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Thyroid Flashcards

0
Q

where is the thyroid located?

A

anteriorinferior neck at level of thyroid cartliage

rt and lt lobe

joined by isthmus

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1
Q

What is the function of the thyroid?

A

synthesiszes, stores and secretes hormones through tissue/blood - not ducts

control BMR - basial metabolic rate

maintains metabolism growth and development

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2
Q

what is the third lobe of the thyroid that some people have?

A

pyramidal lobe - arises from isthmus

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3
Q

how does the thyroid interact with the trachea?

A

straddles trachea anteriorly

bounded laterally by carotid arteries and jugular veins

pyramidal lobe arises from isthmus

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4
Q

When does the thyroid develop prenatally?

A

in the third week

thyroglossal duct -connects thryoid to tongue and atrophies by 8th week - if it persists = cysts, fistulas, pyramidal lobe

ectopic tissue

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5
Q

What is the shape of the thyroid?

A

U or H shaped

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6
Q

Which lobe is larger rt or lt, male or female?

A

Right is larger

Females > males

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7
Q

what is the normal size of the thyroid?

A

4-6cm (L) x 1.3-1.8cm (AP) x 1.5-2cm (W)

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8
Q

What is the relational anatomy to the thyroid?

Review/learn slide 12

A

anterior: strap muscles (sternohyoid, omohyoid, sternothyroid)*

sternocleidomastoid muscle

posterolateral: CCA, IJV, *longus colli muscle

Medial: larynx, trachea, esophagus

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9
Q

What is the blood supply to the thyroid?

A

highly vascular

two superior thyroid arteries from ECA descend to upper poles

two inferior thyroid arteries from subclavian and ascend to lower poles

corresponding veins drain into IJV

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10
Q

What role does iodine play in they thyroid function?

A

processed by follicular cells to manufacture, store and secrete thyroid hormones

(the thyroid maintains body metabolism, growth and development)

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11
Q

What hormones does the thyroid produce?

A

T3 triiodothyronine

T4 thyroxine

when thyroid hormone is needed by the body it is released into the blood stream by action of thyrotropin or thyroid stimulating hormone (TSH), produced by the pituitary gland

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12
Q

What is calcitonin?

A

decreases concentration of calcium in blood by first acting on bone to inhibit its breakdown

helps maintain homeostasis of blood calcium

secreted by C-cells or parafollicular cells

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13
Q

Which thyroid hormone is most potent T3 or T4

A

T3 - 10% produced - most potent

T4 - 90% produced less potent

both stored in colloid

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14
Q

what does Euthyroid mean?

A

the correct amount of hormone production

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15
Q

What causes hypothyroidism?

A

undersecretion of hormones

low intake of iodine

inability of thyroid to produce thyroid hormone

chronic autoimmune thyroiditis

pituitary gland or hypothalamus diseases

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16
Q

What are the clinical signs of the hypothyroidism?

A

myxedema: nonpitting waxy edema of the skin on the face and shins

weight gain

hair loss

tissue around eyes

lethargy

intellectual and motor slowing

cold intolerance

constipation

hoarseness

dry skin

menstrual irregularities

decrease sweating

bradycardia

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17
Q

What is the sonographic appearance of hypothyroid?

A

diffusely abnormal

decreased heterogeneous echogenicty

normal

enlarged with irregular surface

small calcifications

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18
Q

What is hyperthyroidsim?

A

over-secretion of thyroid hormones

entire gland out of control

Graves’ disease

localized neoplasm causes overproduction of hormones:

trophoblastic tumors: hydatidiform mole, choriocarcinoma, some testicular tumors

toxic adenomas

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19
Q

what are the clinical symptoms of hyperthyroidism?

A

dramatic ^ in metabolic rate

weight loss despite ^ in appetite

nervous energy

tremor

excessive sweating

heat intolerance

tachycardia/palpitation

exophthalmos - bulging eyes and retraction of eyelids

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20
Q

what is the sonographic appearance of hyperthyroidism?

