Hyperthyroidism

Question 1

T/F: A functional adenocarcinoma is the most common cause of hyperthyroidism in cats.

Answer 1

False

Question 2

Thyroid hormone is stored in the colloid as ____.

Answer 2

thyroglobulin

Question 3

Which of the following would be able to move across a cell membrane?
A) T4
B) T3
C) fT4
D) rT3

Answer 3

C

Question 4

Which of the following is the most active form of thyroid hormone?
A) fT4
B) T4
C) T3
D) None of the above

Answer 4

C

T3 is the active form! T4 must be converted to T3

Question 5

In order to enter the nucleus T3 must be in which form?
A) Reverse
B) Bound
C) Free
D) none of the above

Answer 5

C

Question 6

When T3 enters the nucleus it activates the following: Na/K pump, gluconeogenic enzymes, respiratory enzymes, myosin heavy chain, and B adrenergic receptors. Which of the following can occur?
A) Decreased glucose levels
B) Increased glucose levels
C) Increased muscle mass
D) Decreased muscle mass

Answer 6

BD

Question 7

T/F: Hyperthyroidism is the most common endocrinopathy of older cats.

Answer 7

True

Question 8

Which of the following signs are to be expected most commonly in a hyperthyroid cat?
A) Weight gain, tachycardia, unkempt coat
B) Bradycardia, PUPD, Vomiting/diarrhea
C) Hypertension, unkempt coat, PUPD
D) Hypotension, weight loss, tachycardia

Answer 8

C

also weight loss, tachycardia, vomiting/ diarrhea (hypermotility)

Question 9

A cat is displaying signs of weight loss with poor appetite, decreased activity, and lethargy. Which of the following is the most likely cause?
A) Hypothyroidism
B) Apathetic hyperthyroidism
C) Hyperthyroidism
D) Hyperadrenocorticism

Answer 9

B
this is uncommon, thought to be caused by concurrent dz + hyperthyroidism…prolonged tachycardia can lead to heart failure and these CS

Question 10

Term for massive release of thyroid hormones that can lead to extreme tachycardia, murmur/gallop, and hypertension that may cause retinal detachment

Answer 10

Thyroid storm= go slow to prevent this

Question 11

T/F: A high T4 + elevated AST is diagnostic of hyperthyroidism.

Answer 11

False- ALT

Question 12

T/F: Cats with hyperthyroidism often have dilute urine due to hypertension and polydipsia which can predispose them to UTIs.

Answer 12

True

more concentrated urine is antibacterial

Question 13

T/F: As cats age, their normalT4 levels increase.

Answer 13

False- they decrease, so a high end normal T4 may be seen as elevated for an older cat

Question 14

If you suspect a cat has hyperthyroidism but the T4 is normal what is your next step?
A) Start methimazole
B) Submit for a fT4 by eqd
C) Submit fora fT3
D) Repeat T4 in a few days or weeks

Answer 14

BD

Question 15

What step should be performed before performing a UPC?

Answer 15

Urinalysis/culture to rule out presence of protein due to infection instead of kidney dz

Question 16

What may be the reason for allowing a cat to have slightly higher than normal thyroid values?
A) To keep up metabolism
B) To maintain heart rate
C) To support the kidneys
D) All of the above

Answer 16

C
kidney dz can be unmasked once the blood pressure normalizes and GFR decreases, if thyroid levels are kept slightly higher more blood will perfuse the kidney and possibly prolong life

Question 17

What step should be performed before administering I131 or performing surgery?

Answer 17

administration of 30 days of methimazole and check kidney values

Question 18

What are two cons to surgical removal of a thyroid gland adenoma?

Answer 18

• Accidental removal of the parathyroid gland

- Removal of the entire thyroid gland= makes the hypothyroid

Question 19

Radioactive iodine (I-131) can be used to destroy the tumor. What are two cons and at least one pro of this treatment?

Answer 19

Cons
-Special boarding fees may be required
-Proper disposal of feces and urine is required
-Expensive up front
Pro
-Cats do not have to be treated daily for the rest of their lives–> ends up being cheaper in the long run

Question 20

Which of the following is the MOA of methimazole?
A) Inhibits conversion of T4 to T3
B) Inhibits conversion of T3 to T4
C) Inhibits unbinding of T4 from its protein
D) Inhibits synthesis of TH by blocking incorporation of iodine

Answer 20

D

Question 21

Which of the following is a possible side effect of methimazole?
A) Vomiting which can lead to anorexia
B) Bone marrow suppression
C) Excoriation on the head
D) All of the above

Answer 21

D

Question 22

Which of the following is a sign of feline hypothyroidism?
A) Weight loss
B) Weight gain
C) Decreased fur on temples/pinnae
D) Decreased fur on ventrum
E) all of the above

Answer 22

BC

Question 23

T/F: Canine thyroid tumors are most commonly functional.

Answer 23

false- non-functional

Question 24

Which of the following is true regarding canine thyroid tumors?
A) Most are functional adenomas
B) Most are non functional adenomas
C) Most are malignant and non functional
D) Most are malignant and functional

Answer 24

C= highly invasive

functional tumors are uncommon but can happen!!

Question 25

Which of the following is the best method in order to diagnose a thyroid mass?
A) FNA
B) Excision biopsy
C) Incisional biopsy
D) Nuclear imaging

Answer 25

B

D is not good because the tumors usually aren’t functional so they don’t light up