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Pathophysiology > Disorders Of The Thyroid > Flashcards

Disorders Of The Thyroid Flashcards

1
Q

Describe the normal thyroid

A

Firm, red/brown, smooth, 2 lateral lobes connected by isthmus

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2
Q

How heavy is the thyroid normally

A

30-40 grams

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3
Q

What do cells of the thyroid look like when it is inactive

A

Follicles are large, lining of cells are flat, colloid is abundant

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4
Q

What do cells of the thyroid look like when it is active

A

Follicles are small, lining Cells are cuboidal or calendar, colloid is scant, edges are scalloped

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5
Q

What do the parafollicular/ c cells do

A

Secrete calcitonin

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6
Q

What are between the follicles

A

Parafollicular cells

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7
Q

What does calcitonin do

A

Inhibits bone resorption and lowers plasma calcium levels

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8
Q

What do thyroid cells look like in Graves’ disease

A

Scant colloid with scalloped edges, follicular epithelial cells are tall/columnar and inc. in size/number, small and closely packed follicles, scattered lymphocytes

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9
Q

What do thyroid cells look like in Hashimotos disease

A

Lymphocytes and plasma cells, scattered follicles with eosinophilia cytoplasm, follicles are destroyed, and fibrosis

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10
Q

What are hurthle cells and what disease are they in

A

thyroid follicular epithelial cells that are large with abundant pink cytoplasm; hashimotos diseases

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11
Q

what does the apex of the thyroid contain?

A

golgi with small secretory granules that have thyroglobulin, lysosomes, nad phagosomes

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12
Q

what does the cytoplasm of the thyroid contain

A

nucleus, mitochondria, rough ER and ribosomes

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13
Q

3 functions of the thyroid follicular cells?

A
  1. collect and transport iodine to colloid
  2. make thyroglobulin and secrete it to colloid
  3. release thyroid hormones
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14
Q

what happens when iodine is injected in food?

A

it’s converted to iodide which is taken up by the thyroid, follicular cells transport iodide from circulation to colloid

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15
Q

iodide trapping/iodide pump?

A

follicular cells transport iodide from circulation to colloid

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16
Q

how much iodide enters thyroid during normal synthesis

A

120 g/d

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17
Q

how much iodide is secreted in T3 and T4?

A

80 g/d

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18
Q

where does extra iodide in the thyroid go?

A

EC fluid and urine

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19
Q

minimum daily intake of iodine for adults?

A

150 grams

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20
Q

avg daily iodine intake for adults in US?

A

500 grams

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21
Q

where are T3 and T4 made in the thyroid? what process occurs?

A

colloid by process of iodination and coupling of tyrosine molecules bound together by thyroglobulin

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22
Q

what do 2 di-iodotyrosine molecules form?

A

thyroxin (T4)

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23
Q

what do 1 mono-iodotyrosine molecules and 2 di-iodotyrosine molecules form?

A

tri-iodotyrosine (T3)

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24
Q

how are T3 and T4 transported?

A

plasma proteins

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25
Q

what is the main plasma protein carrier for T3 and T4?

A

thyroxine binding globulin (TBG)

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26
Q

what do T3 and T4 plasma proteins do?

A

transport T3 and T4 into the serum and facilitate uniform distribution of hormones within tissues

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27
Q

what is hormonal output by the thyroid regulated by?

A

TSH and TRH

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28
Q

what is TSH made by

A

anterior pituitary

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29
Q

what is TRH made by

A

hypothalamis

30
Q

what is TSH secretion inhibited by

A

stress, dopamine, and somatostatin

31
Q

what is thyroid secretion inhibited and increased by in infants

A

Increased: cold
Inhibited: warmth

32
Q

half life of TSH?

A

60 min

33
Q

what happens in chronic TSH secretion?

A

whole gland hypertrophies and becomes a goiter

34
Q

goiter?

A

abnormal enlargement of thyroid gland

35
Q

MCC goiter worldwide?

