Disorders Of The Thyroid

Question 1

Describe the normal thyroid

Answer 1

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

Question 2

How heavy is the thyroid normally

Answer 2

30-40 grams

Question 3

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

Answer 3

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

Question 4

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

Answer 4

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

Question 5

What do the parafollicular/ c cells do

Answer 5

Secrete calcitonin

Question 6

What are between the follicles

Answer 6

Parafollicular cells

Question 7

What does calcitonin do

Answer 7

Inhibits bone resorption and lowers plasma calcium levels

Question 8

What do thyroid cells look like in Graves’ disease

Answer 8

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

Question 9

What do thyroid cells look like in Hashimotos disease

Answer 9

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

Question 10

What are hurthle cells and what disease are they in

Answer 10

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

Question 11

what does the apex of the thyroid contain?

Answer 11

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

Question 12

what does the cytoplasm of the thyroid contain

Answer 12

nucleus, mitochondria, rough ER and ribosomes

Question 13

3 functions of the thyroid follicular cells?

Answer 13

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

Question 14

what happens when iodine is injected in food?

Answer 14

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

Question 15

iodide trapping/iodide pump?

Answer 15

follicular cells transport iodide from circulation to colloid

Question 16

how much iodide enters thyroid during normal synthesis

Answer 16

120 g/d

Question 17

how much iodide is secreted in T3 and T4?

Answer 17

80 g/d

Question 18

where does extra iodide in the thyroid go?

Answer 18

EC fluid and urine

Question 19

minimum daily intake of iodine for adults?

Answer 19

150 grams

Question 20

avg daily iodine intake for adults in US?

Answer 20

500 grams

Question 21

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

Answer 21

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

Question 22

what do 2 di-iodotyrosine molecules form?

Answer 22

thyroxin (T4)

Question 23

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

Answer 23

tri-iodotyrosine (T3)

Question 24

how are T3 and T4 transported?

Answer 24

plasma proteins

Question 25

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

Answer 25

thyroxine binding globulin (TBG)

Question 26

what do T3 and T4 plasma proteins do?

Answer 26

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

Question 27

what is hormonal output by the thyroid regulated by?

Answer 27

TSH and TRH

Question 28

what is TSH made by

Answer 28

anterior pituitary

Question 29

what is TRH made by

Answer 29

hypothalamis

Question 30

what is TSH secretion inhibited by

Answer 30

stress, dopamine, and somatostatin

Question 31

what is thyroid secretion inhibited and increased by in infants

Answer 31

Increased: cold Inhibited: warmth

Question 32

half life of TSH?

Answer 32

60 min

Question 33

what happens in chronic TSH secretion?

Answer 33

whole gland hypertrophies and becomes a goiter

Question 34

goiter?

Answer 34

abnormal enlargement of thyroid gland

Question 35

MCC goiter worldwide?

Answer 35

lack of iodine

Question 36

MCC goiter in US?

Answer 36

over/underproduction of thyroid hormones or nodules in the gland

Question 37

what do T3, T4, epinephrine, and norepinephrine do

Answer 37

inc. metabolic rate and stimulate NS and heart

Question 38

what induces the production of beta adrenergic receptors? why?

Answer 38

T3 to regulate transcription factors

Question 39

primary thyroid dysfunction?

Answer 39

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

Question 40

secondary thyroid dysfunction?

Answer 40

changes in pituitary TSH production

Question 41

primary diseases of thyroid?

Answer 41

hyper/hypothyroidism, thyrotoxicosis, graves disease, thyrotoxic crisis

Question 42

what is MC thyroid hormone overproduction due to

Answer 42

graves disease

Question 43

what is graves disease mediated by?

Answer 43

TSH receptor autoantibody

Question 44

what is TSH receptor autoantibody

Answer 44

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

Question 45

what is graves disease

Answer 45

symmectrical enlargement of thyroid and inc. vascularity

Question 46

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

Answer 46

TSH-R Ab

Question 47

what was TSH-R Ab formerly called

Answer 47

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

Question 48

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

Answer 48

if they'll relapse... NOT disease severity

Question 49

etiology of graves disease?

Answer 49

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

Question 50

possible mechanisms of graves?

Answer 50

defect or suppressor in T lymphocytes and molecular mimicry

Question 51

transient hyperthyroidism caused by?

Answer 51

release of excess thyroid hormones from necrotic thyroid tissue

Question 52

what preceds the development of hypothyroidism

Answer 52

hyperthyroidism

Question 53

MMC hypothyroidism?

Answer 53

hashimotos thyroiditis

Question 54

is hashimotos thyroiditis autoimmune

Answer 54

yes

Question 55

other causes of hypothyroidism besides hashimotos thyroiditis?

Answer 55

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

Question 56

what is a preventable cause of mental retardation

Answer 56

congenital hypothyroidism

Question 57

is hypothyroidism usually sporadic or hereditary

Answer 57

85% sporadic | 15% hereditary

Question 58

MC probs causing hereditary congenital hypothyroidism

Answer 58

inborn errors of T4 synthesis

Question 59

what is hypothyroidism characterized by

Answer 59

abnormally low serum T3 and T4

Question 60

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

Answer 60

free T4 is low and TSH is high

Question 61

most sensitive test for early hypothyroidism?

Answer 61

serum TSH

Question 62

what does the thyroid gland look like in hashimotos thyroiditis?

Answer 62

enlarged, rubbery, firm, nodular

Question 63

what happens to the thyroid gland as hashimotos thyroiditis progresses?

Answer 63

becomes smaller

Question 64

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

Answer 64

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

Question 65

pathogensis of hashimotos thyroiditis?

Answer 65

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

Question 66

the autoantibodies formed in hashimotos thyroiditis react with what antigens?

Answer 66

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

Question 67

what are high antibody titers of the thyroid diagnostic of?

Answer 67

hashimoto's thyroiditis

Question 68

what are moderate antibody titers of the thyroid seen in?

Answer 68

graves disease, multinodular goiter, thyroid neoplasm

Question 69

where are low titer levels of thyroid in?

Answer 69

elderly

Question 70

what is myxedema in (eye and facial puffiness)?

Answer 70

hypothyroidism