Thyroid Gland

Question 1

what do follicular cells enclose

Answer 1

colloid

Question 2

what does colloid contain

Answer 2

tyrosine containing thyroglobulin filled spheres

Question 3

what do parafollicular C cells secrete

Answer 3

calcitonin

Question 4

what is the main fuel for the thyroid gland

Answer 4

iodine

Question 5

describe the synthesis and stoage of T3 and T4

Answer 5

iodine taken up by follicle cells
iodine attaches to tyrosine residues on thyroglobulin to form MIT and DIT
coupling of MIT + DIT = T3
coupling of DIT and DIT = T4

Question 6

what is T4

Answer 6

thyroxine
accounts for 90%
converted to T3 by liver and kidney

Question 7

what is T3

Answer 7

triiodothyronine
accounts for 10%
4x more potent
major biologically active hormone

Question 8

properties of T3 and T4

Answer 8

hydrophobic and lipophilic so bind to plasma proteins

Question 9

which plasma proteins do T3/T4 bind to

Answer 9

thyroxine binding globulin
thyroxine binding prealbumin
albumin

Question 10

which form is biologically active - bound or unbound?

Answer 10

unbound

Question 11

what is measured in hopsitals?

Answer 11

free T3/T4

Question 12

states of increased TBG (increase total T4 but not fT4)

Answer 12

pregnancy, newborn 
OCP, tamoxifen, clofibrate, heroin 
Hep A 
biliary cirrhosis 
acute intermittent porphyria

Question 13

states of decreased TBG (decrease total T4 but not fT4)

Answer 13

androgens 
cushings 
acromegaly 
systemic illness 
chronic liver disease 
nephrotic syndrome 
phenytoin, carbamzepine

Question 14

metabolic effects of thyroid hormones

Answer 14

increase BMR and thermogenesis
increase blood glucose
mobilise fats from adipose tissue and increase fatty acid oxidation
increase protein synthesis

Question 15

symptoms of hypothyroidism

Answer 15

slow pulse 
fatigue 
cold intolerance 
tendency to put on weight easily 
myxoedema 
cretinism in babies
doughy skin 
periorbital puffiness
coarse, sparse hair 
constipation
hoarse voice
carpal tunnel 
menorrhagia

Question 16

symptoms of hyperthyroidism

Answer 16

fast pulse 
nervousness 
insomnia 
sweating 
heat intolerance 
tendency to lose weight easily 
palpitations 
tremor 
loose bowels 
eye symptoms 
brittle hair

Question 17

most common thyroid cancer

Answer 17

papillary

Question 18

worst prognosis thyroid cancer

Answer 18

anaplastic

Question 19

types of differentiated thyroid cancer

Answer 19

papillary

follicular

Question 20

features of differentiated tumours

Answer 20

take up iodine
secrete thyroglobulin
TSH driven
good prognosis

Question 21

approximately how many present with mets in differentiated tumours

Answer 21

5%

Question 22

spread of papillary

Answer 22

lymphatic

Question 23

associations of papillary

Answer 23

Hashimoto’s thyroiditis

Question 24

10yr mortality papillary

Answer 24

less than 5%

Question 25

second most common thyroid cancer

Answer 25

follicular

Question 26

spread of follicular

Answer 26

haematogenous

Question 27

investigation of thyroid cancer

Answer 27

US guided FNA | excision for biopsy

Question 28

gold standard treatment for thyroid cancer

Answer 28

surgery - lobectomy - subtotal or total thyroidectomy

Question 29

AMES risk stratification

Answer 29

Age Metastases Extent of primary tumour Size of primary tumour

Question 30

what is it important to monitor post-operatively

Answer 30

calcium

Question 31

what can be used as a tumour marker of recurrence in patients who have had surgery to remove a tumour

Answer 31

thyroglobulin

Question 32

what is the most common cause of hypo or hyper thyroidism

Answer 32

autoimmune disease

Question 33

hormone levels in hyperthyroid

Answer 33

low TSH | high fT3/4

Question 34

hormone levels in hypothyroid

Answer 34

high TSH | low fT3/4

Question 35

most common cause of goitrous hypothyroidism

Answer 35

Hashimoto's thyroiditis

Question 36

antibodies in Hashimoto's

Answer 36

``` thyroid peroxidase (TPO) occasionally anti-thyroglobulin ```

Question 37

what is seen on microscopy in Hashimotos

Answer 37

T cell infiltrate and inflammation

Question 38

other primary causes of hypothyroidism

Answer 38

``` maternally transmitted iodine deficiency drug induced post-radiation/ablation subacute thyroiditis postpartum thyroiditis ```

Question 39

causes of secondary hypothyroidism

Answer 39

hypothalamic - congenital, infection, infiltration, malignancy pituitary - panhypopituitarism, TSH deficiency

Question 40

management of hypo

Answer 40

thyroxine 50-100micrograms | in elderly with IHD, start at 25-50

Question 41

when is TSH an index of therapeutic success?

