27.1 Introduction to the Thyroid and Parathyroid
2 min read•june 18, 2024
The thyroid and play crucial roles in regulating metabolism and calcium balance. Thyroid hormones control your body's energy use, while manages calcium levels in your blood and bones.
Understanding these glands is key for nurses. You'll need to recognize symptoms of thyroid disorders, like fatigue or anxiety, and know how to interpret lab tests. This knowledge helps you provide better care for patients with endocrine issues.
Thyroid and Parathyroid Glands
Thyroid and parathyroid hormone roles
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- Thyroid hormones T3 and T4 regulate metabolism by increasing basal metabolic rate (BMR), stimulating carbohydrate and fat metabolism, increasing protein synthesis and breakdown, and enhancing growth and development
- regulates calcium balance by increasing serum calcium levels through stimulating osteoclasts to release calcium from bones, enhancing calcium reabsorption in the kidneys, and activating vitamin D to increase calcium absorption in the intestines, while also decreasing serum phosphate levels by inhibiting renal reabsorption
Hypothyroidism and hyperthyroidism symptoms and causes
- (underactive thyroid) symptoms include fatigue, weight gain, cold intolerance, dry skin, hair loss, constipation, bradycardia, hypothermia, delayed reflexes, depression, and memory impairment, caused by autoimmune disorders (), iodine deficiency, surgical removal or radiation therapy of the , or certain medications (lithium, amiodarone)
- (overactive thyroid) symptoms include nervousness, anxiety, irritability, heat intolerance, increased sweating, tachycardia, palpitations, tremors, weight loss despite increased appetite, diarrhea, and menstrual irregularities, caused by autoimmune disorders (), thyroid nodules or , excessive iodine intake, or (inflammation of the )
Diagnostic tests for thyroid and parathyroid function
- Thyroid function tests include:
- Thyroid-stimulating hormone (TSH): elevated in hypothyroidism, decreased in hyperthyroidism
- Free T4 (): decreased in hypothyroidism, elevated in hyperthyroidism
- Free T3 (): may be decreased in hypothyroidism or elevated in hyperthyroidism
- Thyroid antibodies (, ): presence indicates autoimmune thyroid disorders
- Parathyroid function tests include:
- Serum calcium: elevated in , decreased in
- Serum phosphate: decreased in hyperparathyroidism, elevated in hypoparathyroidism
- Parathyroid hormone (PTH): elevated in primary hyperparathyroidism, decreased in hypoparathyroidism
- 24-hour urine calcium: increased in hyperparathyroidism, decreased in hypoparathyroidism
Key Terms to Review (47)
Anterior Pituitary Gland: The anterior pituitary gland is the front, or anterior, lobe of the pituitary gland, a small, pea-sized endocrine gland located at the base of the brain. It is responsible for producing and secreting various hormones that regulate important physiological processes in the body, including thyroid function and the female reproductive system.
Anti-Thyroglobulin: Anti-thyroglobulin is an autoantibody that targets thyroglobulin, a protein produced by the thyroid gland. It is an important marker in the assessment and management of thyroid disorders, particularly autoimmune thyroid diseases like Hashimoto's thyroiditis and Graves' disease.
Anti-TPO: Anti-TPO, or anti-thyroid peroxidase antibodies, are autoantibodies that target the thyroid peroxidase enzyme, which is essential for the production of thyroid hormones. These antibodies are a key marker for autoimmune thyroid disorders, such as Hashimoto's thyroiditis and Graves' disease.
C Cells: C cells, also known as parafollicular cells, are a type of specialized endocrine cells found within the thyroid gland. These cells are responsible for the production and secretion of the hormone calcitonin, which plays a crucial role in the regulation of calcium and phosphate homeostasis in the body.
Calcimimetics: Calcimimetics are drugs that mimic the action of calcium on tissues, particularly by binding to and activating the calcium-sensing receptors (CaSR) on the parathyroid gland. This leads to a decrease in parathyroid hormone (PTH) secretion.
Calcitonin: Calcitonin is a hormone produced by the thyroid gland that helps regulate calcium levels in the blood. It lowers blood calcium levels by inhibiting osteoclast activity and increasing calcium excretion in the kidneys.
Calcitonin: Calcitonin is a hormone produced by the thyroid gland that plays a crucial role in the regulation of calcium and phosphate homeostasis within the body. It functions to lower blood calcium levels and promote the deposition of calcium into bones, making it an important factor in the topics of electrolytes, thyroid and parathyroid function, as well as the management of conditions related to calcium and bone metabolism.
Calcium Homeostasis: Calcium homeostasis is the physiological process that regulates the concentration of calcium in the blood and extracellular fluids. It is essential for maintaining proper muscle function, nerve transmission, and bone health, and is closely tied to the functioning of the thyroid, parathyroid, and other endocrine systems.
