Hypothyroidism Flashcards

1
Q

What releases TRH?

A

Hypothalamus

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2
Q

What releases TSH?

A

Anterior Pituitary

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3
Q

What are the three substances the thyroid gland produces?

A

T3
T4
Calcitonin

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4
Q
Which of the following is the most active form of thyroid hormone?
A) Bound T4
B) Bound T3
C) Free T4
D) Free T3
A

D
free forms are able to pass through cell membranes while the bound forms cannot do this, the active form of thyroid hormone= T3

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5
Q

List the components needed to make T4 aka thyroxine

A

Zinc, B1, B6, Tyrosine, Iodine, Vanadium, B2, Vitamin C

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6
Q

What are the two components needed to convert T4 to T3 (triiodothyronine)?

A

Progesterone and Se

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7
Q

80% of the circulating pool of thyroid hormone is composted of ____.

A

T4…so 20%= T3

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8
Q

Deiodination of T4 results in what?

A

Formation of reverse T3 which is inactive

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9
Q
Disease of the hypothalamus is said to be \_\_\_ hypothyroidism.
A) Primary
B) Secondary
C) Tertiary
D) Quaternary
A

C

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10
Q
\_\_\_\_ hypothyroidism accounts for 95% of cases.
A) Primary
B) Secondary
C) Tertiary
D) Quaternary
A

A

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11
Q
Most cases of primary hypothyroidism are due to?
A) Idiopathic atrophy
B) Lymphocytic thyroiditis
C) Congenital
D) None of the above
A

B
95%= lymphocytic or idiopathic
5%= secondary congenital/acquired or primary congenital

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12
Q
Which of the following treats hyperthyroidism in cats, with overuse causing hypothyroidism?
A) Glucocorticoids 
B) Soloxine
C) I131 
D) Methimazole
A

C

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13
Q
Which of the following does not occur in euthyroid sick syndrome?
A) Protein binding decreases 
B) Total T4 decreases
C) Free T4 is converted to rT3
D) TSH is decreased
A

D

is normal to increased

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14
Q

List 5 drugs or drug classes that can cause low T4

A

Glucocorticoids
Carprofen
Furosemide
Phenobarb/Sulfas

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15
Q
Which of the following is not a CS of hypothyroidism?
A) Hyperpigmentation
B) Pruritic alopecia
C) Weight gain 
D) Cretinism
A

B- not pruritic

other signs include failure to cycle in bitches, weak pups, decreased cardiac contracticility

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16
Q

Deposition of mycopolysaccharides or GAGs in the dermis causes myxedema as they are highly polar and attract water. Where do these most commonly deposit in hypothyroidism?

A

Around peripheral nerves–> can have neurological signs

17
Q

Deposition of GAGs in the ___ rarely occurs but can result in a myxedema coma

A

Brain

18
Q

Total T4 levels measure Free/bound T4 and also autoantibodies to T4. What can occur if there are autoantibodies present?
A) Falsely normal to elevated T4
B) Falsely low T4
C) Both

A

A

19
Q

What should be done if the animal has a low T4 and normal TSH?
A) Nothing, do not treat
B) Put the animal on a long term dose of levothyroxine
C) Look at the CBC and chemistry for other signs
D) None of the above

A

C

low T4 + anemia or low T4 + high cholesterol= points to hypothyroidism and allows for a more definitive diagnosis

20
Q
What test should be performed if the animal has a low normal T4 and you suspect hypothyroidism?
A) TSH stim test
B) fT4 by equilibrium dialysis
C) Measure anti-T4 autoantibodies
D) All of the above
A

B

21
Q
If there is a high T4 and you really think it is hypothyroidism which test should you run?
A) TSH stim test
B) fT4 by equilibrium dialysis
C) Measure anti-T4 autoantibodies
D) None of the above
A

BC

22
Q

The TSH stim test involves taking a pre injection sample and a post TSH injection sample 4-8 hrs later. Which of the following results points toward a hypothyroid dog?
A) Significant increase in post T4 value
B) Moderate increase in post T4 value
C) No increase in post T4 value

A

C

23
Q
When should serum T4 levels be rechecked?
A) 2 weeks post treatment
B) 1 month post treatment
C) 2 months post treatment
D) Any time
A

B- needs time to reach steady state in the body

24
Q
When should serum T4 levels be taken when the animal is on a BID dose?
A) 2-4 hours after first dose
B) 4-6 hours after first dose
C) 9-11 hours after first dose
D) 8-12 hours after first dose
A

B

Levels should be normal to slightly high

25
Q
When should serum T4 levels be taken when the animal is on a SID dose?
A) 2-4 hours 
B) 4-6 hours 
C) 9-11 hours 
D) 8-12 hours
A

D

looking for a peak

26
Q

If an animal on levothyroxine is experiencing PU/PD/PP, nervousness, aggression, panting, excess WL, or fever, what dose this indicate?

A

Over dose of medication- stop for a few days and decrease