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Thrall > Thyroid, Adrenal, and Pituitary > Flashcards

Thyroid, Adrenal, and Pituitary Flashcards

1
Q

In euthyroid sick (decide if increased or decreased):
TT4-
fT4-
rT3-

A

TT4- decreased
fT4- decreased
rT3- increased

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2
Q

Why is TT3 not very good for diagnosing thyroid diseases?

A

mostly comes from outside the thyroid

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3
Q

T or F: T4 is extremely high in birds and reptiles.

A

F- it’s extremely low b/c not as many binding proteins

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4
Q

What is a scenario where a dog w/normal TT4 could really have hypothyroidism?

A

10% have anti-T4 antibodies that can cause T4 to increase and mask hypothyroidism

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5
Q 
Indicate a decrease, increase or N-
For primary hypothyroidism:
TT4-
fT4-
TSH-
A

TT4- decreased
fT4- decreased
TSH- increased

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6
Q

What breeds have lower T4 and fT4?

A

sighthounds and basenjis

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7
Q

What is the interp:
TSH- increased
TT4- decreased
fT4- decreased

A

100% specificity for hypothyroidism

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8
Q

Interpret:
TSH- N
TT4- decreased
fT4- decreased

A

might still be hypothyroid but is in the category of that 25%-33% of dogs with hypothyroidism and no increase in TSH

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9
Q

Interpret:
TSH- decreased
TT4- decreased
fT4- decreased

A

secondary hypothyroidism (only 5% of cases)

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10
Q

What does thyroxine do to TSH?

A

decreases it (can use to monitor hypothyroid treatment)

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11
Q

Interpret TRH response test results:
pre-TRH: TT4 in RI
post-TRH: double the baseline

A

Normal cat (not hyperthyroid)

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12
Q

When would you consider doing a TRH response test?

A

used instead of TSH to ID hypothyroid in dogs or hyperthyroidism in cats when other tests aren’t clear and can’t wait weeks to retest

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13
Q

Interpret the TSH response test results:
pre TSH TT4: below RI
post TSH TT4: increased 2x or more from baseline

A

Euthyroid sick

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14
Q

Interpret the TSH response test:
TT4 pre-TSH: below RI
TT4 post-TSH: below RI

A

hypothyroid

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15
Q

T or F: The presence of antibodies against TT4, TT3 or Tg confirm hypothyroidism.

A

False- just means there is lymphocytic thyroiditis and it may not ever develop into true hypothyroidism.

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16
Q

What is the purpose of running a TSH?

A

to differentiate between primary hypothyroidism, secondary hypothyroidism, and euthyroid sick.

17
Q

In a dog with suspected hypothyroidism that has normal or high T4, what should be considered?

A

the presence of antibodies against T4 and/or Tg

18
Q

Interpret TRH response test results:
pre-TRH: TT4 in RI
post-TRH: TT4 in RI

A

Hyperthyroid (neoplastic cells don’t respond to TSH increase)

19
Q

How does size and unilateral vs bilateral status of a thyroid tumor relate to prognosis in dogs?

A

80% that are big enough to be found clinically are malignant

bilateral 16x more likely to met than unilateral

20
Q

What is the most common biochemical abnormality in cats with hyperthyroidism?

A

increased ALP (70%)

21
Q

What should you do if you suspect hyperthyroidism in a cat but the TT4 is normal?

A

run a fT4 and/or a TRH response test

22
Q

Fructosamine is higher or lower in hyperthryoid cats than normal cats?

A

lower (b/c accelerated albumin turnover)

23
Q

What % of hyperthyroid cats will have a normal TT4?

A

5-10%

24
Q

Suspect hyperthyroidism and get a decreased TT4. Interp?

A

not hyperthyroidism (99% sure)

25
Q

What % of cats with hyperthyroidism have an increased fT4?

A

98%

26
Q

What should you do if you get an increased TT4 in a dog?

A

run a test for thyroid antibodies to rule out thyroiditis that might be causing falsely increased TT4

27
Q

Why can’t you use fT4 alone to diagnose hyperthryoidism?

A

because you can have increased fT4 without an increased TT4 in euthyroid sick cats

28
Q

What is the concept of the TT3 suppression test?

A

give TT3 orally to see if it suppresses TSH secretion which decreases serum TT4

29
Q

Interpret results of a TT3 suppression test:
TT4 pre: in RI
TT4 post: below RI

A

normal cat (not hyperthyroidism)

30
Q

Why won’t a hyperthyroid cat have suppressed TSH levels with the T3 suppression test?

A

because their tumor is secreting TT4 and TT3 which already causes a suppressed TSH level (can’t suppress any further)

31
Q

Interpret results of a TT3 suppression test:
TT4 pre: in RI
TT4 post: in RI

A

hyperthyroid (not suppressing)

32
Q

What is the drawback of using the TRH response test?

A

TRH admin can cause tachycardia, salivation, tachypnea

33
Q

What is the drawback of using the TSH response test?

A

bovine TSH isn’t available anymore and human TSH is expensive

34
Q

Interpret endogenous TSH test results:
TT4: N
fT4: N
eTSH: decreased

A

hyperthryoidism (only use when you suspect hyperthyroidism but the screening tests aren’t definitive)

35
Q

In a dog with hypothyroidism that has a high TT4 from antibodies, will the fT4 be affected?

A

no not usually affected so should be low

36
Q

Myxedema is uncommon but pathognomonic for what?

A

hypothyroidism

37
Q

What is unique about sighthound TT4?

A

it is low normally so need to use a different test to diagnose hypothyroidism in them

38
Q

What would you expect in a case of goiter?
TT4-
fT4-
TSH-

A

TT4- decreased
fT4- decreased
TSH- increased

Thrall (4 decks)

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