B8-058 Hypothyroidism

Question 1

in primary hypothyroidism, TH will be […] and TSH will be […]

Answer 1

in hypothyroidism, TH will be [low] and TSH will be [high]

Question 2

anti-TPO or anti-thyroid globulin antibodies would indicate

Answer 2

Hashimotos

Question 3

why do you give T4 over T3?

Answer 3

longer half life

Question 4

treatment for hypothyroidsm

Answer 4

levothyroxine

Question 5

how does hypothyroidism increase prolactin?

Answer 5

low T3/4 —> increased TRH/TSH –> increased prolactin

Question 6

[…] play a role in regulating TBG levels

Answer 6

estrogens

(low estrogen –> low TBG –> low SHBG)

Question 7

prolactin inhibits […] causing amenorrhea

Answer 7

GnRH

Question 8

how does hypothyroidism impact the menstrual cycle leading to amenorrhea?

Answer 8

low T3/T3 stimulates TRH release
TRH stimulates prolactin release
Prolactin stimulates CRH release
CRH inhibits GnRH release

–> decreased FSH —> decreased estrogen

Question 9

how does hypothyroidism cause galactorrhea?

Answer 9

low T4 and T3 lead to increased TRH and prolactin

increased prolactin causes excess milk production

Question 10

normal T4 despite low TSH

(outside of pregnancy)

Answer 10

subclinical hypothyroidism

(antibodies “masking” TSH receptors)

Question 11

in the first trimester, […] can bind TSHR to stimulate the thyroid gland

Answer 11

hCG

(may need to stop levothyroxine if taking)

Question 12

what maintains elevated thyroid hormone levels in the 2nd and 3rd trimesters?

Answer 12

high levels of TBG (from high estrogen) slows degradation of hormones

Question 13

thyroid receptor antibodies can be both […] and […]

Answer 13

inhibitory
stimulatory

(subtypes coexist but dominant subtype will determine physiologic response)

Question 14

normal T4 despite low TSH in pregnancy could be caused by

Answer 14

mother with hypothyroidism, but hCG and TBG are compensating

Question 15

high levels of estrogen secreted by the placenta in pregnancy stimulate hepatic production of

Answer 15

TBG, SHBG

Question 16

increased TBG will lead to an [increase/decrease] in circulating hormone levels

Answer 16

increase

Question 17

high levels of […] can induce prolactin to downregulate GnRH secretion and ovarian function

Answer 17

TRH

Question 18

secondary hyperthyroidism is caused by

Answer 18

excessive secretion of TSH from thyrotropes

Question 19

primary hyperthyroidism is caused by

Answer 19

excessive secretion of thyroid hormone

TSH independent

Question 20

TSH would be […] in primary hyperthyroidism

Answer 20

decreased

Question 21

TSH would be […] in secondary hyperthyroidism

Answer 21

increased

Question 22

eyelid lag/retraction
periorbital puffiness
exophthalmos

are characteristic of

Answer 22

Grave’s

Question 23

Grave’s disease is […]thyroidism

Answer 23

hyper

Question 24

Hashimotos’s disease is […]thyroidism

Answer 24

hypo

Question 25

describe expected TBG, total T4 and free T3 levels in a normal pregnancy

Answer 25

increased TBG
increased total T4
normal free T4

Question 26

increased hCG causes a decrease in […] during the first trimester

Answer 26

TSH

hCG can bind TSH receptors and stimulate TH production

Question 27

free T3/T4 levels [increase/decrease] in the second and third trimesters

Answer 27

decrease

i think decrease back to normal as hCG lowers and estrogen stabilizes?

Question 28

increased TBG during the first trimester causes [increased/decreased] total T3/4

Answer 28

increased

Free T3/4 remains the same or just slightly elevated

Question 29

estrogen stimulation of the liver increases the production of […] in pregnancy [3]

Answer 29

TBG
SHBG
albumin

Question 30

primary hypothyroidism is caused by

Answer 30

insufficient thyroid hormone production

(TSH will be high)

Question 31

secondary hypothyroidism is caused by

Answer 31

pituitary disorders (adenoma)

TSH will be low

Question 32

TSH will be […] in primary hypothyroidism

Answer 32

high

Question 33

TSH will be […] in secondary hypothyroidism

Answer 33

low