Answer 41

primary hypothyroidism | of no use in secondary

Question 42

what is myxoedema coma

Answer 42

severe hypothyroidism - typically affects old women with long standing hypothyroidism

Question 43

signs of myxoedema coma

Answer 43

ECG - bradycardia, low voltage complexes, heart block, T wave inversion, QT prolongation Type 2 resp failure adrenal failure

Question 44

treatment of myxoedema coma

Answer 44

``` ABCDE passively rewarm cardiac monitoring monitor vitals broad spectrum ABx ```

Question 45

causes of hyperthyroid

Answer 45

``` Graves multi-nodular goitre toxic nodule subacute thyroiditis post partum amiodarone, thyroxine and lithium treatment kelp supplements ```

Question 46

antibodies in Graves

Answer 46

TSH receptor antibodies

Question 47

eye disease in graves

Answer 47

``` lid retraction lid lag chemosis proptosis visual loss diplopia exophthalmos ```

Question 48

features of nodular thyroid disease

Answer 48

older patients with insidious onset feels nodular asymmetrical goitre high uptake on scintigraphy

Question 49

features of graves goitre

Answer 49

smooth symmetricl goitre high scintigraphy uptake see on US

Question 50

what is thyroid storm

Answer 50

medical emergency severe hyperthyroidism with resp and cardiac collapse hyperthermia and exaggerated reflexes

Question 51

Treatment of thyroid storm

Answer 51

``` Lugols iodine (potassium iodide) glucocorticoids PTU B Blockers fluids monitoring ```

Question 52

medication for hyperthyroidism

Answer 52

carbimazole PTU (preferred in pregnancy) radio-iodine

Question 53

side effects of carbimazole you do not want to miss

Answer 53

agranulocytosis

Question 54

medication for symptomatic relief

Answer 54

beta blockers - propanolol | these are sympathomimetic

Question 55

precautions with radio-iodine

Answer 55

no close contact for days after no pregnancy for 6m after high risk of hypothyroidism

Question 56

risks of surgery

Answer 56

scar, general risks recurrent laryngeal nerve palsy hypothyroidism/hypoparathyroidism

Question 57

what is DeQuervains thyroiditis

Answer 57

subacute viral associated with sore throat/fever usually self-limiting

Question 58

subclinical thyroid disease results

Answer 58

mildly overactive - TSH low, T3/4 normal | mildly failing - TSH high and T3/4 normal

Question 59

shin rash seen in Graves disease

Answer 59

pretibial myxoedema

Question 60

HLA haplotypes for hypothyroidism

Answer 60

DR3/DR5

Question 61

gene mutations in Hashimotos

Answer 61

CTLA-4 (negative regulator of T cell responses) | PTPN-22 (inhibitor of T cell function)

Question 62

hashimotos associated with higher risk of what

Answer 62

B cell lymphoma

Question 63

features of thyroid adenoma

Answer 63

discrete solitary mass | encapsulated by collagen cuff

Question 64

nodule in papillary carcinoma

Answer 64

usually solitary, can be multifocal | often cystic and may be calcified (psammoma bodies)

Question 65

features of anaplastic thyroid cancer

Answer 65

undifferentiated and aggressive | rapid growth

Question 66

features of medullary thyroid cancer

Answer 66

associated with MEN 2 rare derived from C cells (neuroendocrine) and so can secrete calcitonin composed of spindle or polygonal cells arranged in nests, trabeculae or follicles

Question 67

which type of cancer is associated with amyloid deposition

Answer 67

medullary

Question 68

treatment of medullary

Answer 68

total thyroidectomy

Question 69

Thy1

Answer 69

insufficient/uninterpretable

Question 70

Thy2

Answer 70

benign

Question 71

Thy3

Answer 71

atypia probably benign

Question 72

Thy4

Answer 72

atypia suspicious of malignancy

Question 73

Thy5

Answer 73

malignancy