Thyroid Hormones and Their Functions

Thyroid Hormones

• Thyroid hormones are produced by the thyroid gland and play a crucial role in regulating metabolism, growth, and development.
• The two main thyroid hormones are triiodothyronine (T3) and thyroxine (T4).

Functions of Thyroid Hormones

• Regulate metabolic rate and energy expenditure
• Influence growth and development, particularly in children and adolescents
• Play a role in the regulation of body temperature

Hypothyroidism

• A condition characterized by underactive thyroid gland, resulting in insufficient production of thyroid hormones
• Symptoms include fatigue, weight gain, dry skin, and hair loss
• Treatment involves replacement therapy with synthetic thyroid hormones (e.g., levothyroxine)

Hyperthyroidism

• A condition characterized by overactive thyroid gland, resulting in excessive production of thyroid hormones
• Symptoms include weight loss, anxiety, heat intolerance, and rapid heartbeat
• Treatment involves reducing thyroid hormone production using antithyroid drugs or radioactive iodine therapy

Antithyroid Drugs

• Medications used to treat hyperthyroidism by reducing thyroid hormone production
• Examples of antithyroid drugs include methimazole and propylthiouracil
• These drugs work by inhibiting the production of thyroid hormones or blocking their release from the thyroid gland

Action of Antithyroid Drugs

• Methimazole: inhibits the enzyme thyroid peroxidase, reducing thyroid hormone synthesis
• Propylthiouracil: inhibits the enzyme thyroid peroxidase and also blocks the peripheral conversion of T4 to T3