What hormone stimulates T3 T4?
When the level of thyroid hormones (T3 & T4) drops too low, the pituitary gland produces Thyroid Stimulating Hormone (TSH) which stimulates the thyroid gland to produce more hormones. Under the influence of TSH, the thyroid will manufacture and secrete T3 and T4 thereby raising their blood levels.
What stimulates T3 and T4?
thyroid-stimulating hormone: Also known as TSH or thyrotropin, this is a hormone that stimulates the thyroid gland to produce thyroxine (T4), and then triiodothyronine (T3), which stimulates the metabolism of almost every tissue in the body.
How is triiodothyronine T3 produced in the body?
Triiodothyronine is the active form of the thyroid hormone, thyroxine. Approximately 20% of triiodothyronine is secreted into the bloodstream directly by the thyroid gland. The remaining 80% is produced from conversion of thyroxine by organs such as the liver and kidneys.
Where is thyroxine and triiodothyronine produced?
The thyroid gland is essential to the endocrine system. It is located in front of the neck and is responsible for the production of thyroid hormones. The thyroid gland releases triiodothyronine (T3) and thyroxine (T4).
What is the target of thyroid hormone?
| Endocrine gland/ source of hormone | Hormone | Target organ or tissue |
|---|---|---|
| Thyroid | Thyroxine (T4) Triiodothyronine (T3) | Most tissues |
| Calcitonin | Bone | |
| Parathyroids | PTH (parathyroid hormone) | Bone, kidneys, intestine |
| Thymus (regresses in adulthood) | Thymopoetin | T-lymphocyte cells in blood |
How do thyroid hormones affect growth?
In addition to its complex metabolic effects involved in the general mechanisms of body growth, thyroid hormone stimulates the production of growth factors, particularly EGF and NGF. Moreover, it affects GH and somatomedin production and also their tissue activity.
Does thyroid affect height?
Thyroid and Growth in Disease Hypothyroidism is a well-known cause of growth retardation. Height prognosis in children with late-diagnosed congenital hypothyroidism is guarded. Although treatment leads to an initial catch-up growth spurt, prolonged hypothyroidism may result in compromised adult height (48).