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Adrenal cortical carcinoma
Primary adrenal insufficiency
Congenital adrenal hyperplasia
Multiple endocrine neoplasia
Opsoclonus myoclonus syndrome (NORD)
Pancreatic neuroendocrine neoplasms
Androgen insensitivity syndrome
Polycystic ovary syndrome
Premature ovarian failure
Constitutional growth delay
Growth hormone deficiency
Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Autoimmune polyglandular syndrome type 1 (NORD)
Thyroglossal duct cyst
Thyroid eye disease (NORD)
Toxic multinodular goiter
Euthyroid sick syndrome
Subacute granulomatous thyroiditis
Adrenal insufficiency: Pathology review
Adrenal masses: Pathology review
Cushing syndrome and Cushing disease: Pathology review
Diabetes insipidus and SIADH: Pathology review
Diabetes mellitus: Pathology review
Hyperthyroidism: Pathology review
Hypopituitarism: Pathology review
Hypothyroidism: Pathology review
Multiple endocrine neoplasia: Pathology review
Neuroendocrine tumors of the gastrointestinal system: Pathology review
Parathyroid disorders and calcium imbalance: Pathology review
Pituitary tumors: Pathology review
Thyroid nodules and thyroid cancer: Pathology review
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Patient Journeys Hypothyroidism Alison
Hypothalamic & Pituitary Dysfunction - Clinical Manifestations
Hypothalamic & Pituitary Dysfunction - Etiologies
Hypothyroidism: Other Causes
Hypothyroidism: Overview & Hashimoto's Thyroiditis
hypothyroidism p. 248
hypothyroidism with p. 345
maternal hypothyroidism from p. 345
amiodarone and p. 327
anemia p. 426
in anemia taxonomy p. 423
carpal tunnel syndrome and p. 452
as drug reaction p. 248
hormone replacement p. 360
lithium p. 594
hypothyroidism p. 345
hypothyroidism in p. 346
In hypothyroidism, ‘hypo' refers to having too little, and ‘thyroid’ refers to thyroid hormone, so hypothyroidism refers to a condition where there’s a lack of thyroid hormones.
Normally, the hypothalamus, which is located at the base of the brain, detects low blood levels of thyroid hormones and releases thyrotropin-releasing hormone into the hypophyseal portal system - which is a network of capillaries linking the hypothalamus to the anterior pituitary.
The anterior pituitary then releases thyroid-stimulating hormone, also called thyrotropin or simply TSH.
TSH stimulates the thyroid gland which is a gland located in the neck that looks like two thumbs hooked together in the shape of a “V”.
The thyroid gland is made up of thousands of follicles, which are small spheres lined with follicular cells. Follicular cells convert thyroglobulin, a protein found in follicles, into two iodine-containing hormones, triiodothyronine or T3, and thyroxine or T4.
Once released from the thyroid gland, these hormones enter the blood and bind to circulating plasma proteins.
Only a small amount of T3 and T4 will travel unbound in the blood, and these two hormones get picked up by nearly every cell in the body.
Once inside the cell T4 is mostly converted into T3, and it can exert its effect. T3 speeds up the cell’s basal metabolic rate.
So as an example, the cell might produce more proteins and burn up more energy in the form of sugars and fats. It’s as if the cells are in a bit of frenzy.
T3 increases cardiac output, stimulates bone resorption - thinning out the bones, and activates the sympathetic nervous system, the part of the nervous system responsible for our ‘fight-or-flight’ response.
Hypothyroidism refers to a condition where there's a lack of thyroid hormones (triiodothyronine (T3) and thyroxine (T4)), which normally help control the body's metabolism.
Hypothyroidism can be primary or secondary. In primary hypothyroidism, the thyroid gland isn't working properly, because of an autoimmune disease like Hashimoto's thyroiditis, hyperthyroidism treatment, or a congenital defect. In secondary hypothyroidism, either the anterior pituitary gland or the hypothalamus is the problem, usually because of a tumor or damage from surgery.
Symptoms of Hypothyroidism include weight gain, mental slowness, swelling in the skin and soft tissues, and a slower heart rate.
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