Hypothalamic Pituitary And Thyroid Hormone

Question 1

Somatostatin analogs

Answer 1

Inhibit release of GH, glucagon, insulin, and gastrin

Octreotide

Question 2

D2 receptor Agonist

Answer 2

Bromocriptine and Cabergoline

Inhibits prolactin release but some efficacy against small GH secreting tumors at high doses

Question 3

Thyroid hormone transport

Answer 3

Mostly protein bound by thyroxine-binding globulin or albumin
Small amount is free, free = active
Thyroid hormone pool has stable 7 day half life

Question 4

Levothyroxine

Answer 4

Synthetic T4

AE: nervousness, heat tolerance, palpitation/tachycardia, wt loss

Question 5

Radioactive iodine

Answer 5

131 I
Rapidly absorbed, concentrated in thyroid, and incorporated into storage follicles
Crosses placenta and excreted in breast milk (CI)

Question 6

Thioamides

Answer 6

Methimazole: lower risk of liver damage
Propylthiouracil (PTU): inhibits conversion of T4 to T3 and brings levels down faster
Inhibit thyroid peroxidase-catalyzed rxns and block iodine organification (prevents binding of iodide to tyrosine)
AE: severe hepatitis (PTU) and agranulocytosis

Question 7

Iodides

Answer 7

Potassium iodide
Block release of T4 and T3 and inhibit iodine organification
Reduce size of hyperplastic gland (preoperative prep for surgery)
Wolff-Chaikoff effect
Cross placenta and can cause a fetal goiter

Question 8

Beta blockers

Answer 8

Propranolol

Inhibits peripheral conversion of T4 to T3

Question 9

Glucocorticoids

Answer 9

Dexamethasone and hydrocortisone

Inhibit peripheral conversion of T4 to T3

Question 10

Aspirin and NSAIDs

Answer 10

Decrease protein binding -> inc free thyroid hormone -> inc activity

Question 11

Amiodarone

Answer 11

Inhibits conversion of T4 to T3

Contains 2 iodine atoms