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.Pharmacology > Part 16: Thyroid Disorders > Flashcards

Part 16: Thyroid Disorders Flashcards

1
Q

thyroid hormones are involved in what physiologic processes (6)?

A
  1. metabolism
  2. energy expenditure
  3. body temp
  4. promote growth and differentiation of cells
  5. bone remodelling
  6. protein synthesis and degradation
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2
Q

higher levels of thyroid hormones tends to cause ____ (increased or decreased) metabolism

A

increased

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3
Q

t/f thyroid hormones can be increased to a pathologic level which can cause overactive cellular processes

A

t

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4
Q

by increasing energy expenditure & metabolism, thyroid hormones increase ____ utilization and _____ oxidation

A

glucose; fatty acid

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5
Q

thyroid hormones have ___ (sympatholytic or parasympatholytic) effects

A

sympath

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6
Q

what is the effect of thyroid hormones on heart rate

A

raise hr

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7
Q

thyroid hormone secretion is regulated by the ___ and ___ glands

A

hypothalamus & pituitary

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8
Q

thyroid hormones are typically secreted in parallel with ____ rhythms

A

circadian

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9
Q

at what time of day is the highest amount of thyrotropin released from the hypothalamus?

A

2-4 am, when most people are sleeping

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10
Q

TRH stimulates the pitutary gland to secrete ____

A

TSH

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11
Q

the release of TSH from the pituitary causes the release of 2 thyroid hormones ___ & ___

A

T3 & T4

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12
Q

TRH stands for

A

thyrotropin releasing hormone

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13
Q

what are 2 positive regulators of TRH?

A

psychosis & cold temperature

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14
Q

what is a negative regulator of TRH?

A

stress

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15
Q

what is a negative regulator of TSH?

A

cortisol (stress)

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16
Q

what is the only structural difference between T3 & T4?

A

one iodine group

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17
Q

which thyroid hormone has higher affinity for the thyroid hormone receptors?

A

T3

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18
Q

the majority of thyroid-related physiologic effects are the result of thyroid hormone receptors being activated by which hormone?

A

T 3

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19
Q

what enzyme in the follicular cells of the thyroid is responsible for thyroid hormone synthesis and storage of the hormones as thyroglobulin comblexes?

A

thyroid peroxidase

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20
Q

once the thyroid hormones are made, they are stored as ___

A

thyroglobulin complexes

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21
Q

thyroid hormones are made from dietary ___

A

iodine

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22
Q

t/f the thyroid gland is the only human organ that uses iodine

A

t

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23
Q

does the thyroid gland create small amounts of hormone PRN or does it makes lots and store it?

A

makes lots and stores it

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24
Q

when stimulated by TSH, the ____ is cleaved and thyroid hormones are released into circulation

A

thyroglobulin

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25
Q

which of the 2 thyroid hormones is secreted in greater amount?

A

t4

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26
Q

how does thyroid peroxidase make thyroid hormones?

A

adds iodine groups to tyrosine residues and groups 2 iodinated tyrosine together

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27
Q

thyroid hormones circulate in the blood, primarily bound to ____ protein

A

thyroid-binding globulin

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28
Q

T4 is taken up by target cells via _____ transporters

A

organis anionic (OAT)

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29
Q

when T4 is taken up by OATS into target cells, it is converted into ___ by

A

T3

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30
Q

what enzymes are responsible for turning T4 into T3

A

cellular deiodinases

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31
Q

T3 binds to thyroid hormone receptors in the ____ of target cells

A

nucleus

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32
Q

activation of nuclear thyroid hormone receptors alters gene ___, which results in increasded cellular ___ and ____

A

transcription; metabolism & activity

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33
Q

nuclear receptors are classed with intracellular receptors and are sometimes called _____

A

ligand-activated transcription factprs

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34
Q

T4 has a ____ (long or short) half-life

A

long

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35
Q

what is the rate limiting step in the process of thyroid causing physiologic effects?

A

the converesion of T4 to T3

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36
Q

T4 is almost like an endogenous _____drug

A

pro

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37
Q

what is the half-life of T4?

A

6-7 days

38
Q

hyperthyroidism presents as symptoms associated with ___ metabolic rate

A

increased

39
Q

hypothyroidism presents as symptoms associated with ___ metabolic rate

A

decreased

40
Q

the circulating thyroid hormones impose ____ feedback loops on the release of TSH and TRH

A

negative

41
Q

the 2 most common thyroid disorders are autoimmune diseases and are :

A
  1. graves (hyper)

2. hashimoto’s (hypo)

42
Q

graves disease is the most common clinical presentation of _____

A

hyperthyroidism

43
Q

in Grave’s disease, a stimulatory anti-body called _____ is made by the immune system and it will stimulate ____ receptors to promote thyroid hormone release

A

thyroid-stimulation immunoglobulin; TSH

44
Q

why can the thyroid-stimulating IG continue to cause the release of thyroid hormones even when a negative feedback loop is present?

A

it is not sensitive to the negative feedback loop

45
Q

Case: a patient presents with high levels of T4, but low levels of TSH, what is the likely diagnosis?

A

likely graves disease hyperthyroidism bc the IG would bind to the TSH receptor to promote more T4 even though there is a negative feedback loop to reduct the amount of TSH made

46
Q

in Grave’s disease ____ hormone is high and ___ and ___ hormones are low

A

T4; TRH and TSH

47
Q

what are some clinical symptosm of Grave’s disease/ hyperthyroidism?

