1. thyroid Flashcards
what does parathyroid hormone do and when is it released
control Ca metabolism
released by LOW plasma Ca
what do follicular cells of the thyroid make
T3 aadn T4
what do parafollicular cells make
calcitonin for Ca metabolism
released by HIGH plasma Ca
why is the thyroid important in develpemt
aid neural tube development in the fetus
describe the control of synthesis
- hypothalamus releases TRH
- stimulates TSH
- which stimulates thyroid gland to release TH (mainly T4)
how are the levels of TH controlled
T4 is converted to T3 in the periphery (more potent on receptors)
T3 acts on thyrotrophs to reduce TSH release
what are the TH binding proteins (for T3 and T4)
- T3 and T4 bind with TBG (thyroid binding globulin)
- T3 binds to albumin
- T4 binds to TBPA (thyroxine binding pre-albumin) or transthyretin
what are 2 main conditions associated with hypothyroidism
hashimotos thyroiditis
myxoedema
what are the treatment options for hashimotos
- radiotherapy
- surgery
- thyroxine T4 (low dose daily) - effect lasts 14days
- liothyronine (sodium salt of T4) - effect lasts 8 days
treatment for myxoedema
- iodine supplements
- gotrogen (suppress hormone secretion and increase TSH secretion)
what are the normal values for dietary iodine requirement, and iodine deficiency
dietry requirement = 150ug/day
deficiency < 50ug/day
what is graves disease/thyrotoxicosis
hyperthyroidism
what are clinical features for graves disease
- thyrotoxicosis
- exophthalmos
- pretibial myoedema
treatment for graves
- antithyroid drugs
- B-blockers - propanol
- radioiodide
- surgery: partial thyroidectomy
- iodine in LUGOL’s solution (5%I and 10% KI)
what are some antithyroid drugs used for graves, duration and side effects
- carbimazole (converted to methimazole in the body(
- propylthiouracil (prevent T4–>T3)
treat for 12-18 months
side effects: neutropenia, angranulocytosis (leukopenia aka low WBC), sore throat
