Internal medicine (endocrine)

Question 1

what are the thyroid gland?

Answer 1

two distinct nodes either side of trachea

Question 2

what are the two types of endocrine cells in the thyroid gland?

Answer 2

follicular
parafolliculuar (medullary)

Question 3

what do follicular cells of the thyroid gland produce?

Answer 3

thyroid hormones

Question 4

what do the parafollicular cells of the thyroid gland produce?

Answer 4

calcitonin

Question 5

what regulates the thyroid hormone production?

Answer 5

hypothalamic pituitary thyroid axis

Question 6

what produces the stimulation for the thyroid to produce hormones?

Answer 6

pituitary gland (TSH)

Question 7

what does the thyroid gland produce when stimulated by TSH?

Answer 7

lots of T4 and small amounts of T3

Question 8

what is T4?

Answer 8

thyroxine

Question 9

what happens to T4 in peripheral tissue?

Answer 9

converted to T3

Question 10

what effect does T3 have on the pituitary gland?

Answer 10

negative feedback causing less production of TSH

Question 11

what structures does T3 have a negative feedback effect on?

Answer 11

hypothalamus and pituitary gland

Question 12

what substance does thyroid hormone synthesis require?

Answer 12

iodine

Question 13

which thyroid hormone is biologically active?

Answer 13

T3

Question 14

what is the function of thyroid hormones?

Answer 14

increases metabolic rate and oxygen consumption of tissues
positive inotropc/chronotropic effects on heart
stimulate erythropoiesis
regulate cholesterol synthesis/degredation

Question 15

what is the function of thyroid hormones?

Answer 15

increases metabolic rate and oxygen consumption of tissues
positive inotropc/chronotropic effects on heart
stimulate erythropoiesis
regulate cholesterol synthesis/degradation
catabolic effect on muscles/adipose tissue

Question 16

is hypothyroidism more common in dogs or cats?

Answer 16

dogs

Question 17

what are some possible causes of congenital hypothyroidism?

Answer 17

thyroid hypoplasia, aplasia, dyshormonogenesis
disproportionate dwarfism

Question 18

what are the primary causes of acquired hypothyrodisim?

Answer 18

lymphocytic thyroiditis
idiopathic atrophy
aggressive thyroid neoplasia

Question 19

what causes secondary/tertiary acquired hypothyroidism?

Answer 19

defects in the pituitary or hypothalamus

Question 20

what are the clinical signs of hypothyroidism?

Answer 20

metabolic - lethargy, obesity, exercise intolerance
dermatology - hair thinning, alopecia, poor quality coat, skin hyperpigmentation, pyoderma

Question 21

what are some changes in haematology that indicate hypothyroidism?

Answer 21

mild normocytic normochromic non-regenerative anaemia
hypercholesterolaemia
hypertriglyceridaemia

Question 22

what is done to diagnose hypothyroidism?

Answer 22

thyroid hormone testing - increased TSH and decreased total/free T4

Question 23

what measurements can be done for thyroid hormones?

Answer 23

total T4
free T4
total T3
TSH

Question 24

what breeds is T3 a better test for thyroid function?

Answer 24

sighthounds and sled dogs

Question 25

what can cause an artifactual increase of free T4?

Answer 25

storing at room temperature for prolonged period