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IPA > Exam 5 Thyroid > Flashcards

Exam 5 Thyroid Flashcards

1
Q

what is a goiter

A

enlargement of thyroid gland

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2
Q

hypothyroidism vs hyperthyroidism

A

hypo= inadequate thyroid hormone produciton

hyper= (thyrotoxicosis) over production of thyroid gland (hyperfunction of the gland)

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3
Q

what is thyroditis

A

inflammation and destruction of the thyroid gland

ex: hashimoto

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4
Q

name the cascade of thyroid hormone release

A
  1. hypothalamus sends thyrotropin releasing hormone (TRH) to pituitary
  2. pituitary sends thyroid stimulating hormone (TSH) to the thyroid via circulation
  3. thyroid synthesizes and releases T3, T4 and Calictonin
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5
Q

what acts as the negative feedback control for the thyroid hormones

A

T3 and T4 negative feedback to hypothalamus and pituitary

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6
Q

what molecule is needed to produce thyroid hormones and must come from the diet

A

iodine

Ex: iodized salt

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7
Q

is there more T4 or T3 secreted by thyroid

A

90% is T4

majority (80%) of T3 is created by the breakdown of T4
1/3 of T4 converted to T3

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8
Q

what is the active form of T3/4

A

free T3/4- metabollically active

most is bound in proteins= not biologically available for use
thyroxine binding globuline (TBG (99% bound of T4 and 70% of T3)

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9
Q

what comes on a thyroid panel

A

TSH

total T4

Free T3/4

Free T4 index - FT4I
(calculation that shows how much T4 there is relative to binding globulin)

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10
Q

why order a thyroid panel

A

screen for thyroid disease / function of thyroid

monitor treatment of thyroid disorders

assess treatment of hypothyroidism (levothyroxine therapy)

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11
Q

what is the most important test in evaluating thyroid function

A

TSH: more stable in the blood than T3/4

all newborns get this test to screen for congenital hypothyroidism

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12
Q

if TSH is high what does this mean for T3 and T4

A

T3/4 will be low= hypothyroidism

pituitary recognizes low levels of - very sensitive
small changes in T4 cause large changes in TSH

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13
Q

if TSH is low what does this mean for T3 and T4

A

T3/4 will be high= hyperthyroidism

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14
Q

what is the goal of treating hypothyroidism (levothyroxine treatment)

A

provide adequate amount of exogenous T4 to minimize TSH secretion

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15
Q

name some disorders that would increase TSH

A

HYPOthyroidism (congenital=cretinism and primary)

secondary HYPERthyroidism

pituitary adenoma

hashimoto’s thyroditis (autoimmune)

amiodarone/ dopamine antagonist= drugs

ectopic TSH producing tumors

TSH producing pituitary adenoma

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16
Q

name some disorders that would decrease TSH

A

primary HYPERthyroidism

secondary HYPOthyroidism
- TSH near zero!!

Tertiary HYPO thyroidism

graves disease (autoimmune)- has no effect on TSH levels

glucocorticoids= drugs

excessive exogenous thyroid hormone

high levels of chronic gonadotropin

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17
Q

what is primary hypothyroidism?

Secondary?

Tertiary?

A

primary: problem with thyroid
secondary: problem with pituitary
tertiary: problem with hypothalamus

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18
Q

what is primary hyperthyroidism?

secondary?

A

primary: problem with thyroid
secondary: problem with pituitary

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19
Q

in which disorder would TSH levels be near zero!!!

