Endocrinology - Thyroid Gland Review

Flashcards for Endocrinology exam review focusing on thyroid anatomy, hormone synthesis, and related disorders.

Thyroid Gland

Located in the lower anterior neck, shaped like a butterfly, with two lobes resting on either side of the trachea.

Isthmus

Band of tissue that runs anterior to the trachea and bridges the two lobes of the thyroid gland.

Parathyroid Glands

Glands located posterior to the thyroid that regulate serum calcium levels.

Follicular Cells

Cells in the thyroid responsible for synthesizing thyroid hormones.

Parafollicular (C) Cells

Cells in the thyroid responsible for synthesizing calcitonin.

Follicle

Basic unit of the thyroid gland, containing colloid in the center.

Thyroglobulin (Tg)

Glycoprotein that is the major component of colloid and rich in tyrosine.

Follicles

Site of thyroid protein synthesis

Iodine

Essential component of thyroid hormone, obtained from seafood, dairy, and other sources.

Hypothyroidism (due to iodine deficiency)

Condition resulting from iodine intake less than 50 μg/day, leading to mental delays and stunted growth.

Thyroxine (T4)

Thyroid hormone that is main form secreted.

Triiodothyronine (T3)

Thyroid hormone that is the main active form.

Thyroid Peroxidase (TPO)

Enzyme that helps combine DIT and MIT molecules to form T4 and T3.

Thyroid-Stimulating Hormone (TSH)

Hormone from the pituitary that regulates thyroid hormone synthesis.

Goiter

Condition caused by prolonged TSH stimulation leading to increased vascularity and hypertrophic enlargement of the thyroid gland.

Thyroid Hormone

Hormone critical in regulating body metabolism, neurologic development, and other body functions.

Free T3/T4

Only small percentage of T3 and T4 are available for hormonal activity when released into circulation.

Thyroxine-Binding Globulin (TBG)

Binding protein: major carrier protein for thyroid hormones in the blood.

Thyrotropin-Releasing Hormone (TRH)

Hormone from the hypothalamus that stimulates the pituitary to release TSH.

Thyroid-Stimulating Hormone (TSH) Assay

Type of blood test useful for assessing thyroid function.

Thyroglobulin (Tg)

Ideal tumor marker for effectively treated thyroid cancer patients.

Thyroid Peroxidase Antibody (TPOAb)

Antibody most often tested to evaluate thyroid autoimmune diseases

Hashimoto’s Thyroiditis

Autoimmune disease (a form of hypothyroidism) that requires a test to detect thyroid peroxidase antibodies.

Hypothyroidism

One of the most common disorders of the thyroid gland, especially in women over 65.

Hashimoto's Thyroiditis

Most common cause of hypothyroidism in developed countries, targeting the thyroid gland.

Myxedema

Advanced stage of hypothyroidism, referring to the deposition of mucopolysaccharides in the skin.

Thyrotoxicosis

Excess of thyroid hormone in peripheral tissues.

Graves’ Disease

Most common cause of thyrotoxicosis; an autoimmune disease that stimulates thyroid hormone production.

Toxic Adenoma and Multinodular Goiter

Two common causes of hyperthyroidism caused by autonomously functioning thyroid tissue.

Cretinism

Hypothyroidism occurring in infancy