Thyroide

Key Concepts

The thyroid gland produces two main hormones: triiodothyronine (T3) and thyroxine (T4). T3 is the more active form of thyroid hormone, responsible for regulating metabolic rate, growth, and development. T4 is converted to T3 in peripheral tissues.

Thyroid function is regulated by a complex feedback loop involving the hypothalamic-pituitary-thyroid axis (HPT axis). The HPT axis involves the release of thyroid-stimulating hormone (TSH) from the pituitary gland, which stimulates the thyroid gland to produce and secrete T4.

Thyroid disorders can be classified into three main categories: hypothyroidism, hyperthyroidism, and euthyroidism. Hypothyroidism occurs when the thyroid gland does not produce enough T4 and T3, while hyperthyroidism occurs when the gland produces excessive amounts of these hormones.

Technical Details

The thyroid gland is composed of follicles that contain colloid, a protein-rich substance that stores thyroid hormones. The gland is surrounded by a connective tissue capsule and has a rich blood supply.

The average human thyroid gland weighs approximately 20-25 grams and measures about 4 cm in length. It is situated in the neck, below the larynx, and can be felt as a smooth, firm lump during physical examination.

Thyroid function tests (TFTs) are used to diagnose and monitor thyroid disorders. Common TFTs include serum TSH, free T4, free T3, thyroxine-binding globulin (TBG), and triiodothyronine uptake.

Applications/Uses

The thyroid gland plays a crucial role in regulating metabolism, growth, and development. Thyroid hormones are essential for maintaining normal body temperature, heart rate, and energy levels.

Thyroid disorders can have significant impacts on overall health and quality of life. Hypothyroidism can lead to fatigue, weight gain, dry skin, and hair loss, while hyperthyroidism can cause anxiety, tremors, and weight loss.

Treatment options for thyroid disorders include medications, radioactive iodine therapy, and surgery. Medications such as levothyroxine (T4) are commonly used to treat hypothyroidism, while medications like methimazole (MMI) are used to treat hyperthyroidism.

Impact/Significance

Thyroid disorders can have significant impacts on overall health and quality of life. Untreated or undertreated thyroid disorders can lead to complications such as osteoporosis, atherosclerosis, and infertility.

The thyroid gland also plays a crucial role in regulating metabolism and energy levels. Hypothyroidism can lead to fatigue, lethargy, and decreased productivity, while hyperthyroidism can cause anxiety, irritability, and insomnia.

Related Topics

The hypothalamic-pituitary-thyroid axis (HPT axis) is a complex feedback loop that regulates thyroid function. The HPT axis involves the release of thyroid-stimulating hormone (TSH) from the pituitary gland, which stimulates the thyroid gland to produce and secrete T4.

Thyroid disorders can be inherited in an autosomal dominant or recessive pattern, depending on the genetic mutation involved. Genetic testing is available for some thyroid disorders, such as congenital hypothyroidism.