00:00 / 00:00
0 / 17 complete
0 / 9 complete
|Creatine kinase (CK)||145 U/L|
|Aspartate aminotransferase||66 U/L|
|Alanine aminotransferase||77 U/L|
hypothyroidism p. 250
hypothyroidism with p. 347
maternal hypothyroidism from p. 347
amiodarone and p. 329
anemia p. 428
in anemia taxonomy p. 425
carpal tunnel syndrome and p. 456
as drug reaction p. 250
hormone replacement p. 362
lithium p. 598
hypothyroidism p. 347
hypothyroidism in p. 348
hypothyroidism p. 250
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.
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 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.
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