A

fast heart rate, weight loss (despite eating more) , elevated body temp. Extreme cases can have bulging eyes, goiter, and tremour

48
Q

what causes a goiter?

A

increased production of thyroid hormone

49
Q

what causes bulging eyes in Grave’s disease?

A

inflammation & edema

50
Q

what are some long-term consequences of untreated hyperthyroidism?

A

osetoporosis, peridontal disease, increased risk for “thyroid storm” and thyrotoxic risk

51
Q

what is thyroid storm?

A

a life-threatening situation where there is a sudden onset of systemic symptoms such as sweating, raised body temp, increased HR , dyspnea, muscle weakness, and cognitive changes

52
Q

thyroid storm can be triggered by ____ during a prolonged period of uncontrolled hyperthyroidism

A

systemic triggers like an infection

53
Q

what is methimazole?

A

a thyroid hormone antagonist

54
Q

t/f there is typically a delay in onset of thyroid antagonsists and they are not always 100% successful in managing hyperthyroidism, but do reduce the production of thyroid hormones

A

t

55
Q

methimazole is an antagonist of _____ (enzyme)

A

thyroid peroxidase

56
Q

is methimazole a competitive or non-competitive inhibitor?

A

competitive

57
Q

methimazole reduces the ____ synthesis of thyroid hormones

A

de novo

58
Q

why do the effects of methimazole take several weeks to kick in?

A

bc the thyroid gland has a lot of thyroid hormones already stored and ready to go, so you need to wait until that supply has been depleted

59
Q

methimazole is part of the ___. class

A

thioamide

60
Q

thioamides like methimazole have what important consideration in pregnancy?

A

they may interfere with fetal thyroid hormone synthesis and can cause hypothyroidism in the fetus

61
Q

what is the typical approach to methimazole use in pregancy?

A

it is also risky to have too high thyroid hormone, so methimazole may be used in pregnancy, but doses and serum level of thyroid hormones will be closely monitored

62
Q

t/f thioamides cross the placemta

A

t

63
Q

what are some of the pregancy risks associated with hyperthyroidims?

A

spontaneous abortion, low birth weight, stillbirth, preeclampsia, and heart failure

64
Q

list 2 examples of more complete methods of reducing thyroid hormones?

A

destruction of the thyroid gland with radioactive iodine or surgical removal

65
Q

why is systemic radioactive iodine not Thatttt unsafe?

A

bc the thyroid gland is the only organ that takes it up and uses it, so only the thyroid will be destroyed

66
Q

is the treatment with radioactive iodine immediate for reducing thyroid hormone?

A

no, because there is still the stored hormone

67
Q

t/f radioactive iodine treatment results in a dose-dependent irreversible termination of thyroid hormone productio

A

t

68
Q

t/f most patients treated with radioactive iodine will need surgical removal later bc it is difficult to know the exact dose needed of the iodine to completely inhibit the thyroid

A

t

69
Q

t/f the removal of the thyroid gland puts patients in a hypothyroid state and will require supplementation

A

t

70
Q

what is hypothyroidism?

A

thyroid hormone levels are too low to properly maintain metabolic and cellular functions

71
Q

what is Hashimoto’s thyroditis?

A

a form of hypothyroidim caused by an autoimmune disorder in which the autoantibody destroys the thyroid gland

72
Q

t/f Hashimoto’s results in low thyroid hormone levels despite the hypothalamus and pituitary calling for more release

A

t

73
Q

Case: patient is persistently cold and tired, gaining weight despite eating well, her T4 is low and TSH is high

A

she has hyperthyroidism

74
Q

which sex has higher rates of hypothyroidism?

A

female

75
Q

is hypothyroidism more common in younger or older people/

A

older

76
Q

hypothyroidism during development will have what effect on growth?

A

slowed growth

77
Q

the heart rate and BP of hypothyroid patients will be ____ (higher/lower) than normal

A

lower

78
Q

edema and enlarged tongue are symptoms of what type of thyroid disorder?

A

hypo

79
Q

what is a common drug used to treat hypothyroidism?

A

levothyroxine (synthroid)

80
Q

what is levothyroxine?

A

a synthetic T4 hormone

81
Q

t/f the doses of synthroid need to be titrated over time

A

t

82
Q

is the GI absorption os synthroid affected by food?

A

yes

83
Q

which has a longer half-life, synthroid, T4, or liothyroxine

A

synthroid

84
Q

the TH effects of synthroid are controlled by the physiological conversion to ____-

A

T3

85
Q

what is Liothyroxine and why is it not preferred?

A

a synthetic T3 hormone, not preferred bc it has higher risk for hyperthyroidism

86
Q

why is the risk for hyperthyroidism higher in liothyronine than synthroid?

A

bc liothyronine skips the rate limiting step of converting T4 to T3

87
Q

do patients continue thyroid medications for life?

A

yes

88
Q

can lifestyle changes affect the dose of thyroid drugs needed?

A

yes

89
Q

the biovailabilty of synthroid is increased on a full or empty stomach?

A

empty

90
Q

the demand for thyroid hormones is ofetn ___ (higher or lower) during pregnancy

A

higher

91
Q

people on any type of thyroid medication need routine ____

A

blood wrk

.Pharmacology (55 decks)

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