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endocrine > thyroid > Flashcards

thyroid Flashcards

1
Q

main cause of diffuse goitre

A

iodine deficiency

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2
Q

toxic multinodular goitre

A

where nodule develop on the thyroid gland that act independently of the normal feedback system + continously produce excessive thyroid hormone

2nd most common cause of thyrotoxicosis

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3
Q

toxic multinodular goitre presentation

A

most patients over 50
goitre with firm nodules
atrial fibrillation

patchy uptake on scintigraphy
high T3/T4
low TSH

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4
Q

toxic multinodular goitre treatment

A

radio-active iodine if significant hyperthyroid

surgery if structural problem or significant retrosternal extension

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5
Q

what are the 3 main embryological abnormalities associated with the thyroid?

A

failure to descend = lingual thyroid
excessive descent = retrosternal location in mediastinum

thyroglossal duct

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6
Q

how does the thyroid embryologically develop?

A

develops from evagination of pharyngeal epithelium

descent from foramen caecum to normal location

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7
Q

causes of hypothyroidism

A

hashimoto’s thyroiditis - commonest developed
iodine deficiency - commenest developing

medications - lithium + amiodarone

hypopituitarism = pituitary failing to produce enough TSH, caused by: tumours, infection, radiaation

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8
Q

incidence of hypothyroidism

A

higher in white populations

higher in areas of high iodine intake - too much inhibits

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9
Q

T3/4 + TSH levels in hyperthyroidism

A

TSH = low

t3/4 = high

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10
Q

T3/4 + TSH levels in primary hypothyroidism

A

TSH = high

T3/4 = low

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11
Q

T3/4 + TSH levels in secondary hypothyroidism

A

both LOW

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12
Q

hypothyroidism presentation

A 
weight gain
cold intolerance
fluid retention - oedema, pleural effusion
constipation
coarse hair/loss
psychosis, tendon jerks
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13
Q

management of hypothyroidism

A

levothyroxine

–> dose is titrated until TSH levels are normal - checked monthly until stable

if TSH is high - increase dose

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14
Q

myxoedema coma

A

severe hypothyroidism, medical emergency
women with long standing/untreated hypothyroidism
high mortality

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15
Q

presentation of myxoedema coma

A

bradycardia
heart block, T wave inversion
type 2 resp failure - hypoxia, resp acidosis
adrenal failure in some

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16
Q

hyperthyroidism presentation

A 
anxiety + irritability
sweating + heat intolerance
weight loss
fatigue
loose stool

eyelid retraction

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17
Q

post-partum thyroiditis

A

transient thyrotoxic spike then falls + become hypothyroid

  • course of about a year
  • hypothyroid stage associated with postnatal depression

don’t treat thyrotoxicosis stage - would exacerbate fall to hypothyroid stage

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18
Q

hyperthyroidism management

A

anti-thyroid drugs - carbimazole (first line), propylthiouracil

radioactive iodine
beta blockers (symptommatic relief)
surgery

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19
Q

whats the first line anti-thyroid drug in treatment of hyperthyroidism in your average patient?

A

carbimazole

once patient has normal thyroid hormone levels, maintenance either-
> titration-block = dose titrated to maintain normal levels
> block + replace = dose is sufficient to block all production, takes levothyroxine titrated to effect

complete remission + ability to stop taking is usually <18months

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20
Q

whats the first line anti-thyroid drug in treatment of hyperthyroidism in 1st trimester of pregnancy?

A

propylthiouracil

small risk of hepatic reactions - including death

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21
Q

side effects of anti-thyroid drugs

A

allergic reactions - rash, urticaria
cholestatic jaundice

agranulocytosis

  • highest risk in first 6 weeks
  • warn patients verbally + in writing
  • ATDs cannot be used again
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22
Q

radioactive iodine treatment in hyperthyroidism

A

single dose is taken up by thyroid gland + radiation destroys a proportion of thyroid cells (decreasing thyroid hormone production)

remission can take up to 6 months
patients can be left hypothyroid - levothyroxine for life

must not be pregnant within 6 months, avoid kids + pregnant for 3 weeks, limit contact with people for several days post dose

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23
Q

beta blockers in the treatment of hyperthyroidism

A 
propranolol - non-selectively blocks adrenergic activity (not just heart)
symptomatic relief only
useful in thyrotoxicosis crisis
block adrenalin related symtptoms
**not in asthma**
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24
Q

symptomatic relief of choice in hyperthyroidism

A

propranolol

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25
Q

risks of surgery in hyperthyroidism

A

levothyroxine for life

risk of -

  • recurrent laryngeal nerve palsy
  • hypothyroidism
  • hypoparathyroidism
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26
Q

management of thyrotoxic crisis

A

admit, ABCDE, monitor, treat as hyperthyroidism

may require fluid resus, anti-arrthymic medication + beta blockers

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27
Q

what is Graves disease?

