Thyroid Function in Health and Disease Flashcards
What hormones does the thyroid gland produce?
T3, T4 and calcitonin
Which part of the thyroid produces calcitonin?
C cells
Describe the process of thyroid hormone synthesis
the follicular cell synthesises thyroglobulin and enzymes, a sodium iodide symporter brings iodide in to the follicle cell from the blood, a pendrin transporter brings iodide into the colloid, iodine is added to tyrosine on thyroglobulin, thyroglobulin with the iodine is taken back into the follicular cells, enzymes separate the T3 and T4 from the thyroglobulin and allow them to enter the circulation
What is the action of TSH?
stimulates all of the steps in thyroid hormone synthesis
What factor in infants will increase the expression of TRH?
cold
What will decrease the expression of TRH?
stress
What is the chemical structure of thyroid hormones?
iodinated amine
What is the half life of T4 and T3?
6-7 days for T4 and 1 day for T3
What is the cause of low T3, low T4 and high TSH?
thyroid failure or a lack of dietary iodine
Does secondary hypothyroidism cause a goitre?
no
What are the symptoms of hypothyroidism?
decreased energy, increased weight, cold intolerance, increased heart rate, decreased mentation and reflexes, fatigue, myxedema
Does secondary hyperthyroidism cause a goitre?
yes
What are the symptoms of hyperthyroidism?
increased appetite, weight loss, muscle weakness, heat intolerance, increased heart rate, increased alertness, irritability, hyperexcitability
What causes the exopthalmos in Grave’s disease?
water retaining carbohydrates behind the eyes
