4 Thyroid Flashcards
what is T4?
thyroxine
what is T3?
triiodothyronine
what do T4 and T3 do?
stimulates metabolism of all cells
what does calcitonin do?
decreased blood calcium concentration by inhibiting breakdown of bone
how is T3 and T4 released?
TRH by hypothalamus which act on thyrotrophs in anterior which then produce TSH which then stimulates thyroid gland to produce T4 and T3
what are the features of the TSH receptor?
it is a GPCR that activates a cAMP pathway to increase production of the T3/T4
how is TSH production regulated?
via negative feedback at TRH neurones in hypothalamus and at thyrotrophs
what are the signs of a thyroid disorder?
moon face, weight gain, fat accumulation of upper back, mood swings, impaired memory
what is the mechanism of a thyroid function test?
the higher the TSH the lower the thyroid function as less T3 or T4 being produced
what type of hypothyroidism is most common?
autoimmune
what is Hashimoto’s?
autoimmune hypothyroidism
what type of treatment may result in hypothyroidism?
end stage radioactive graves treatment
what are the indicators of hypothyroidism?
iodine deficiency, decreased thyroid hormones, slower metabolism, susceptible to cold as less heat generated
what are the symptoms of hypothyroidism?
weakness, fatigue, cold intolerance, decreased sweating, weight gain, impaired glucose tolerance
what is primary hypothyroidism?
issue with the thyroid
what is secondary hypothyroidism?
issue with the pituitary gland causing decreased stimulation of thyroid
what is tertiary hypothyroidism?
hypothalamus no longer functioning preventing the flow of hormones
what kind of hypothyroidism does a high TSH indicate?
primary as indicates that the thyroid is not working to produce hormones for negative feedback
what is the treatment of hypothyroidism?
synthetic thyroxine to replace T4
what makes type I diabetics more likely to suffer with hypothyroidism?
autoimmunity may damage the thyroid
what is Grave’s disease?
hyperthyroidism
what could hyperthyroidism be caused by?
toxic multi nodular goiter, TSH secreting pituitary tumour, molar pregnancy
what are the common symptoms of graves disease?
hyperactivity, insomnia, excessive sweating, weight loss, increased defecation
what are the less common symptoms of hyperthyroidism?
loose nails, impotence, nausea or vomiting
what is a goiter?
swollen thyroid gland
what does an assessment of the goiter include?
size, painfulness, smoothness, is it causing issues to breathing
what things indicate diagnosis of hyperthyroidism?
TSH suppressed due to high T4, toxic multi nodular goiter, check T3 in case of thyrotoxicosis, check response to TSH
what is the treatment of hyperthyroidism? how does it work?
radioactive iodine as this is transported to the thyroid and so will kill the tissue that is producing too much hormone
what patients cannot have radioactive iodine treatment?
children or pregnant women
what are the issues with radioactive iodine?
increases chances of hypothyroidism as cannot now produce enough hormone
what drugs can be used to treat hyperthyroidism?
propylthiouracil and propranolol
what does propylthiouracil do?
blocks thyroid hormone synthesis
what does propranolol do?
blocks hormone effects by inhibiting conversion of T3 to T4
how is thyroiditis caused?
by viral infections
what are the symptoms of thyroiditis?
tender thyroid with fever and malaise
how can thyroiditis be treated?
using beta blockers such as propranolol
what is Hashimoto’s thyroiditis?
inflammation of the thyroid causing hypothyroidism
