HRR Week 2

Question 1

MOA for methimazole (Tapazole):

Answer 1

• Inhibits oxidative binding of iodide to thyroglobulin

- Inhibits coupling of iodide to tyrosine

Question 2

Contraindications/cautions for methimazole (Tapazole):

Answer 2

Pregnancy, breastfeeding, hepatic impairment, agranulocytosis, myelosuppression

Question 3

Serious side effects of levothyroxine (Synthroid):

Answer 3

CHF, arrythmias, HTN, angina

Question 4

Common side effects of levothyroxine (Synthroid):

Answer 4

SSx of hyperthyroidism

Question 5

MOA for propylthiouracil (PTU):

Answer 5

• Inhibits oxidative binding of iodide to thyroglobulin
• Inhibits coupling of iodide to tyrosine
• Inhibits peripheral conversion of T4 to T3

Question 6

Contraindications/cautions for propylthiouracil (PTU):

Answer 6

Hepatic impairment, myelosuppression, peds

Question 7

Indications for propylthiouracil (PTU):

Answer 7

Reserved for hyperthyroid patients who can’t take methimazole and who aren’t candidates for surgery or radioactive iodine tx

Question 8

Contraindictions/cautions for liotrix (Thyrolar):

Answer 8

MI, adrenal insufficiency

Question 9

Contraindications for levothyroxine (Synthroid):

Answer 9

Contraindications: MI, adrenal insufficiency, thyrotoxicosis, pre-existing TSH suppression.

Cautions: CV disease, elderly, DM

Question 10

AEs for liotrix (Thyrolar):

Answer 10

Serious: arrythmias
Common: same as levothyroxine

Question 11

Side effects for methimazole (Tapazole):

Answer 11

Most common: rash
Others: leukopenia, hypersensitivity, GI upset, transient elevated LFTs
Rare: Jaundice/hepatitis, agranulocytosis

Question 12

Interactions with levothyroxine (Synthroid):

Answer 12

Beta blockers, bile acid sequestrants, carbamazepine and phenytoin, orlistat, OCPs, digoxine, theophylline, warfarin, amiodarone, phenobarbitol, rifampin, PPIs, sulcralfate

Question 13

Patient education for levothyroxine (Synthroid):

Answer 13

• Take on empty stomach 30 - 60 min before breakfast, or at bedtime if it’s been 3 hours since last meal
• Don’t switch from brand to generic, or retest TSH in 6 weeks if you do

Question 14

Patient education for methimazole (Tapazole):

Answer 14

May cause fetal harm if pregnant

Question 15

Patient education for propylthiouracil (PTU):

Answer 15

May cause liver failure

Question 16

T3 resin uptake:

Answer 16

• Old fashioned way of measuring free T3/T4 (not used anymore since free T3/T4 and TBG tests are available)
• Measures amount of TBG in the blood, which affects levels of free TT3/4
• Can help distinguish between true hyper/hypothyroidism and apparent hyper/hypothyroidism due to abnormal TBG

Question 17

Causes of hypothyroidism:

Answer 17

• Hashimoto’s thyroiditis (most common)
• Iatrogenic (surgery, radiation)
• Drugs (amiodarone, lithium, iodine def.)
• Subacute/Postpartum thyroiditis
• Congenital
• 2-ary/central hypothyroidism (pituitary def.)

Question 18

Definition of subclinical hypothyroidism:

Answer 18

Mildly elevated TSH, normal free T4

Question 19

Guidelines for biopsy of thyroid nodules:

Answer 19

> 1 cm with high/intermediate suspicion
1.5 cm with low suspicion
2 cm with very low suspicion

Question 20

What imaging technique should be used to evaluate suspected thyroid nodules?

Answer 20

Ultrasound

Question 21

How is an I-123/I-131 scan used to evaluate thyroid nodules

Answer 21

• Done when TSH is suppressed
• In theory, “hot” nodules almost never cancerous
• Cold nodules should be biopsied (still, most cold nodules are benign)

Question 22

Common etiologies of female and male hypergonadotropic hypogonadism:

Answer 22

• Female: Turner’s syndrome

- Male: Klinefelter syndrome

Question 23

Name the gonadotropins:

Answer 23

• LH (leutenizing hormone)

- FSH (follicle stimulating hormone)

Question 24

Describe the pathophysiology of hypergonadotropic vs hypogonadotropic hypogonadism:

Answer 24

• Hypergonadotropic: Source of the problem is at the gonads (ovaries or testes).
• Hypogonadotropic: Source of the problem is in pituitary or hypothalamus
• Gonadotropins (LH and FSH) are high, as well as GNRH since both of these systems are functional.