thyroid

Question 1

only _____ thyroid hormone has biological effects

Answer 1

unbound

Question 2

t4 source vs t3 source

Answer 2

T4 only source is thyroid gland
T3 <20% comes from thyroid gland. most is produced by breakdown of T4 by deiodinase enzyme

Question 3

binding affinity T3 vs T4

Answer 3

T3 has a 10-15x higher binding affinity than T4

Question 4

t/f: all thyrotoxicosis is hyperthyroidism

Answer 4

false

Question 5

the symptoms of thyrotoxicosis can be described as

Answer 5

speeding up and heating up
ex hyperactive, sweating, palpitations, weight loss w/ inc appetite, diarrhea, etc

Question 6

diagnostics of thyrotoxicosis

Answer 6

decreased TSH (due to negative feedback)
increased T3, T4
RAIU
TSAbs if grave’s disease

Question 7

what are the most common causes of thyrotoxicosis with increased RAIU

Answer 7

Grave’s disease
toxic adenoma
multinodular goiter

Question 8

which is the most common cause of hyperthyroidism

Answer 8

Grave’s

Question 9

describe actions of grave’s?

Answer 9

autoimmune: actions of thyroid-stimulating antibodies (TSAbs) against thyrotropin receptor
thyroid enlarged 2-3x normal
disproportionate increase in T3 relative to T4

Question 10

description of toxic adenoma?

Answer 10

“hot nodule”
autonomous thyroid nodule, benign tumor producing thyroid hormone

Question 11

description of multinodular goiter?

Answer 11

autonomous follicles

Question 12

most common causes of thyrotoxicosis with suppressed RAIU

Answer 12

subacute thyroiditis
painless thyroiditis
exogenous thyroid hormone
meds containing iodine

Question 13

describe subacute thyroiditis/treatment?

Answer 13

systemic symptoms like flu: fever, malaise, myalgia
self limiting: ANTITHYROID DRUGS ARE NOT INDICATED
treatment is symptom management: beta blockers, NSAIDS, prednisone

Question 14

describe painless thyroiditis/treatment?

Answer 14

painless/silent– can happen postpartum. self-limiting: antithyroid drugs are not indicated. give propranolol or metoprolol

Question 15

what can cause ingestion of exogenous thyroid hormone

Answer 15

overtreatment, pharmacy errors, accidental– ground beef contaminated

Question 16

what medications contain iodine that can induce thyrotoxicosis

Answer 16

amiodarone

Question 17

withhold ____ for 24-48 hours prior to laboratory testing

Answer 17

biotin

Question 18

antithyroid medications

Answer 18

methimazole first line
propylthiouracil

Question 19

when to consider surgery for thyrotoxicosis

Answer 19

large thyroid gland >80g
severe ophthalmopathy
lack of remission

Question 20

when is radioactive iodine the choice therapy for thyrotoxicosis

Answer 20

toxic nodules & multinodular goiter

Question 21

disadvantages for radioactive iodine

Answer 21

permanent hypothyroidism
worsening ophthalmopathy: avoid in eye disease
contraindicated in pregnancy and breastfeeding, defer pregnancy x 6 months

Question 22

what is the limitation to methimazole

Answer 22

possible teratogen, avoid 1st trimester pregnancy

Question 23

surgery downside for thyrotoxicosis

Answer 23

leads to permanent hypothyroidism

Question 24

what are the limitations for propylthiouracil

Answer 24

hepatotoxicity
limited to: 1st trimester pregnancy, thyroid storm, patients with adverse effects to methimazole

Question 25

thyroid storm

Answer 25

life threatening medical emergency

Question 26

primary hypothyroidism: causes

Answer 26

hashimoto's, iatrogenic

Question 27

what is central hypothyroidism

Answer 27

dysfunction of pituitary or hypothalamus

Question 28

what is hashimoto's

Answer 28

autoimmune; antithyroid peroxidase antibodies, presents as goiter/ hypothyroidism

Question 29

what causes iatrogenic hypothyroidism

Answer 29

destructive amounts of radiation, surgery

Question 30

pituitary disease of central hypothyroidism culprit is __

Answer 30

TSH

Question 31

hypothalamic disease of central hypothyroidism culprit is ___

Answer 31

TRH deficiency

Question 32

hypothyroidism presentation can be described as

Answer 32

slowing and cooling children: delays growth, development dry skin, cold intolerance, weight gain, constipation, weakness

Question 33

diagnosis of hypothyroidism

Answer 33

increased TSH for primary inappropriately normal TSH for secondary autoantibodies in hashimoto's

Question 33

treatment of hypothyroidism

Answer 33

levothyroxine

Question 34

liothyroxine

Answer 34

higher incidence of cardiac adverse events

Question 34

desiccated thyroid

Answer 34

antigenic in allergic/sensitive patients

Question 35

levothyroxine at excessive doses can cause

Answer 35

heart failure, angina, MI, decreased bone density

Question 36

starting dose for levothyroxine

Answer 36

25 mcg for elderly with known cardiac disease 50 mcg for most

Question 37

titrating levothyroxine

Answer 37

25 mcg increments monthly average maintenance dose is 125 mcg

Question 38

levothyroxine with food

Answer 38

food impairs absorption

Question 39

TSH normal range

Answer 39

0.5 to 4.5

Question 40

levothyroxine drug interactions

Answer 40

H2RAs, PPIs, rifampin, carbamazepine, phenytoin

Question 41

myxedema coma

Answer 41

decompensated hypothyroidism: need IV levothyroxine and IV hydrocortisone

Question 42

pregnancy with hypothyroidism

Answer 42

increase levothyroxine dose 20-30%: 2 additional tablets a week