times that of T3.
Circulating levels of T4 are much greater than T3 levels, but T3 is the more metabolically active hormone (3-4 times more potent than T4) although its effect is briefer due to its shorter half-life. In hyperthyroidism, both T4 and T3 levels are usually elevated, but in a small subset of hyperthyroid patients only T3 is elevated (T3 toxicosis). Triiodothyronine values greater than 2 ng/mL in adults, or children, are consistent with hyperthyroidism or high thyroid hormone-binding proteins. In hypothyroidism, T4 and T3 levels are decreased. T3 levels are frequently low in sick or hospitalized euthyroid patients.