Thyroid disorders

Question 1

Thyroid is derived from what? Parathyroid?

Answer 1

(4th and 5th pharygeal pouches)

PT = 3rd and 4th

Question 2

What week does the ability to concentrate iodine occur?

Answer 2

12 weeks

Question 3

What week does HPT axis funcitonal

Answer 3

18 weeks:

Question 4

“Total T4/T3” = free or bound

Answer 4

bound

Question 5

What is the active form of thyroid called

Answer 5

Free (FT3/FT4)

Question 6

If unspecified, it is referring to which form of thyroid homo

Answer 6

the bound, “Total” form

Question 7

4 Bs of thyroid function

Answer 7

i. Brain maturation
ii. Bone maturation
iii. β-adrenergic effects (myocardial contractility)
Basal Mtb rate increase - thermogenesis

Question 8

thyroid relationship with catecholamines

Answer 8

increases sensitivity to catecholamines

Question 9

Which thyroid homo is essential for growth and dev

Answer 9

T4

Question 10

When is the normal surge in T4

Answer 10

~day after birth

Question 11

MC cause of congenital hypothyroidism

Answer 11

Thyroid agenesis/dysgenesis

Question 12

2nd MC cause of congenital hypothyroidism

Answer 12

Dyshormonogenesis = organification enzyme defect

Question 13

If normal Tc99 scan in congenital hypothyroidism, what is cause

Answer 13

Dyshormonogenesis

Question 14

Labs (TSH, T3/T4) : primary and central/secondary/pituitary hypothryroidism

Answer 14

Primary = high TSH ( normal pituitary), low T4/T3
central/secondary/pituitary= low/inappropriately normal TSH, low T3/T4

Question 15

2 medication causes of acquired hypothyroidism

Answer 15

Amiodarone, lithium

Question 16

define myxedema

Answer 16

Hypothyroidism in older kids and adults

Question 17

Sx of myxedema

Answer 17

goiter

Fatigue, constipation, cold intolerance, dry skin, brittle hair, puberty delay

Question 18

What is the MC cause of enlarged Thyroid?

Answer 18

hashimotos thyroiditis

Question 19

2 mechanisms of hashimotos

Answer 19

CD4, CD8, and antithyroid antibodies

→ destruction of thyroid

Question 20

2 Dx lab findings for hashimotos

Answer 20

Anti-Thyroid Peroxidase Ab (Anti-TPO)

Anti-Thyroglobulin Ab (Anti-TG).

Question 21

tx for hashimotos

Answer 21

levothyroxine

Question 22

T4 = what drug?

Answer 22

levothyroxine

Question 23

T3 = what drg

Answer 23

triiodothyronine

Question 24

Which has longer half life? T3 or T4

Answer 24

T4

Question 25

Administration instructions for levothyroxine and why

Answer 25

Take on empty stomach | Food, PPIs, antacids all decrease absorption

Question 26

What is T3 ix for

Answer 26

Indicated for acute emergencies only

Question 27

ADE of T3

Answer 27

adverse cardiac effects

Question 28

what drug increases both T4 and T3 ?

Answer 28

levothyroxine

Question 29

Diagnosis and Cause of Graves dz:

Answer 29

Thyroid Receptor Stimulating Antibodies (TRS-Ab) aka TSI

Question 30

pretibial myxedema cuased by

Answer 30

GAG deposition

Question 31

What antibodies are found in graves?

Answer 31

1. Anti-Thyroid Peroxidase Ab (present in hashimotos too) 2. Anti-Thyroglobulin Ab (present in hashimotos too) 3. TSI

Question 32

RAI findings in Graves

Answer 32

Diffuse uptake on radioactive iodine scan.

Question 33

Tx for Graves (3)

Answer 33

Methimazole, B-blockers, radioactive ablation

Question 34

Methimazole MOA

Answer 34

inhibits peroxidase

Question 35

SX of neonatal graves (6)

Answer 35

Tachy, cardiomegaly/CHF, SGA/preemie, microcephaly, stare, hepatosplenomegaly

Question 36

Carbimazole MOA

Answer 36

blocks peroxidase

Question 37

PTU MOA

Answer 37

blocks thyroid-peroxidase and 5'-deiodinase (conversion of T4--> T3)

Question 38

What biochemical structure is essential for Methamizole and PTU to work

Answer 38

Thiocarbamide groups

Question 39

Why isn't Carbimazole used much?

Answer 39

Carbimazole is converted to Methimazole quickly so it isn't used very much

Question 40

Which Thyroid drug crosses the pacenta less?

Answer 40

PTU

Question 41

How soon will thryoid drugs show effects and why?

Answer 41

1) Blocks synthesis but not release: a) Stored TG not affected Effects take weeks (until stores are depleted)

Question 42

Most dangerous ADE of thiamides

Answer 42

Agranulocytosis (BM suppression) = most dangerous

Question 43

Methimazole ADE:

Answer 43

Aplasia cutis congenital = lack of scalp skin

Question 44

all thiamides show this ADE and which one especially?

Answer 44

PTU especially shows hepatotoxicity

Question 45

PTU is Cix in what situations?

Answer 45

1. kids unless no other option available | after 1st trimester of pregnancy

Question 46

Unique use of Iodine salts

Answer 46

Blocks RAI (radioactive iodine) uptake in event of nuclear reactor accident, etc

Question 47

RAI is absolutely cix in what pop?

Answer 47

absolutely cix in pregnancy and nursing mothers.

Question 48

B-blocker MOA on thyroid homo

Answer 48

Decreases conversion of T4-->T3.

Question 49

etiology of Subacute Thyroiditis (de Quervain Thyroiditis)

Answer 49

Viral etiology: | Measles, mumps, adenovirus, coxsackie

Question 50

CP and course of Subacute Thyroiditis (de Quervain Thyroiditis)

Answer 50

Tender thyroid - only disorder with tender thyroid! | Self-limiting

Question 51

Sick Euthyroid lab and why?

Answer 51

``` ↑↑rT3 (reverse T3) = inert form of T3 decreased T3 (bc T4 is converted in to rT3 instead of T3) ```

Question 52

What does the Swallow testtell you?

Answer 52

if it move up and down = thyroid related

Question 53

FNA is recommended for all thyroid nodules that show what (2)?

Answer 53

> 1cm | solid, mixed components

Question 54

Most thyroid adenomas functioning or not?

Answer 54

non = "cold"

Question 55

Which thyroid nodule is more likely to become malignant: hot or cold?

Answer 55

cold

Question 56

MC and 2nd MC thyroid CA

Answer 56

1. = Papillary | 2. Follicular

Question 57

How to dx follicular CA

Answer 57

invasion through capsule (if not = adenoma)

Question 58

What thyroid CA is seen in Seen in iodine deficient regions

Answer 58

Follicular

Question 59

Inheritance of Medullary CA

Answer 59

AD

Question 60

MEN2A has what conditions

Answer 60

2A: Medullary CA, parathyroid hyperplasia, Pheochromocytoma

Question 61

MEN2B has what conditions

Answer 61

2B: Medullary CA, Pheochromocytoma, mucosal neuromas, marfanoid body habitus

Question 62

Anaplastic CA of thyroid | population, px, mutation

Answer 62

older pop 100% lethal p53

Question 63

Thyrotropin alpha: MOA and use

Answer 63

= synthetic TSH | Give before RAI ablation in thyroid cancer to beef up the thyriod