Thyroid Flashcards
define Hashimoto disease
- common cause of hypothyrodism due to autoimmune antibodies directed against thyroglobulin or thyroid peroxidase
- results in low TH productiong (and high circulating TSH) and eventual destruction of thyroid gland
define graves disease
- autoantibodies bind to and stimulate TSH receptors leading to production of EXCESSIVE amounts of thyroid hormones
what is the function of thyroid hormones
- maintain energy homeostasis and regulate energy expenditure
- stimulates carb and fat metabolism
- Thyroid hormone receptors are found virtually in all tissues and located on the nuclei of target cells
what occurs if you have a deficiency of thyroid hormones?
- failure of body growth and mental retardation
- cretinism = extreme hypothyroidism in early life
what does the measure of TSH mean?
- Low TSH could indicate inadequate hypothalamus activity or too much thyroid activity
describe thyroid hormone transport
- thyroid hormones are bound to plasma proteins (THYROXINE-BINDING GLOBULIN or TRANSTHRYRETIN)
- Albumin and lipoproteins also bind and transport thyroid hormones
- free from thyroid hormoens is responsible for neg feedback on pituitary/hypothalamus
define iodide trapping
- after iodide is transported into thyroid epithelial cell, it is concentrated and this is called trapping
define organification
- process of bindign iodine with thyroglobulin
Define Thyroxine-binding prealbumin
specific thyroid binding protein transthyretin
- binds to retinol
thyroglobulin
storage form of T3/T4
thryotropin
TSH = controls synthesis and secretion of thyroid hormones
thyrotropin-releasing hormone (TRH)
- from hypothalamus, causes TSH release from ant. pit
define goiter
- swelling of the thyroid gland
- due to prolonged increases in TSH stimulation of thyroid cause it to enlarge
- also can be caused by deficiency in iodide
- also possibly due to hypothyrodism??
What values do you expect to see in Primary hypothyroidism
- Low T4
- High TRH
- High TSH
What values do you expect to see in pituitary hypothyroidism (secondary)
- Low T4
- High TRH
- Low TSH
What values do you expect to see in hypothalamic hypothyroidism
- Low T4
- Low TRH
- Low TSH
What values do you expect to see in Pituitary hyperthyroidism
- High T4
- Low TRH
- High TSH
What values do you expect to see in graves disease
- High T4
- Low TRH
- Low TSH