Calcium-Sensing Receptor: The calcium-sensing receptor (CaSR) is a G protein-coupled receptor that plays a crucial role in the regulation of calcium homeostasis in the body. It acts as a molecular sensor, detecting changes in extracellular calcium levels and triggering appropriate physiological responses to maintain calcium balance.
Chvostek sign: Chvostek sign is a clinical indicator of hypocalcemia, where tapping the facial nerve leads to twitching of facial muscles. It is commonly used to assess neuromuscular excitability.
Deiodinase: Deiodinase is an enzyme that catalyzes the removal of iodine atoms from thyroid hormones, playing a crucial role in the regulation of thyroid hormone metabolism and activation within the body. This enzyme is essential for maintaining proper thyroid function and overall metabolic homeostasis.
Diagnostic testing: Diagnostic testing involves a variety of medical tests used to identify the presence and cause of a thyroid or parathyroid disorder. These tests are crucial for determining appropriate treatment options.
Exophthalmos: Exophthalmos, also known as proptosis, is the abnormal protrusion or bulging of the eyeball out of the eye socket. This condition is often associated with thyroid disorders, particularly Graves' disease, and can have significant impacts on vision and eye health.
Goiter: A goiter is an abnormal enlargement of the thyroid gland. It can result from iodine deficiency, autoimmune diseases, or other thyroid disorders.
Goiter: A goiter is an abnormal enlargement of the thyroid gland, often resulting from an iodine deficiency or other underlying thyroid disorders. This condition can affect the body's ability to produce and regulate thyroid hormones, which are essential for metabolism, growth, and development.
Graves’ disease: Graves' disease is an autoimmune disorder that causes hyperthyroidism, where the thyroid gland produces too much thyroid hormone. It is characterized by symptoms such as rapid heartbeat, weight loss, and bulging eyes.
Graves' Disease: Graves' disease is an autoimmune disorder that causes the thyroid gland to overproduce thyroid hormones, leading to a condition known as hyperthyroidism. It is the most common cause of hyperthyroidism and is associated with specific symptoms and complications.
Hashimoto thyroiditis: Hashimoto thyroiditis is an autoimmune disorder where the immune system attacks the thyroid gland, leading to hypothyroidism. It is the most common cause of hypothyroidism in iodine-sufficient areas.
Hashimoto's Thyroiditis: Hashimoto's thyroiditis is an autoimmune disorder in which the immune system mistakenly attacks and damages the thyroid gland, leading to hypothyroidism. It is the most common cause of hypothyroidism in iodine-sufficient areas of the world.
Hyperparathyroidism: Hyperparathyroidism is a condition characterized by excessive production of parathyroid hormone (PTH) by the parathyroid glands. This leads to elevated levels of calcium in the blood, which can affect various bodily functions.
Hyperthyroidism: Hyperthyroidism is a condition in which the thyroid gland produces an excessive amount of thyroid hormones, leading to an overactive metabolism. This imbalance can have significant impacts on various bodily functions and is an important consideration in the context of hormonal therapy, potassium channel blockers, and thyroid-related disorders.
Hypoparathyroidism: Hypoparathyroidism is a condition characterized by insufficient production of parathyroid hormone (PTH), leading to low levels of calcium in the blood. It typically results from damage or removal of the parathyroid glands.
Hypothyroidism: Hypothyroidism is a condition in which the thyroid gland produces an insufficient amount of thyroid hormones, leading to a slowing of various metabolic processes in the body. This term is relevant across multiple topics, including osmolality, vitamins and minerals, mood stabilizers, potassium channel blockers, growth hormones, thyroid and parathyroid functions, thyroid and antithyroid drugs, and weight management.
Iodine Uptake: Iodine uptake refers to the process by which the thyroid gland actively absorbs and concentrates iodine from the bloodstream. This is a crucial step in the production of thyroid hormones, which are essential for regulating metabolism, growth, and development in the body.
Levothyroxine: Levothyroxine is a synthetic thyroid hormone used to treat hypothyroidism, a condition where the thyroid gland does not produce enough thyroid hormones. It is the primary treatment for an underactive thyroid and helps restore normal thyroid function by supplementing the body's natural thyroid hormones.
Myxedema coma: Myxedema coma is a severe, life-threatening form of hypothyroidism characterized by decreased mental status, hypothermia, and multiple organ dysfunction. It requires immediate medical intervention to prevent mortality.
Negative Feedback Loop: A negative feedback loop is a regulatory mechanism in biological systems where the output of a process acts to reduce or inhibit further changes in that output. This process helps maintain homeostasis and balance within the body's physiological systems.
Parathyroid Glands: The parathyroid glands are a group of four small endocrine glands located behind the thyroid gland in the neck. These glands are responsible for producing parathyroid hormone (PTH), which plays a crucial role in regulating calcium and phosphate levels in the body, as well as maintaining bone health. The parathyroid glands are closely connected to the topics of thyroid function and calcium homeostasis.