A

normal sized or enlarged gland

inhomogeneous

hypervascularity - key sign for Graves’ disease

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21
Q

What are the thyroid function tests?

A

nuclear medicine

blood tests to measure T3 and T4

US does not evaluate function

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22
Q

What is a “hot” nodule from a nuc med scan?

A

hyperfunctioning nodule

5-10% of all nodules - usually benign

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23
Q

What is a “cold” nodule from a nuc med scan?

A

non-functioning

80-85% of all nodules – 10-15% of these are malignant

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24
Q

What controls the secretion of TSH and what produces it?

A

controls: thyrotropin releasing hormone (TRH)

Produced: hypothalamus

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25
Q

What is the most common pathology of the thyroid?

A

iodine deficiency

26
Q

What does an iodine deficiency lead to?

A

goiter formation

hypothyroidism

27
Q

if its not iodine deficiency, what else can cause hypothyroidism and hyperthyroidism?

A

autoimmune disorders

28
Q

What is a goiter?

A

diffuse enlargement of thyroid

peak age 35-50 yrs old

females 3:1

hamper hormone secretion

may become very large

endemic goiter

29
Q

what percent of thyroid disease is caused by hyperplasia of the gland?

A

80%

30
Q

What are the different types of goiters?

A

nodular hyperplasia

multinodular goiter

adenomatous hyperplasia

simple/non-toxic

multinodular toxic

31
Q

what is multinodular/ toxic goiter?

A

may be spontaneous

may be end stage of simple goiter

enlarged heterogenous

slide 44 for image

focal scarring, ischemia, necrosis, cyst formation, calcifications

asymmetry

32
Q

What causes goiters?

A

iodine deficiency

thyroid hormone deficiency

grave’s disease

thyroiditis

neoplasm

cyst

33
Q

What is a non-toxic simple goiter?

A

diffuse uniform enlargement

iodine deficiency - gland unable to supply adequate hormones

dietary shortage or gland malfunction

may lag behind = hypothyroidism

often gland keeps up with demand and provides normal release of hormones

35
Q

What are the labs for grave’s disease?

A

increase T3 and T4

36
Q

What is thyroiditis?

A

swelling and tenderness

infection or autoimmune

two types: De Quervain’s (viral) Hashimoto’s (destructive autoimmune disorder)

37
Q

What is De Quervain’s (subacute granulomatous thyroiditis)?

A

fever

enlarged gland

pain on palpation

pain may radiate to ear or jaw

38
Q

what is Hashimoto’s (chronic autoimmune lymphocytic)?

see slide 52 for image

A

painless onset

diffusely enlarged gland

young to middle age females

heterogeneous as progresses and tenderness

eventual severe gland damage = hypothyroidism most common cause in adults

39
Q

How does Hashimoto’s appear sonographically?

A

hypoechoic, coarse and homogeneous

thickened fibrous strands - chronic sign

increased color flow - in acute stage

fibrotic, ill-defined and heterogeneous over time

increased risk for malignancy

40
Q

What are the benign lesions of the thyroid?

A

Palpable nodule - most common cause for US

Cysts - degeneration of follicular adenoma, may have debris

adenoma - neoplasm, complete fibrous encapsulation, more often females, may have appearance of peripheral halo, may cause hyperfunction

41
Q

What are cysts?

A

10-15% of solitary nodules

common - colloid or degeneration or necrosis of adenomatous nodules

benign if < 4 cm

42
Q

What is an adenomas?

A

true benign neoplasm

encapsulated

solitary

well - defined

females

MOST COMMON THYROID NEOPLASM

“COLD” nuc med nodule

43
Q

what are the different types of adenomas

A

embryonal

fetal

colloid

follicular

hyperplastic

44
Q

What is carcinoma of the thyroid?

A

malignant

rare

most common 40-60 yrs

risk of malignancy decreases with multiple nodules

variable in appearance

calcifications present 50-80% of all types non shadowing

females

especially suspicious single nodules and under 14 yrs old and over 65 yrs old

45
Q

What is papillary carcinoma?

