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Pharmacology 200 > 3 - thyroid > Flashcards

3 - thyroid Flashcards

1
Q

what the role of thyroid hormones

A

growth, development and maintenance of tissues, metabolic and respiratory rate

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2
Q

what is the structure of thyroid hromones

A

conjugated iodinated tyrosines

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3
Q

what are the major forms of thyroid hormones

A

T3 and T4

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4
Q

what is the ratio of T4 to T3 release

A

14:1

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5
Q

is T3 or T4 the active form

where is it converted

A

T3 is active, converted in periphery

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6
Q

where does T3 bind

A

to nuclear receptors to activate certain genes

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7
Q

where are the T3 and T4 receptors located

A

in nearly all human tissue

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8
Q

why cant you measure T3 and T4 for disorders

A

they are regulated by negative feedback, its easier to measure TSH

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9
Q

which disorder is high TSH

A

hypothyroidism (no negative feegback)

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10
Q

which disorder is low TSH

A

hyperthyroidism (strong negative feegback)

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11
Q

what is TSH

A

thyroid stimulating hormone

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12
Q

how does TSH change with a two fold change in free T4 and T3

A

100 fold change

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13
Q

what is hypotheyroidism

A

clinically significant reduction in thyroid hormone production

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14
Q

what is the most common cause of hypotheyroidism

A

auto-immune

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15
Q

is hypotheyroidism or hypertheyroidism more common

A

hypotheyroidism (5-6X)

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16
Q

are women or men more affected by hypotheyroidism

A

women (7 - 10X)

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17
Q

what are some symptoms of hypotheyroidism

A

fatigue, cold dry skin, hair loss, brittle laids, hypotension, bradycardia

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18
Q

what is the treatment of hypotheyroidism

A

supplement T4 via levothyroxine

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19
Q

what was the historical treatment of hypotheyroidism

A

chew cow and pig thyroid glands

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20
Q

why is chewing a thyroid gland not very safe

A

there can be a variability in amounts of T3 and also other harmful substances

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21
Q

what is levothyroxin

A

T4 to treat hypotheyroidism

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22
Q

why give the body T4 and not T4

A

so the body can convert it to T3 as needed

if it was just T3 then peripheral tissues lose the ability to control local metabolic rates