Parathyroid Hormone: Parathyroid hormone (PTH) is a peptide hormone secreted by the parathyroid glands that plays a crucial role in regulating calcium and phosphate homeostasis within the body. It is closely connected to the topics of thyroid and parathyroid function, as well as various calcium-related therapies and medications.
Parathyroid hormone (PTH): Parathyroid hormone (PTH) is a hormone produced by the parathyroid glands that regulates calcium and phosphate levels in the blood. It plays a critical role in bone metabolism and calcium homeostasis.
Radioactive Iodine Uptake Test: The radioactive iodine uptake (RAIU) test is a diagnostic procedure used to evaluate the function of the thyroid gland. It measures the amount of radioactive iodine the thyroid gland absorbs from the bloodstream, providing information about the gland's ability to produce thyroid hormones.
Thyroglobulin: Thyroglobulin is a large glycoprotein produced by the thyroid gland that serves as the precursor for the production of the thyroid hormones triiodothyronine (T3) and thyroxine (T4). It plays a crucial role in the regulation of thyroid function and the maintenance of overall metabolic processes in the body.
Thyroid Follicles: Thyroid follicles are the functional units of the thyroid gland, responsible for the production and storage of thyroid hormones. These spherical structures are lined with a single layer of thyroid epithelial cells and contain a colloid-filled central lumen, where thyroid hormones are synthesized and stored.
Thyroid gland: The thyroid gland is a butterfly-shaped endocrine gland located in the neck that produces hormones regulating metabolism, growth, and development. It primarily secretes thyroxine (T4) and triiodothyronine (T3).
Thyroid Gland: The thyroid gland is an endocrine gland located in the front of the neck that produces hormones essential for regulating metabolism, growth, and development. It plays a crucial role in the body's overall homeostasis and is closely connected to the topics of Introduction to the Thyroid and Parathyroid, as well as Thyroid and Antithyroid Drugs.
Thyroid Peroxidase: Thyroid peroxidase is an enzyme that plays a crucial role in the production of thyroid hormones. It catalyzes the oxidation of iodide to iodine, which is then incorporated into the thyroid hormones thyroxine (T4) and triiodothyronine (T3) within the thyroid gland.
Thyroid storm (thyrotoxic crisis): Thyroid storm, or thyrotoxic crisis, is a life-threatening condition characterized by an extreme overproduction of thyroid hormones. It often results from untreated or poorly managed hyperthyroidism and requires immediate medical intervention.
Thyroid-Binding Globulin: Thyroid-binding globulin (TBG) is a transport protein produced by the liver that binds and carries thyroid hormones, such as thyroxine (T4) and triiodothyronine (T3), in the bloodstream. It plays a crucial role in the regulation and distribution of these essential hormones throughout the body.
Thyroid-Stimulating Hormone Test: The thyroid-stimulating hormone (TSH) test is a blood test used to measure the level of TSH, a hormone produced by the pituitary gland that regulates the function of the thyroid gland. This test is a crucial diagnostic tool for evaluating thyroid disorders, such as hypothyroidism and hyperthyroidism.
Thyroidectomy: A thyroidectomy is a surgical procedure that involves the partial or complete removal of the thyroid gland, a small, butterfly-shaped endocrine gland located at the base of the neck. This procedure is typically performed to treat various thyroid-related conditions, including thyroid cancer, thyroid nodules, and hyperthyroidism.
Thyroiditis: Thyroiditis is a general term that refers to inflammation of the thyroid gland. It can be caused by various factors, including autoimmune disorders, viral infections, or radiation exposure, and can lead to changes in thyroid hormone production and function.
Thyroxine: Thyroxine, also known as T4, is a hormone produced by the thyroid gland that plays a crucial role in regulating the body's metabolism, growth, and development. It is the primary thyroid hormone secreted by the thyroid gland and is essential for maintaining homeostasis in the body.
Thyroxine (T4): Thyroxine (T4) is a hormone produced by the thyroid gland that plays a crucial role in metabolism, growth, and development. It is converted to the more active form, triiodothyronine (T3), in tissues.
Toxic Multinodular Goiter: Toxic multinodular goiter is a condition characterized by the development of multiple nodules within the thyroid gland, leading to the overproduction of thyroid hormones and subsequent hyperthyroidism. This condition is often associated with the gradual enlargement of the thyroid gland over time.
Triiodothyronine: Triiodothyronine, also known as T3, is a thyroid hormone that plays a crucial role in regulating the body's metabolism, growth, and development. It is one of the two main thyroid hormones, the other being thyroxine (T4).
Triiodothyronine (T3): Triiodothyronine (T3) is a thyroid hormone that plays crucial roles in metabolism, growth, and development. It is more potent than thyroxine (T4) and exerts significant effects on nearly every physiological process in the body.
Trousseau sign: Trousseau sign is a clinical indication of latent tetany in which carpal spasm occurs after occlusion of the brachial artery with a blood pressure cuff. It is often associated with hypocalcemia and disorders affecting calcium metabolism.