A

secondary hypothyroidism

20
Q

what test is a direct measure of ALL circulating T4 (thyroxine)

A

total T4

this is protein bound and free

21
Q

what are the critical values for Total T4

A

low: myxedema coma (under 2mcg/dl) due to hypothyroid, protein deficiency
- causes everything to slow down (hypotension, bradycardia, lethargy, etc)

high: thyroid storm (over 20 mvg/dl)
due to: hyperthyroid, too much iodine, high levothyroxine med, hepatitis
- causes hyper everything speeds it up
-hyperthermia, dehydration, shock

22
Q

what test is not affected by fluctuations in TBG (thyroid binding globulin)

A

free T3/4

  • aka good for evaluating ppl with protein abnormalities
23
Q

what test is most accurate indicator of T4 activity

A

free T4

used if not enough info from TSH

24
Q

when should you check free T3 and T4

A

when suspect HYPER thyrodiism

need to rule out T3 toxicosis

25
Q

what are thyroid immunoglobulins

what are the types

A

IgG antibodies directed against thyroid receptor antigens

3 types
1. thyroid peroxidase (TPOAb or Anti-TBO= anti thyroid peroxidase antibody)

  1. thyroglobulin (TgAb or Anti-Tg= anti thyroglobulin antibody)
  2. TSH receptor Antibody (TRAb= anti TSH receptor antibody)
    - TSI
    - TBII
26
Q

what would cause elevated TPOAb, TgAB

A

In order of most prevalence:

hashimoto disease

also graves, but most likely hashimoto

other autoimmune diseases (type 1 diabetes)

pregnancy

goiter, isolated thyroid nodule, cancer

27
Q

when should you order a TPOAb

A

to confirm Hasimotos (though you dont have to treat)

or when pt with subclinical hypothyroidism to determine Tx plan (aka present with hypo but labs in normal range)

28
Q

what thyroid test helps confirm graves

A

anti TSH receptor antibody (TRAb)

checks for anti TSH receptor antibodies that would cause the continous firing of the receptor

Two types TSI and TBII

29
Q

what do nuclear thyroid scans do

A

measure thyroid funciton

evaluate thyroid nodules

find causes of hyperthyroidism / plan treatment for hyper/nodule

see spread of thyroid cancer

30
Q

when should you order a thyroid ultrasound

A

initial evaluation of a thyroid nodule!!!!!!!!!!!

31
Q

what is radioactive iodine uptake and scan used for

A

determine if cancerous or not and if spread
give the radioactive iodine and generally hypo = too little taken up and hyper= too much

IN NODULES:
HOT: high uptake- BENIGN
COLD- low uptake CANCER-> nonfunctioning tissue

32
Q

what can congenital hypothyroidism cause

A

irreversible damage to CNS

developmental defects

33
Q

symptoms of HYPO thyroid

A

fatigue

cold intolerance

dry skin

constipation

weight gain

depression

bradycardia

menorrhagia

34
Q

symptoms of HYPER thyrodisim

A

anxiety

weakness

tremor

palpitation

heat intolerance

weight loss

exophthalmia

goiter

35
Q

what do you do if you get a high TSH

A

first repeat TSH and check free T3/4 and index

if normal= original = error

if TSH still high= and free T4 low then hypothyroid

if TSH high but free T4 normal= subclinical hypothyrodism

same for low TSH but opp TSH low, high T4/T3= hyper

36
Q

is HYPER or HYPO thyroidism more common

A

hypo = 95% of cases

37
Q

what test would you order for pt with goiter

A

ultrasound + thyroid panel

38
Q

if a pts TSH is low and Free T3/4 high what does this indicate

A

hyperthyroidism

39
Q

what else could you order for a pt with hyperthyroidism and a goiter after the ultrasound

A

radioactive iodine uptake to determine if cancerous and then a biopsy

cold means cancer = low uptake

refer

40
Q

what would you order for a pt complaining of flu like symptoms and an enlarged thyroid

A

thyroid panel

41
Q

how long does it take for TSH levels to respond to levothyroxine treatment

A

4-6 weeks!!!!

42
Q

what does high levels of thyroid peroxidase antibodies indicate (TPOAb)

A

hashimoto thyroiditis = elevated TPOAb

43
Q

what is the first and primary test done to check thyroid

A

TSH

most sensitive and specific screening lab

44
Q

what condition would you exepct in person with HIGH TSH

low TSH

A

high TSH= hypo

low TSH= hyper

45
Q

pt with thyroid nodule should have what initial study

A

ultrasound and thyroid panel

IPA (14 decks)

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