Tyroid path and pharm

Question 1

What effect would giving T3 suppliment have on TSH, T3, reverse T3 and T4 in a patient with hypothyroidism?

Answer 1

TSH would go down, T3 would increase, and both T4 and reverse T3 would decrease

reverse T3 is an inactive product of peripheral deodination of T4 and thus not influenced by supplimental T3

TSH would decrease due to feedback (decreased TRH and TSH release)

Question 2

what should be given prophylactically in the event of a nuclear accident or suspected exposure to radioactive iodine-131?

Answer 2

potassium iodide to prevent radiation induced hypothyroidism

2 mechanisms:

potassium iodide dissociates and iodide competitively inhibits uptake of iodine-131 at the sodium iodide sypototer on the basolateral membrane of thyroid follicular cells

large increases in serum iodine also inhibit organification and reduce tyroid hormone secreations

Question 3

what is levoxythryine? How does it affect iodine uptake?

Answer 3

synthetic T4 used for hypothyroidism - high toses suppress TSH similar to T4, which suppresses iodine uptake (trapping) into follicular cells

TSH promotes iodine trapping

Question 4

what is the MAO of propothiouricil?

Answer 4

inhibits thyroid peroxidase - used for treatment of hyperthyroidism

inhibits organification and coupling of iodotyrosines (DIT MIT)

ALSO inhibits peripheral conversion of T4 to T3

Question 5

what is the MAO of methimazole?

Answer 5

inhibits thyroid peroxidase (inhibits iodine organification and coupling of iodotyrosines)

NO effect on peripheral conversion of T4 to T3 (unlike propothiouricil, which also inhibits this)

Question 6

what is the mechanisms for perchlorate or pertechnetate?

Answer 6

inhibits sodium-iodide symporter

Question 7

when can beta blockers be used for thryroid disorders?

what is the MAO?

Answer 7

for hyperthryroidism
decreeases effects of thyroid hormones on target tissues

propranolol also decreases the peripheral conversion of T4 to T3