Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Internal medicine (small) > Thyroid glands > Flashcards

Thyroid glands Flashcards

(66 cards)

Start Studying
1
Q

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

A

follicular
parafollicular (medullary/C) cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what do follicular cells of the thyroid produce?

A

thyroid hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what do parafollicular/medullary cells of the thyroid produce?

A

calcitonin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is thyroid hormone secretion regulated by?

A

hypothalamic-pituitary-thyroid axis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what does the hypothalamus release as part of the hypothalamic-pituitary-thyroid axis?

A

thyrotropin releasing hormone (TRH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does thyroid releasing hormone act on?

A

pituitary gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what does the pituitary gland release as part of the hypothalamic-pituitary-thyroid axis?

A

thyroid stimulating hormone (TSH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what does TSH act on?

A

thyroid gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does the thyroid gland produce as part of the hypothalamic-pituitary-thyroid axis?

A

T4 (thyroxine) and T3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what effect does T4 nd T3 have on the pituitary gland and hypothalamus?

A

negative feedback to prevent the release of TRH and TSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what happens to T4 in peripheral tissue?

A

synthesised to T3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

does the thyroid produce more T3 or T4?

A

T4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

is T4 or T3 more biologically active?

A

T3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how is most T3 and T4 transported?

A

bound to plasma proteins (globulins)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the effect of thyroid hormones on metabolism?

A

increased metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the functions of thyroid hormones?

A

increases metabolic rate of tissue
positive inotrope/chronotrope
increase number/affinity of beta-adrenergic receptor
enhance response to catecholamines
catabolic effect of muscle and adipose tissue
stimulate erythropoiesis
regulate cholesterol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what effect do thyroid hormones have on the heart?

A

positive inotrope and chronotrope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is hypothyroidism?

A

clinical syndrome resulting from deficiency of T3 and T4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how does thyroid hormone increasing the number/affinity of beta-adrenergic receptors and enhancing their response to catecholamines effect the heart?

A

increases heart rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what animals is hypothyroidism most commonly seen in?

A

middle/older aged dogs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what causes congenital hypothyroidism?

A

thyroid hypoplasia, aplasia or dyshormonogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

how can the pituitary gland cause congenital hypothyroidism?

A

panhypopituitarism causes TSH deficiency leading to thyroid hormone deficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what breed is panhypopituitarism seen in?

A

German shepherds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

is acquired or congenital hypothyroidism more common?

A

acquired

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what are the two types of acquired hypothyroidism?
primary (due to thyroid gland) secondary (due to pituitary gland) tertiary (due to hypothalamus)
26
what are some causes of primary hypothyroidism?
lymphocytic thyroiditis idiopathic atrophy thyroid neoplasia
27
what type of disease is lymphocytic thyroiditis?
immune-mediated
28
what are the clinical signs of hypothyroidism?
metabolic - lethargy, obesity, exercise intolerance, cold intolerance dermatological - thinning/alopecia, poor coat quality, skin hyperpigmentation, pyoderma diarrhoea, bradycardia, altered oestrus cycle, neuropathy
29
can haematology and biochemistry diagnose hypothyroidism?
no - may may point towards it or help to rule in/out other disease
30
what will be the features on haematology of a dog with hypothyroidism?
mild normocytic normochromic non-regenerative anaemia
31
what changes will be seen on biochemistry of a dog with hypothyroidism?
hypertriglyceridaemia hypercholesterolaemia mildly increased CK mildly increased ALP and ALT fructosamine increase
32
how does the serum of a dog that has hypothyroidism appear?
milky colour due to hypertriglyceridaemia
33
why are hypothyroidism dogs hypertriglyceridaemic?
because they have less lipid metabolism so it remains in the blood
34
why does ALP and ALT mildly increase with hypothyroidism?
lipid storage in the liver due to decreased metabolism causing damage
35
why does CK mildly increase in hypothyroidism cases?
muscle catabolism
36
how is required to diagnose hypothyroidism?
thyroid hormone testing
37
what ways can thyroid hormone be measured?
total T4 free T4 total T3 TSH
38
what test results confirm hypothyroidism?
increased TSH and decreased total/free T4 (thyroxine)
39
what dynamic function tests are available for thyroid hormone testing?
TRH or TSH stimulation
40
what two things have to be measure to confirm hypothyroidism?
TSH and T4
41
what is the most common test for hypothyroidism?
total T4
42
what are some possible reasons for false positives when using total T4 to test for hypothyroidism?
can be low due to non-thyroidal illness some drugs can cause it to be low older dogs can have low T4
43
what breeds have low-normal values of total T4?
greyhounds
44
what happens to free T4 if the sample is left out?
concentration significantly increases if left at room temperature for prolonged periods
45
what can cause a false increased in free T4?
severe lipaemia samples stored at room temperature
46
how will TSH be effected in hypothyroidism?
increased (sometimes normal)
47
what can cause increases in TSH other than hypothyroidism?
recovery from non-thyroid illness use of sulphonamides
48
what should TSH always be measured with?
T4
49
what can thyroid hormone autoantibodies be used to provide evidence for?
provide evidence of immune reaction to the thyroid gland (doesn't diagnose hypothyroidism)
50
how can thyroid hormone autoantibodies effect total T4/T3?
can cause increases in total T3 or T4 because tests can misinterpret the autoantibodies as T3 or T4
51
how does prednisolone effect thyroid hormones?
causes decrease total and free T4 normal or decreased TSH
52
how does phenobarbital effect thyroid hormones?
decrease total and free T4 increased TSH
53
how does sulphonamide effect thyroid hormone?
decreased total and free T4 increased TSH
54
what drugs cause hypothyroidism?
sulphonamides
55
how do sulphonamides cause hypothyroidism?
inhibits thyroid peroxidase which is the enzyme used to release thyroid hormone from the thyroid
56
how is hypothyroidism treated?
levothyroxine (thyroid hormone supplementation)
57
how long is the treatment cause of levothyroxine for hypothyroidism?
life long
58
why does care need to be taken when treating hypothyroidism in cases that have concurrent cardiac problems?
treating will cause increased heart rate which could compromise the heart
59
how is the response to hypothyroidism treatment monitored?
look at clinical signs measure total T4 (4-6 hours post treatment)
60
how long should it take the metabolic signs of hypothyroidism to resolve after treatment?
couple of weeks
61
what are some common complications of hypothyroidism?
neurological - generalised myopathy, megaoesophagus, laryngeal paralysis hyperlipidaemia, atherosclerosis myxoedema coma
62
is hypothyroidism more common in cats or dogs?
dogs (rare in cats)
63
what is the most common cause of hypothyroidism in cats?
iatrogenic - over treatment of hyperthyroidism, bilateral thyroidectomy, radioactive iodine treatment
64
how is hypothyroidism of cats diagnosed?
canine TSH
65
how do most cats present with hypothyroidism? (very uncommon)
goitre
66

Internal medicine (small) (33 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions