Thyroxine (T4)

Definition

Thyroxine (T4) is a hormone produced by the thyroid gland that plays a crucial role in regulating metabolism, heart rate, and development. It is one of the primary hormones involved in maintaining endocrine health across the lifespan.

5 Must Know Facts For Your Next Test

1. Thyroxine (T4) is converted into its active form, triiodothyronine (T3), within cells to exert its metabolic effects.
2. Adequate levels of iodine in the diet are essential for the synthesis of thyroxine (T4).
3. Hypothyroidism, a condition characterized by low levels of T4, can lead to symptoms such as weight gain, fatigue, and depression.
4. Nutritional deficiencies, particularly in iodine and selenium, can impair T4 production and conversion to T3.
5. Thyroxine plays an important role in growth and development during infancy and childhood.

Review Questions

• What is thyroxine (T4) and what role does it play in the body?
• How does dietary iodine affect thyroxine (T4) synthesis?
• What are some potential consequences of hypothyroidism due to low T4 levels?

Related terms

Triiodothyronine (T3): One of the active thyroid hormones derived from thyroxine (T4) that regulates metabolism.

Hypothyroidism:

A condition where there is insufficient production of thyroid hormones leading to metabolic slowdown.

Iodine:

An essential mineral needed for the synthesis of thyroid hormones including thyroxine (T4).