A

most common form of malignant thyroid cancer

see slide 65 for image

3rd and 7th decades of life

females

predominant thyroid cancer in children

25% laminate calcifications

20% metastatic cervical adenopathy (check those lymph nodes!!)

least aggressive

hypoechoic

microcalcifications

hypervascularity

cervical lymph node metastasis

46
Q

what shape are healthy lymph nodes? suspicious?

A

oval/flat

round

47
Q

What is follicular carcinoma?

A

more aggressive than papillary

females

solid nodule

sonographically = irregular, firm, nodular enlargement

metastases to lung, bone and other distant sites

48
Q

What is medullary carcinoma?

A

5% of thyroid cancers

hard bulky mass, enlargement

sonographically = bright enchogenic foci within solid mass

associated with elevated serum calcitonin and multiple endocrine neoplasm (MEN) type II

49
Q

What is anaplastic carcinoma?

A

rare, <2%

occurs after age 50

most lethal

hard fixed mass with rapid growth

invades neck structures, causing death by compression and asphyxiation

6months - 1 year life expectancy

50
Q

what is lymphoma?

A

primarily Non-hodgkin’s type

older females

s

sonographically = nonvascular hypoechoic mass, adjacent thyroid heterogeneous

51
Q

what is the parathyroid anatomy?

A

four individual glands PAIRED together (2 at the top, 2 at the bottom)

2 posterior superior poles, 2 posterior inferior poles

may be in neck/mediastinum

flat and disc shaped

52
Q

Where is the location of the parathyroid?

A

medial and posterior to the thyroid gland (closest to the trachea)

53
Q

What are the sonographic findings of the parathyroid glands?

A

not usually seen, isochoic to thyroid

5mm enlarged, hypoechoic

enlongated masses between posterior longus colli and anterior thyroid*

54
Q

What is the parathyroid physiology?

A

calcium sensing organs

produce (PTH) parathyroid hormone

serum calcium decrease PTH^

PTH acts on bone, kidney and intestine to enhance calcium absorption

unexplain hypercalcemia = US

55
Q

what is primary hyperparathyroidism?

A

increased function of the parathyroid glands

females

^ PTH from an adenoma, hyperplasia or carcinoma

primary hyperplasia - hyperfunction without and apparent cause

56
Q

What is secondary hyperparathyroidism?

A

chronic hypocalcemia from renal failure, vitamin D deficiency or malabsorption syndromes

compensatory reaction

leads to PTH stimulation

includes all 4 glands

primary hyperplasia - parathyroid

57
Q

what is a parathyroid adenoma?

A

most common cause of primary hyperparathyroidism 80%

sonographically - hypoechoic, solid, encapsulated, discrete borders

cannot discern adenoma from cancer

58
Q

What is a thyroglossal duct cyst?

see slide 85 for image

A

congenital anomaly

midline and anterior to trachea

remnant of tubular development

sonographically: cystic mass anterior to trachea

oval or spherical masses rarely larger than 2 or 3 cm

59
Q

What is branchial cleft cysts?

A

remnant of embryologic development

tract from pharyngeal cavity to auricle

results in cystic formation lateral to thyroid gland

may present with solid components especially if infected

see slide 88 for image

60
Q

What is an ascess?

A

can be anywhere in the neck

wide range of appearances

most common - low level echogenicity and irregular walls

increased blood flow

check for air shadowing

61
Q

What is adenopathy?

A

shape of node should be oval

homogeneous with central core echo complex

more round ? malignant

has the patient been scratched any where
echo-free node ? inflammatory process

fine needle aspiration to confirm

62
Q

What does an abnormal lymph node look like?

A

loss of fatty hilum

irregular margins

cystic areas of degeneration

calcifications

round

> 7mm width or AP

65
Q

What is Grave’s disease?

A

female > 30

autoimmune

most frequent cause of hyperthyroidism

triad - diffuse toxic goiter, exopthalmos, dermis thickening

sonographically - hypoechoic, diffuse homogeneous enlargement, increase color flow

“thyroid inferno”because of the increased color flow on doppler

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