The follicular cells of the thyroid gland synthesize two thyroid hormones; Tetraiodothyronine (T
-Thyroxine) and triiodothyronine (T
) and the C-cells of thyroid gland produces Thyrocalcitonin. The function of these hormones are as follows
- Thyroxine is the main hormone (80% in thyroxine form) secreted into the bloodstream by the thyroid gland.
- It is the inactive form and most of it is converted to an active form called as triiodothyronine (T) by organs such as the liver and kidneys.
- Both T and T are synthesized from tyrosine and iodine.
- The thyroid hormones control the metabolism of carbohydrates, protein and fats. They play an important role in regulating the Basal Metabolic Rate (BMR)
- They are also important for maintenance of water and electrolyte balance.
- Thyroid hormones also regulate the RBC production.
- The thyrocalcitonin maintains the blood calcium levels and promotes the bone formation.