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*OldPharm > Thyroid > Flashcards

Thyroid Flashcards

1
Q

3 hormones the thyroid gland secrete

A

Triiodothyronine (T3),t1/2 1-2 dys (9%)
Thyroxine (T4), t1/2 6-7 dys (90%)
Calcitonin

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2
Q

synthesis of thyroid hormones requires what?

A

iodine

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3
Q

what thyroid hormone is more potent?

A

T3 is 4x more potent

most of it is from peripheral conversion of T4 to T3

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4
Q

what inhibits the conversion of T3 to T4?

A

beta-blockers, corticosteroids, amiodarone

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5
Q

what produced thyrotropin-releasing hormone (TRH)

A

hypothalamus

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6
Q

what inhibit iodine uptake by the thyroid (can’t produce thyroid hormone as well)

A

cardiac glycosides
bromine
fluorine
lithium

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7
Q

when does TSH peak?

A

early morning

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8
Q

what impairs the coupling of 1 DIT and 1 MIT or 2 DIT’s to form T 3 and T4 ?

A

Sulfonylureas, thionamides

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9
Q

what proteins bind thyroid hormone?

A

Thyroid Binding Globulin (TBG)
Albumin
Thyroid Binding PreAlbumin (TBPA)

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10
Q

what blocks the release of Hormones following proteolytic cleavage from the thyroglobulin

A

high levels of iodide or lithium

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11
Q

how much of thyroid hormone is bound?

A

99% (only free hormone has biological effect)

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12
Q

what does thyroid hormone do?

A 
basal metabolic rate
influence growth through stimulation of growth hormones synthesis and action
body temp 
fetal development
cardiac rate and contractility
peripheral vasodilations
red cell mass and circulatory volume
respiratory drive
peripheral nerves (reflexes)
hepatic metabolic enzymes
bone turnover
skin and soft tissue effects
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13
Q

normal range of total T4? (free and bound)

A

4.5-12.5 mcg/dL

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14
Q

what is the normal TSH range?

A

0.4-5.5

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15
Q

what is a more reliable lab than total T4 and T3?

A

Free T4 (FT4)

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16
Q

when is sensitive TSH increased?

A

primary hypothyroidism

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17
Q

when is sensitive TSH decreased?

A

primary hyperthyroidism

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18
Q

what is elevated w/ an increased thyroid binding globulin?

A

total T4 is elevated

Total T3 is elevated

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19
Q

Serum TSH concentration above statistically defined upper limit of reference range
Serum free thyroxine within reference range

A

sub-clinical hypothyroidism

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20
Q

what is the biggest time sub-clinical hypothyroidism is significant?

A

pregnant women

increased risk of placental abrusption, pre term delivery

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21
Q

women w/ thyroid autoantibodies have an increased risk for what?

A

spontaneous abortion

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22
Q

do you tx for sub-clinical hypothyroidism?

A

definitely is pregnant

still unclear for other populations

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23
Q

S/S of hypothyroidism

A 
Tiredness
Lethargy, Muscle pains
Weight gain
Intolerance to cold
Dry skin, Coarse skin
Bradycardia
Mental impairment
Dry thinning hair
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24
Q

effects of hypothyroidism on CV system

A 
systolic dysfunction
reduced oxygen uptake during exercise
diastolic HTN
increased arterial stifness
increased total cholesterol and LDL 
insulin resistance
decreased fibrinolytic capacity
decrease activity of VW factor and factor VIII
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25
Q

what effect does hypothyroidism have on digitalis?

A

decreased volume of distribution

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26
Q

what effect does hypothyroidism have on insulin?

A

impaired degradation

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27
Q

what effect does hypothyroidism have on warfarin?

A

delayed catabolism of clotting factors

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28
Q

what causes primary hypothyroidism?

A 
hashimoto's Dz
iodine deficency 
iatrogenic hypothyroidism (radioactive iodine ingestion, post thyroidectomy)
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29
Q

Causes of secondary hypothyroidism

A 
pituitary decrease (TSH is low/normal and thyroid levels low
hypothalamic dz- TRH deficiency, very rare but due to cranial irradiation, trauma, neoplastic dz
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30
Q

risk factors for hypothyroidism?

A

pospartum women
family hx of autoimmune thyroid disorders
previous head and neck of thyroid irradiation or surgery
other autoimmune endocrine (DM1, adrenal insuff.)
non-endocrine issues (celiac dz, vitiligo, MS, pernicious anemia, trisomy 21)

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31
Q

S/S of hypothyroidism in elderly patients

A 
Hoarseness
Deafness
Confusion
Dementia
Ataxia
Depression
Dry skin
Hair loss
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32
Q

An autoimmune disease resulting in fibrosis of the thyroid gland, antibodies to TSH receptor
Selective destruction of thyroid gland ↓ thyroid hormone and ↑ TSH levels

A

Hashimoto’s thyroiditis

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33
Q

what is the most common cause of hypothyroidism?

A

hashimoto’s thyroiditis

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34
Q

Congenital (infantile) hypothyroidism results in…….

