Pharm 2 Thyroid Flashcards Preview

Test 9 > Pharm 2 Thyroid > Flashcards

Flashcards in Pharm 2 Thyroid Deck (21):
1

Thyroid feedback

1. T3/4 reduce TRH receptor number
2. T3/4 inhibit hypothalamus -> TRH

2

Thyrotropin (TSH) subunits

a - identical to LH, FSH, CG
b - confers specificity

3

TSH inhibited by

SRIF
B agonists
Stress (glucocorticoids)

4

TSH deficiency

rare - usually due to tertiary hypothyroidism

5

Iodide uptake

"Iodide trapping"
-Active transport creates 20:1 iodide ratio

6

TSH regulation of T3/4 production

++ Every fucking step

7

Wolff-Chaikoff effect

Extreme iodide excess suppresses thyroid by inhibiting peroxide formation, decreases iodide trapping

8

T3;4 t1/2

T3 - 1 day
T4 - 5-7 days

9

T3 binding site

Nuclear hormone receptor

10

Normal thyroid function

-Increase blood glucose
-Increase Na/K ATPase activity
-Increase heart rate and contractility

11

-Levothyroxine-

Synthetic T4
-1st line for routine replacement
-long half life

12

-Liothyronine-

Synthetic T3
-Rapid, used for emergencies

13

Different levothyroxine doses

-More for children and pregnant
-Loading dose for neonates
-Less for elderly and cardiac disease

14

IV levothyroxine or liothyronine

Myxedema coma (hypothyroidism + illness)

15

Drugs that induce CYP450 and increase T4 clearance

Phenytoin, Carbamazepine

16

-Levothyroxine-
contraindications (4)

-Adrenal insufficiency (increases cortisol turnover)
-Diabetes (hyperglycemia)
-Cardiovascular disease
-Coumarin anticoagulants (increases clotting factor catabolism)

17

Thionamides

Anti-thyroid agents (inhibit thyroid peroxidase)
-Methimazole (6 hour half life)
-Propylthiouracil (1.5 hour half life)

18

Thionamide indications

-Graves
-Deplete T before surgery
-Deplete T before/after radioiodine Tx

19

Thionamide AE

-Reversible agranulocytosis
-Hepatic abnormalities
-necrosis (propylthiouracil)
-cholestatic jaundice (methimazole)

20

Radioactive Iodine (131)

-8 day t1/2
-safe because of iodide trapping

21

Thyrotoxic crisis Tx

-B or Ca blockers for symptoms
-Thionamide
-IV iodide (wolff-chaikoff effect)