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Endocrine - Troutmanm > Thyroid > Flashcards

Thyroid Flashcards

1
Q

What does the thyroid gland regulate?

A

regulates the metabolic rate of the body

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2
Q

Complete lack of thyroid secretion results in the basal metabolic rate of the body to decrease by

A

40 to 50 %

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3
Q

Extreme excesses of thyroid secretion can increase basal metabolic rate by

A

60 to 100% above normal

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4
Q

What shape is the thyroid gland?

A

butterfly shaped

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5
Q

Where is the thyroid gland located?

A

Located immediately below the larynx, anterior and to each side of the trachea

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6
Q

What is the size of the endocrine gland?

A

One of the largest endocrine glands, weighs 15 to 20 grams in adults

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7
Q

What hormones does the thyroid secrete?

A 
Thyroxine (T4) 
Triiodothyronine (T3) 
Reverse T3 (rT3)-inactive
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8
Q

The thyroid also produces calcitonin, and important hormone is ______ regulation

A

calcium

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9
Q

Thyroid gland is made of follicles of _______ surrounding a colloid matrix

A

cuboidal epithelial cells

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10
Q

What is required for thyroid hormone synthesis?

A

iodine

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11
Q

What are the most important thyroid hormones for metabolic control

A

T3 and T4

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12
Q

how does T3 and T4 compare to each other

A

The functions of these two hormones are qualitatively the same, but they differ in their rapidity and intensity of action

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13
Q

The thyroid secretes 93% _____ and 7% ______, though nearly all is converted to ___ in the tissues

A

thyroxine (T4)
triiodothyronine (T3)
T3

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14
Q

T3 is 4x more potent than T4, but is

A

more scarce and is cleared more rapidly

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15
Q

Thyrotropin-releasing hormone (TRH) is released by the ______

A

hypothalamus

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16
Q

What does TRH cause release of?

A

TRH causes release of thyroid-stimulating hormone (TSH) by the anterior pituitary

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17
Q

What dies TSH cause release of?

A

TSH causes release of thyroid hormones(TH-both T3 and T4) from the thyroid gland

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18
Q

Only free TH is active, but, over 99% is bound to protein, either _____ or _____

A

Thyroxine binding globulin (TGB) or albumin

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19
Q 
Thyroid hormone (TH) is slowly released from \_\_\_\_\_
TH is taken up by \_\_\_\_\_\_
A

protein

peripheral tissues

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20
Q

Peripheral tissues contain enzymes that convert T4 to T3, ___ is more metabolically active

A

T3

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21
Q

TH activate intracellular processes, what do these increase?

A

increase gene transcription, protein and enzyme production which increase metabolic rate

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22
Q

TH increases the size and number of ______, which are the energy generators of cells

A

mitochondria

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23
Q

T/F: Thyroid hormones have important effects on many mechanisms throughout the body. It is likely that all cells in the body are targets for thyroid hormones

A

True

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24
Q

In general, what do thyroid hormones effect?

A

metabolism, growth and development

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25
Q

What are they effects of increased thyroid hormone (5)

A

Stimulation of Carbohydrate Metabolism
(Increases uptake of glucose by cells and by GI tract
Enhances glycolysis, gluconeogenesis, and insulin secretion)

Stimulation of Fat Metabolism
(Mobilizes lipids, decreases fat stores, decreases cholesterol)

Increased Requirement for Vitamins
(Vitamins needed for increased enzyme synthesis)

Increased Basal Metabolic Rate
(Increases metabolism in almost all cells)

Decreased Body Weight
(Does not always occur because appetite is also increased)

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26
Q

Thyroid effects on CV

A

Increased BF secondary to vasodilation
Increased C.O.
Increased heart strength and HR
Normal MAP (increased SBP, decreased DBP, increased PP)
Increased respirations (because more CO2 produced)
Increased number and affinity for B-adrenergic receptors
DECREASED number of cardiac alpha-adrenergic receptors