A

dwarfism and mental retardation (cretinism)

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35
Q

problem that occurs w/ hypothyroidism patients appear to have edema beneath skin. these patients will often present in a coma

A

myxedema

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36
Q

clinical symptoms of myxedema

A

Hypothermia
Advanced hypothyroid symptoms
Altered sensorium (from delirium to coma)

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37
Q

thyroid drug from beef or pork thyroid gland. Dose is in a grain (60 mcg of T4) but has unpredictable stability. not used very often

A

Thyroid USP Armour

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38
Q

purified pork thyroblobulin also does in a grain but is standardized biologically with a ratio of T4:T3

A

thyroglobulin

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39
Q

synthetic T4 medication that is a good choice as long as not on a drug that inhibits conversion of T4 to T3.

A

levothyroxine

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40
Q

synthetic T3, good if one a medicaiton that inhibits peripheral conversion of T4 to T3.

A

liothyronine

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41
Q

synthetic T4:T3 that is expensive.

A

liotrix

42
Q

ADRs of thyroid USP and thyroglobulin

A

allergic rxn

43
Q

DOC for hypothyroidism

A

levothyroxine

44
Q

a switch from synthroid to generic levothyroxine can be significant enough to what?

A

mess a patient up, the amounts in the tablets themselves can be slightly off

45
Q

Contraindications for levothyroxine

A

thyrotoxicosis

46
Q

adrs w/ levothyroxine

A 
arrhythmias
tachycardia
anginal pain
cramps
HA
restlessness
sweating
weight loss
osteoporosis
47
Q

monitoring w/ levothyroxine

A

TSH every 6-8 weeks until normalized then every 6-12 months

if dose change check in 2-4 months

48
Q

what drugs cause alter absorption w/ levothyroxine. take levothyroxine 2 hours before or 4 hours

A

Cholestyramine
Ferrous sulfate
Sucralfate
Aluminum hydroxide

49
Q

what drugs cause increased metabolism of levothyroxine

A

Rifampin
Phenytoin
Carbamazepine

50
Q

what interaction is there w/ oral contraceptives/ estrogen w/ levothyroine

A

Increase thyroid binding globulin, resulting in lower free thyroid hormone

51
Q

what drugs inhibits synthesis and release of thyroid hormone

A

lithium

52
Q

if a patient is on amoidoarone what drug should they recieve?

A

liothyronine

53
Q

Sodium salt of the naturally occurring levorotatory isomer of T3. used for Initial therapy of myxedema (skin disorder) and myxedema coma
Short-term suppression of TSH in patients undergoing surgery for thyroid cancer.
Patients w/5’-deiodinase deficiency who cannot convert T4 to T3 (or on amiodarone)

A

liothyronine sodium

54
Q

combo of T4 and T3 but isn’t more beneficial than levothyroxine.

A

liotrix (euthroid, thyrolar)

55
Q

tx for myxedema coma

A

IV bolus w/ levothyroxine
maintenance of IV levothyroxine then switch to PO
IV hydocortisone until adrenal supression is R/O
supportive therapy- ventilation, euglycemia, BP, body temp

56
Q

tx for congenital hypothyroidism

A

Initial therapy within 45 days of birth at 10-15mcg/kg/d, associated with improved IQ’s in treated infants
Dose progressively decreased to typical adult dose beginning 11-20 years

57
Q

tx for hypothyroidism in pregnancy?

A

levothyroxine- need an increase of dose (20%)

58
Q

hypothyroidism in pregnancy is associated w/ an increased risk of what?

A

still births

59
Q

when is levothyroxine especially important in pregnancy.

A

first 12 weeks as that is when thyroid hormone is only supplied by mom

60
Q

what is the cause of hyperthyroidism

A

Overproduction of endogenous hormone
Exposure to excess endogenous hormone
Elevated free and total T3, T4 or both serum concentrations

61
Q

S/S of hyperthyroidism

A 
Nervousness
Anxiety
Palpitations
Increased basal metabolic rate (BMR)
Weight loss
Increased appetite
Increased body temp (heat intolerance)
Sweating
Fine Tremor
Tachycardia
Classical ophthalmic signs
62
Q

what is the most common cause of hyperthyroidism?

A

Graves’ disease

63
Q

Autoimmune syndrome that includes hyperthyroidism, diffuse thyroid enlargement, myxedema, thyroid acropachy

A

Graves’ disease

64
Q

what form in graves’ disease?

