Hypothyroidism Flashcards
What releases TRH?
Hypothalamus
What releases TSH?
Anterior Pituitary
What are the three substances the thyroid gland produces?
T3
T4
Calcitonin
Which of the following is the most active form of thyroid hormone? A) Bound T4 B) Bound T3 C) Free T4 D) Free T3
D
free forms are able to pass through cell membranes while the bound forms cannot do this, the active form of thyroid hormone= T3
List the components needed to make T4 aka thyroxine
Zinc, B1, B6, Tyrosine, Iodine, Vanadium, B2, Vitamin C
What are the two components needed to convert T4 to T3 (triiodothyronine)?
Progesterone and Se
80% of the circulating pool of thyroid hormone is composted of ____.
T4…so 20%= T3
Deiodination of T4 results in what?
Formation of reverse T3 which is inactive
Disease of the hypothalamus is said to be \_\_\_ hypothyroidism. A) Primary B) Secondary C) Tertiary D) Quaternary
C
\_\_\_\_ hypothyroidism accounts for 95% of cases. A) Primary B) Secondary C) Tertiary D) Quaternary
A
Most cases of primary hypothyroidism are due to? A) Idiopathic atrophy B) Lymphocytic thyroiditis C) Congenital D) None of the above
B
95%= lymphocytic or idiopathic
5%= secondary congenital/acquired or primary congenital
Which of the following treats hyperthyroidism in cats, with overuse causing hypothyroidism? A) Glucocorticoids B) Soloxine C) I131 D) Methimazole
C
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
D
is normal to increased
List 5 drugs or drug classes that can cause low T4
Glucocorticoids
Carprofen
Furosemide
Phenobarb/Sulfas
Which of the following is not a CS of hypothyroidism? A) Hyperpigmentation B) Pruritic alopecia C) Weight gain D) Cretinism
B- not pruritic
other signs include failure to cycle in bitches, weak pups, decreased cardiac contracticility
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?
Around peripheral nerves–> can have neurological signs
Deposition of GAGs in the ___ rarely occurs but can result in a myxedema coma
Brain
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
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
C
low T4 + anemia or low T4 + high cholesterol= points to hypothyroidism and allows for a more definitive diagnosis
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
B
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
BC
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
C
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
B- needs time to reach steady state in the body
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
B
Levels should be normal to slightly high
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
D
looking for a peak
If an animal on levothyroxine is experiencing PU/PD/PP, nervousness, aggression, panting, excess WL, or fever, what dose this indicate?
Over dose of medication- stop for a few days and decrease