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27
Q

Thyroid effect in CNS

A

Increased mentation, but also increased anxiety and neurosis

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28
Q

Thyroid effects on muscle

A

muscles more vigorous, become more weak with protein catabolism

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29
Q

Thyroid effects on sleep

A

Causes exhaustive/excitatable effects, constantly tired but cant sleep

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30
Q

Thyroid effects on endocrine system

A

Increases both secretion by glands, but also need for hormone from peripheral tissues

31
Q

thyroid effects on reproduction and sexual effects

A

LACKof thyroid hormone causes loss of libido

EXCESS can cause impotence

Inconsistent menstrual changes occur

32
Q

What is hypothyroidism?

A

Hypothyroidism is a condition where the thyroid does not make an adequate amount of thyroid hormones

33
Q

What are symptoms of hypothyroid hormone

A 
COLD INTOLERANCE	
Weight Gain
Constipation			
Decreased taste and smell
DEPRESSION
Hoarseness
FATIGUE		
Menstrual Disorders
Muscle orJOINT PAIN		
Puffy face, hands, feet
Paleness			
Slow Speech
THIN, BRITTLE FINGERNAILS	
Thickening of skin 
Thin, brittle hair		
Thinning of Eyebrows
WEAKNESS
34
Q

*** What is primary hypothyroidism?

A

T3, T4 are not produced because of problems with the THYROID GLAND
Most commonly due to autoimmune Hashimoto’s thyroiditis and surgical removal of thyroid tissue
Other causes include inadequate dietary iodine (rare), radiation exposure, lithium, surgery

35
Q

*** What is secondary hypothyroidism?

A

Inadequate T3, T4 due to TSH not being released from the pituitary

(5-10% of cases)

36
Q

*** What is tertiary hypothyroidism?

A

Inadequate T3, T4 due to Thyrotropin Releasing Hormone (TRH) from hypothalamus

(<5% of cases)

37
Q

When happens when hypothyroidism occurs in infancy?

A

leads to mental retardation and growth deficits (cretinism)

38
Q

What is the most severe form of hypothyroidism?

A

mydexa come

39
Q

what is mydexa coma?

A

Rare condition

Triggered by illness, infection, exposure to cold, medicines

Symptoms include coma, decrease breathing, decrease blood sugar, decreased blood pressure, and decreased temperature

40
Q

What is the standard test for thyroid gland function?

A

Serum T4 assay

Total T4 elevated in 90% of people with hyperthyroidism
Total T4 low in 85% of people with hypothyroidism
Affected by levels of TBG

41
Q

How are blood levels are T3 and T4 in hypothyroidism?

A

low

42
Q

how are blood levels of TSH in hypothyroidism?

A

high

43
Q

Blood levels of ___ are high in euthyroid sick states (critical illness)

A

rT3

44
Q

What is Synthroid?

A

T4 (and most commonly used)

45
Q

What is armor thyroid? (this is a med)

A

contains both T3 and T4

46
Q

should elective surgery happen when a patient has hypothyroidism?

A

Elective surgery should be postponed until euthyroid state is achieved (not always done)

47
Q

hypothyroidism and anesthesia associated problems

A

Lethargy, hypotension, bradycardia, CHF, gastroparesis, hypoglycemia, hypothermia, hypoventilation, hyponatremia

48
Q

Anesthetic management for when putting a hypothyroid patient under anesthesia

A

Be aware of the “crash on induction” possibility

Ketamine frequently used on induction

Volatile agents not recommended due to the sensitivity of the myocardium to depression

Pancuronium/Rocuronium have
vagolytic/sympathomimetic effects

Aline is indicated with PA catheter in setting of cardiac failure

49
Q

What is hyperthyroidism?

A

Hyperthyroidism is a condition of thyroid gland overactivity

50
Q

What is thyroiditis?