A

antibodies against thyroid cell

IgG types antibodies against TSH that bind to and activate the receptor

65
Q

There is a disproportionate increase in T_ as compared to T_ in graves’

A

Disproportionate increase in T3 compared to T4

66
Q

complications of graves’ disease and pregnancy

A

sponataneous abortion
premature delivery
low birth weight
eclampsia

67
Q

what can cause subclinical or overt hyperthyroidism in pregancy

A

Inappropriate production of human chorionic gonadotropin (hCG)

68
Q

what is the treatment for Graves’ dz in pregnancy

A

PTU at lowest effective dose)

69
Q

a life threatening medical emergency characterized by:

Severe thyrotoxicosis, high fever (often > 103 F), tachycardia, tachypnea, dehydration, delirium-coma, N/V, and diarrhea

A

thyroid storm

70
Q

precipitating factors for a thyroid storm

A

Infection, trauma, surgery radioactive iodine treatment, withdrawl from antithyroid drugs

71
Q

tx for thyroid storm

A

suppression of thyroid hormone formation and secretions
anti-adrenergic therapy
administration of corticosteroids

72
Q

what are thioamides that are used to treat hyperthyroidism

A

Propylthiouracil (PTU)

Methimazole (Tapazole)

73
Q

what tioamide also inhibits D1 which deiodinates peripheral T4 to T3

A

PTU

74
Q

in patients w/ Graves dz what effects do thioamides also do?

A

immunosupressive effect

75
Q

indications for thioamides

A

Management of hyperthyroidism
Thyrotoxic crisis
In the preparation of patients for surgical subtotal thyroidectomy

76
Q

what thioamide is typically used due to fewer side effects and more potent, but potential for teratogen effects

A

Methimazole (MMI)

77
Q

ADRs w/ thioamides?

A 
agranulocytosis (baseline WBC count) 
hepatotoxicity
vasculitis 
rash, arthralgia, myalgia
cholestatic jaundice
LAD 
drug fever
psychosis
alopecia
78
Q

how does potassium iodine (KI) help to tx hyperthyroidism

A

causes inhibition of thyroid hormone secretion and blocks conversion of T4 to T3
reduces size and vascularity of the gland

79
Q

indications for iodines

A

Preoperatively for thyroidectomy (7-14 days)

Used after RAI (3-7 days), to allow RAI to concentrate in thyroid

80
Q

contraindications for iodines

A

not to breastfeeding or pregnant women

81
Q

ADRs of iodines

A

hypersensitivy rxn
lacrimation
conjuncitivits

82
Q

agent of choice for graves, toxic autonomous nodules, toxic multinodular goiters. will lead to hypothyroidism

A

radioiodine

83
Q

drug that may maybe used for temporary control of thyrotoxicosis in patients allergic to thioamides and iodine.

A

lithium carbonate

84
Q

what drugs are used to ameliorate thyrotoxic symptoms :palpitations, anxiety, tremor, heat intolerance. adjunct therapy

A

beta-adrenergic antagonists

85
Q

what are corticosteroids used for w/ thyroid problems

A

thyroiditis and thyroid storm

decrease thyroid action and immune response in graves’ disease

86
Q

indications for thyroidectomy

A

large glands, severe ophthalmopathy, lack of remission on treatment

87
Q

what must e done before a thyroidectomy

A

PTU or MMI until patient is euthyroid (6-8 weeks) followed by iodide x 10-14 days

88
Q

Adrs of thyroidectomy

A

Hyperthyroidism
Hypothyroidism
Hypoparathyroidism
Vocal cord abnormalities

89
Q

what drugs can interact w/ thyroid agents

A 
warfarin
lithium
Diabetes meds- dose adjustments 
potassium iodine (in some expectorants)
digoxin- may need dose adjustments 
amiodarone
CNS depressants
90
Q

what drugs cause decreased TSH

A 
Dopamine
Levodopa
Bromocriptine
Octreotide
Amphetamin
Glucorticoids:
  >0.5 mg/day
dexamethasone
  100 mg/day
Hydrocortisone
91
Q

what drugs cause increased TSH

A 
Metoclopramide
>1 mg/kg
amiodarone
Iodinated
Contrast Media
92
Q

what drugs cause increased Free T4

A 
IVFurosemide
>80mg/day
IV heparin
Amiodarone
Iodinated
contrastMedi
NSAIDS:
Salicylates
>2g/day
Salsalate
>1.5-3g/day
Diclofenac,
Naproxen
93
Q

what drugs decrease free T4

A

phenytoin

carbamazepine

94
Q

what rx products have iodides

A

Amiodarone
Radiocontrast dye
Povidone iodine
Iodinated glycerol

95
Q

what non-Rx things have iodides

A

Cough and cold
Kelp
Herbals
Dietary supplements/ weight loss products

96
Q

Develops within 3-8 weeks after exposure in up to 5% pts with exposure to iodine
Treatment with thioamides and beta blockers

A

iodine induced hyperthyroidism

97
Q

Up to 10% of amiodarone treated patients will develop

Treat with levothyroxine replacement

A

iodine induced hypothyroidism

98
Q

up to 50% of patients on lithium will develop what?

A

hypothyroidsm (monitor TSH)

tx w/ levothyroxine

99
Q

does stopping lithium allow a person to return to a normal thyroid state

A

no, not always

100
Q

what is a med for Hep C or in chemo that can cause induced thyroid disease (usually hypothyroidism). can occur within 6-8 weeks or 6-23 months

A

interferon alpha (IFNalpha)

101
Q

if you stop interferon alpha therapy will hypothyroidism resolve

A

yes (might take a few months)

*OldPharm (12 decks)

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