A

lack of iodine

36
Q

MCC goiter in US?

A

over/underproduction of thyroid hormones or nodules in the gland

37
Q

what do T3, T4, epinephrine, and norepinephrine do

A

inc. metabolic rate and stimulate NS and heart

38
Q

what induces the production of beta adrenergic receptors? why?

A

T3 to regulate transcription factors

39
Q

primary thyroid dysfunction?

A

dysfunction or disease of thyroid gland itself so theres a defect in TH production

40
Q

secondary thyroid dysfunction?

A

changes in pituitary TSH production

41
Q

primary diseases of thyroid?

A

hyper/hypothyroidism, thyrotoxicosis, graves disease, thyrotoxic crisis

42
Q

what is MC thyroid hormone overproduction due to

A

graves disease

43
Q

what is graves disease mediated by?

A

TSH receptor autoantibody

44
Q

what is TSH receptor autoantibody

A

agonist that stimulates thyroid follicular cells to make too much T3 and T4

45
Q

what is graves disease

A

symmectrical enlargement of thyroid and inc. vascularity

46
Q

serum of 90% of patients with graves disease contain what?

A

TSH-R Ab

47
Q

what was TSH-R Ab formerly called

A

long acting thyroid stimulator (LATS) or thyroid stimulating immuloglobulin (TSI)

48
Q

TSH-R Ab serum levels in ppl with graves indicate what?

A

if they’ll relapse… NOT disease severity

49
Q

etiology of graves disease?

A

unknown; maybe familial/genetic, higher rates in monozygotic twins, certain antigens have this more

50
Q

possible mechanisms of graves?

A

defect or suppressor in T lymphocytes and molecular mimicry

51
Q

transient hyperthyroidism caused by?

A

release of excess thyroid hormones from necrotic thyroid tissue

52
Q

what preceds the development of hypothyroidism

A

hyperthyroidism

53
Q

MMC hypothyroidism?

A

hashimotos thyroiditis

54
Q

is hashimotos thyroiditis autoimmune

A

yes

55
Q

other causes of hypothyroidism besides hashimotos thyroiditis?

A

lymphocytic thyroiditis after hyperthyroidism, ablation, disease of hypothalamus or pituitary, drugs, congenital

56
Q

what is a preventable cause of mental retardation

A

congenital hypothyroidism

57
Q

is hypothyroidism usually sporadic or hereditary

A

85% sporadic

15% hereditary

58
Q

MC probs causing hereditary congenital hypothyroidism

A

inborn errors of T4 synthesis

59
Q

what is hypothyroidism characterized by

A

abnormally low serum T3 and T4

60
Q

what are free T4 levels like in hypothyroidism? TSH levels?

A

free T4 is low and TSH is high

61
Q

most sensitive test for early hypothyroidism?

A

serum TSH

62
Q

what does the thyroid gland look like in hashimotos thyroiditis?

A

enlarged, rubbery, firm, nodular

63
Q

what happens to the thyroid gland as hashimotos thyroiditis progresses?

A

becomes smaller

64
Q

tell me about the thyroid in the late stages of hashimotos thyroiditis?

A

gland is atrophic, fibrotic, and weighs 10-20 grams

65
Q

pathogensis of hashimotos thyroiditis?

A

unclear; possible defect in suppressor T lymphocytes, autoantibodies formed, or cytokine release and inflammation that cause glandular destruction

66
Q

the autoantibodies formed in hashimotos thyroiditis react with what antigens?

A

thyroglobulin antibody, thyrodiol peroxidase antibody, and TSH receptor blocking antibody

67
Q

what are high antibody titers of the thyroid diagnostic of?

A

hashimoto’s thyroiditis

68
Q

what are moderate antibody titers of the thyroid seen in?

A

graves disease, multinodular goiter, thyroid neoplasm

69
Q

where are low titer levels of thyroid in?

A

elderly

70
Q

what is myxedema in (eye and facial puffiness)?

A

hypothyroidism

Pathophysiology (17 decks)

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