A

Thyroiditis is inflammation of the thyroid which causes release of excessive hormone but not increased production

51
Q

what is thyrotoxicosis

A

oversupply of thyroid hormones on peripheral tissues

52
Q

What are symptoms of thyrotoxicosis/hyperthydroidism

A 
Palpitations			
Heat Intolerance
Nervousness			
Insomnia
Breathlessness		
Increased bowel movements
Fatigue			
Light or absent menstrual periods
Tachycardia			
Trembling Hands
Muscle Weakness		
Warm moist skin
Hair Loss			
STARING GAZE (Exophthalmos)
53
Q

How do symptoms of hyperthyroidism come on?

A

slowly

54
Q

What is the most common cause of hyperthyroidism

A

Grave’s disease (60-90% of cases) which is an autoimmune disease

Autoantibodies activate the TSH receptor
Causes multinodular goiter
Stimulates thyroid hormone synthesis, secretion and thyroid growth (goiter formation)

55
Q

A treatment for hyperthyroidism is antithyroid drugs, what are examples and what do they do?

A

Examples are methimazole and propulthiouracil (PTU)

Inhibit iodination of thyroglubulin and conversion of T4 to T3

56
Q

A treatment for hyperthyroidism is beta blockers. what beta blocker is used and how does it treat hyperthyroidism?

A

Propranolol has two roles:

L-isomer causes beta blockade, treats tachycardia, tremor, palpitations, anxiety, and heat intolerance

D-isomer inhibits the conversion of T4 to T3

57
Q

Radioactive iodine is a treatment for hyperthydroid, what does it do?

A

One time dose in pill form, results in destruction of thyroid tissue
DEFINITIVE THERAPY

58
Q

Partial or total thyroidectomy can be used but not often without S/S of cancer, why?

A

Not used extensively in absence of cancer as meds are effective and risk of removing parathyroids or recurrent laryngeal nerve
DEFINITIVE THERAPY

59
Q

When does thyroid storm happen?

A

6-18 hours post

60
Q

S/S of thyroid storm

A

hyperthermia, tachycardia, dysrhythmias, CHF, shock

61
Q

Causes of thyroid storm

A

Surgery, infection, trauma, toxemia, DKA

62
Q

During thyroid storm, treatment for
hyperthyroid -
hyperthermia -
hydration -

A

hyperthyroid - Sodium iodide, inderal/labetalol, Cortisol (increased utilization of cortisol), PTU

hyperthermia - acetaminophen, cooling blankets

hydration - Fluids and glucose (increased metabolism)

63
Q

sodium iodide and propranolol lead to euthyroid state in how many days

A

about 10

64
Q

Antithyroid drugs ___ weeks before surgery include sodium iodide and propylthiouracil

A

6-8

65
Q

In emergency surgery for hyperthyroid ism, what meds should you admin

A

sodium iodide, CORTISOL, and PTU

66
Q

How does cortisol work?

A

blocks peripheral conversion of T4 to T3, making rT3 instead

67
Q

What meds/gasses should you avoid during hyperthyroidism

A

halothane and atropine

68
Q

How/why do goiters occur

A

Results from chronic stimulation by TSH

Can occur in iodine deficiency states

69
Q

during a thyroidectomy there will be near monitoring, what tube do you use

A

nim tube or “Dragonfly monitor”

NIM - neural integrity monitoring. Used during head and neck procedure when laryngeal nerves could be injured

70
Q

***how can you tell RLN damage
unilateral -
bilateral -

A

unilateral - hoarseness

bilateral - Aphonia, stridor, aspiration

71
Q

***how can you tell SLN damage

A

Abnormal voice in upper registers

72
Q

after a thyroidectomy, how do you treat a hematoma?

A

Airway emergency requiring decompression and rapid intubation before airway compromise

73
Q

Why does hypocalcemia occur after thyroidectomy?

A

Due to inadvertent removal of parathyroids glands
Weakness, tetany, laryngospasm 24-72 hrs later
Can end with cardiovascular collapse

74
Q

Why does tracheomalacia occurs S/P thyroidectomy

A

tracheal softening, airway collapse with inspiration after removal of ETT

Endocrine - Troutmanm (7 decks)

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