About Triiodothyronine (T3) Free
Free Triiodothyronine (T3) is one of the primary hormones produced by the thyroid gland. It plays a crucial role in the body's metabolic processes, including regulating the heart rate, body temperature, and how the body metabolizes nutrients. Unlike total T3, free T3 levels are not bound to proteins in the blood, providing a more accurate reflection of the hormone that is active in the tissues.
Reference Values
Optimal Range
2.3 - 4.2 pg/mL
Women's Optimal Range
2.3 - 4.2 pg/mL
Elite Value
Not specified
Health Implications
High
Elevated levels may indicate hyperthyroidism, leading to symptoms such as weight loss, heart palpitations, and anxiety.
Low
Low levels may be associated with hypothyroidism, which can cause fatigue, weight gain, and depression.
Symptoms
High
May include anxiety, increased heart rate, insomnia, weight loss, and heat intolerance.
Low
Can include fatigue, weight gain, depression, cold intolerance, and dry skin.
Lifestyle Factors
Specimen Type
Testing Methods
Also Known As
Scientific Sources
- 1. Biondi, B., & Wartofsky, L. (2021). Treatment with thyroid hormone. Endocrine Reviews, 42(1), 64-110. 2. Ross, D. S., Burch, H. B., Cooper, D. S., Greenlee, M. C., Laurberg, P., Maia, A. L., ... & Walter, M. A. (2016). 2016 American Thyroid Association guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid, 26(10), 1343-1421. 3. Jonklaas, J., Bianco, A. C., Bauer, A. J., Burman, K. D., Cappola, A. R., Celi, F. S., ... & Wartofsky, L. (2014). Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association task force on thyroid hormone replacement. Thyroid, 24(12), 1670-1751. 4. Chaker, L., Bianco, A. C., Jonklaas, J., & Peeters, R. P. (2017). Hypothyroidism. The Lancet, 390(10101), 1550-1562. 5. Fliers, E., Klieverik, L. P., & Kalsbeek, A. (2010). Novel neural pathways for metabolic effects of thyroid hormone. Trends in Endocrinology & Metabolism, 21(4), 230-236.