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23
Q

what is the half life of T4

A

7-10 days

smooth

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24
Q

what is the half life of T3

A

24h

peaks bad

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25
what is thyrotoxicosis
too much T3 (not necessarily from the gland)
26
what is hyperthyroidism
increased thyroid hormone synthesis and secretion from the thyroid gland
27
what is the most common cause of hyperthyroidism
Graves disease
28
what is Graves disease
autoimmune disease where antibodies bind to the TSH receptor on thyroid gland follicles resulting in unregulated stimulation of thyroid hormone synthesis
29
what are the symptoms of hyperthyroidism
high metabolitic rate, cardiovascular disease, osteoperosis, agitation, insomnia, muscle wasting
30
what is opthalmopathy
when the eyes pop out due to the antibodies from graves disease triggering TSH receptor in eyes
31
what happens to beta adrenergic receptor expression in hyperthyroidism
increased beta adrenergic expression, increased cAMP, reduce Gi
32
what is a way to treat hyperthyroidism using radioactivity
radioactive iodine
33
how does radioactive iodine work (131I)
partially destroy the thyroid gland (very selective, accumulation)
34
how does the radioation kill the thyroid
energy kills follicular less, gamma rays pass through tissue with no damage, beta particles damage surrounding tissue
35
what do beta particles do with radioactive iodine
damage surrounding tissue
36
what do gamma rays do with radioactive iodine
pass through tissue with no damage
37
how long does radioactive iodine take to work and why
6-18 weeks because there is already lots of stored hormone
38
how can radioactive iodine be used for diagnosis
detect for abnormalities in the thyroid gland
39
what is toxic adenoma
benign tumor
40
what is the most common cause of hyperthyroidism
Graves disease
41
what is Graves disease
autoimmune disease where antibodies bind to the TSH receptor on thyroid gland follicles resulting in unregulated stimulation of thyroid hormone synthesis
42
what are the symptoms of hyperthyroidism
high metabolitic rate, cardiovascular disease, osteoperosis, agitation, insomnia, muscle wasting
43
what is opthalmopathy
when the eyes pop out due to the antibodies from graves disease triggering TSH receptor in eyes
44
what happens to beta adrenergic receptor expression in hyperthyroidism
increased beta adrenergic expression, increased cAMP, reduce Gi
45
what is a way to treat hyperthyroidism using radioactivity
radioactive iodine
46
how does radioactive iodine work (131I)
partially destroy the thyroid gland (very selective, accumulation)
47
how does the radioation kill the thyroid
energy kills follicular less, gamma rays pass through tissue with no damage, beta particles damage surrounding tissue
48
what do beta particles do with radioactive iodine
damage surrounding tissue
49
what do gamma rays do with radioactive iodine
pass through tissue with no damage
50
how long does radioactive iodine take to work and why
6-18 weeks because there is already lots of stored hormone
51
how can radioactive iodine be used for diagnosis
detect for abnormalities in the thyroid gland
52
what happens differently in toxic adenoma and nodeular goiter
they produce hormones regardless of TSH signal
53
why are the thyroid abnormaties detectable
because they synthesize excess hormones so they use a lot of the radioactive iodine
54
how can iodine be used to track metastasis
because iodine if it spreads, they still use it to make the hormones so iodine will show up in a scan
55
what are antithyroid drugs used for
reducing thyroid hormone levels
56
what group of drugs are antithyroid drugs
thiourelyene
57
what is an important part of antithyroid drugs' structure
thiocarbamide (S-C-N)
58
how do antithyroid drugs work
they inhibit the enzyme peroxidase, which results in less hormone synthesis
59
what is the halflife of propylthiouracil
1.5hours
60
what is the halflife of methimazole
6 hours
61
why is the duration of antithyroid drugs longer than their halflives
because the thyroid gland accumulates the drugs
62
why is the onset of antithyroid drugs effect often delayed
due to large store of hormone in follicles
63
what are the two antithyroid drugs
propylthiouracil and methimazole
64
which antithyroid drugs has to be dosed more than once a day
propylthiouracil
65
which antithyroid drugs can be dosed once a day
methimazole
66
which antithyroid drug inhibits conversion of T4 to T3 | how
propylthiouracil inhibits the activity of T4 deiodinase
67
which antithyroid drug is preferred due to less hepatotoxicity
methimazole
68
what do the antithyroid drugs do to the immune system | why may this be helpful
overall supression good if autoimmunity is the caus
69
how does Iodine transport into the follicle
Na+/I- symporter proteins
70
what is pendrin
a transport protein that pumps accumulated iodine into the follicle
71
what does thyroid peroxidase do (2 things)
``` oxidize iodide(-1) to form iodine (0) AND conjugates MIT and DIT within thyroglobulin to form T3 and T4 ```
72
what is iodide organification
iodine added to tyrosine (in thyroglobulin)
73
what happens once iodinated thyroglobulin is formed
taken up by cells via endocytosis
74
what happens once thyroglobulin is degraded
T4 and T3 are released and secreted
75
what is the structure of thyroid peroxidase (TPO) | where is it found
heme group with bound iron, a membrane-bound protein
76
how does thyroid peroxidase (TPO) make TPO-O ox
uses H2O2
77
how does thyroid peroxidase (TPO) make TPO-I ox
add iodide (I-)
78
what happens to TPO-I ox
the iodine is donated to tyrosine in the thyroglobulin protein to form either DIT or MIT
79
what is the mechanism of action of antithyroid drugs
the sulfylhydryl groups of these drugs is iodinated instead of the thyroglobulin (competitively)
80
what causes methylimidazole to form
iodinated drugs can bind to one another with disulfide link
81
what is the most serious side effect of antithyroid drug use
agranulocytosis (autoimmune)
82
when do most cases of agranulocytosis occur and which %
0,37 and 0,35 | within 90 days, but sometimes after a year
83
what are other risks other than agranulocytosis for antithyroid drugs
hepatotoxicity, vasculitis, arthritis

Pharmacology 200 (29 decks)

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