A

where TSH receptor antibodies cause primary hyperthyroidism
most common cause of hyperthyroidism
autoimmune condition

10F:1M
30-40yrs

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28
Q

pathophysio of Graves disease

A

TSH receptor antibodies mimic TSH and stimulate TSH receptors on thyroid

(TSH receptor antibodies cause primary hyperthyroidism)

29
Q

presentation of Graves (triad)

A

diffuse goitre - without nodules

exophthalmos = bulging of eye out of socket

pretibial myxodema = deposits of mucin under skin on shins

30
Q

Graves disease investigations

A

low TSH
high T3/4

TSH receptor antibody positive
scintigraphy = high uptake

hypercalcaemia + high alaline phosphatase - Graves associated with osteoporosis

31
Q

treatment of Graves disease

A

carbimazole

  • usually normal thyroid function after 4-8weeks
  • block + replace quicker

radioiodine = 1st choice for relapsed Graves

!! smoking cessation

32
Q

Graves complications associated with pregnancy

A

infertility / ammenorhoea
spontaneous miscarriage
still birth
thyroid crisis in labour

transient neonatal thyrotoxicosis (in baby) - caused by TRAb antibodies crossing placenta

33
Q

how to distinguish between hypermesis + hyperthyroidism?

A

should improve by 20weeks gestation
not TRAb positive

only treat if persists >20weeks

34
Q

gestational hCG-associated thryrotoxicosis

A

hCG increases T4 levels
hCG causes hypermesis (N+V during pregnancy)

should improve by 20weeks gestation

35
Q

management of gestational hCG-associated thyrotoxicosis

A

supportive/symptomatic managment - beta blockers if needed

low dose antithyroid drugs - wait as late as possible (baby failing to thrive, weight loss)

1st trimester = propylthiouracil - risk of liver toxicity to mother
2nd/3rd trimester = carbimazole

36
Q

consequences of giving carbimazole during 1st trimester

A

embryopathy (when organogenesis occuring)

2nd/3rd trimester only

37
Q

scintigraphy uptake in thyroiditis

A

low

38
Q

causes of thyroiditis

A 
hashimoto's - hypo
de quervain's - hyper
post-partum
drug-induced - amiodarone, lithium
radiation
infection
39
Q

sub-acute thyroiditis

A

females, 20-50yrs
may be triggered by viral infection - fever, neck tenderness

scintigraphy = low uptake

usually self-limiting (over months)

40
Q

Hashimoto’s thyroiditis

A

gradual autoimmune destruction of thyroid tissue
commenest cause of hypothyroidism in DEVELOPED

may be preceded by transient hyperfunction (hashitoxicosis)

41
Q

hashimoto’s thyroiditis presentation

A

may be preceded by transient hyperfunction (hashitoxicosis)
middle aged women - 45/60yrs
other autoimmune
**associated with HLA-DR3 + -DR5
initially causes goitre followed by atrophy of gland
may see progressive fibrosis within gland

42
Q

hashimoto’s thyroiditis associated antibodies

A

antithyroid peroxidase (anti-TPO)

antithyroglobulin

43
Q

hashimoto’s pathyophysio

A

CD8 T cells mediate destruction of thyroid epithelium

cytokine mediated cell death - recruited macrophages that may damage thyroid follicles

44
Q

which carcinoma does hashimoto’s thyroiditis particularly increase the risk of?

A

B cell NHL (non-Hodgkin lymphoma) in thyroid gland

45
Q

De Quervains thyroiditis

A

viral infection with signs of hyperthyroidism

  • fever, neck pain, tenderness, dysphagia
  • self-limiting - NSAIDs, maybe beta-blockers

hyperthyroid phase followed by hypothyroid phase as TSH level falls - negative feedback

46
Q

post partum thyroiditis

A

transient thyrotoxic then falls + becomes hypothyroid - hypo stage assoc with postnatal depression
can persist up to a year

dont treat - would exacerbate fall to hypo stage
5% of all women + 25% of T1DM

47
Q

post partum thyroiditis has increased incidence in what other condition?

A

type 1 diabetes

–> post partum thyroiditis occurs in 25%

48
Q

sick euthyroid syndrome

A

low TSH + T4

hospital inpatients, changes reversible upon recovery of systemic illness
diagnosis = exclusion of hypothyroid
no treatment

49
Q

what does a high TSH and low free T4 suggest?

A

subclinical hypothyroidism

  • on their way to developing hypothyroidism, TSH is more sensitive and early marker of thyroid problems
50
Q

most common malignant tumour of the thyroid

A

papillary (75-85%)

follicular (10-20)
medullary
anaplastic

51
Q

which tumour variants come under the phrase differentiated thyroid cancer (DTC)?

A

papillary + follicular variants

“differentiated” features = good prognosis
most take up iodine + secrete thyroglobulin

lower incidence in afro-americans
more common in women

52
Q

environmental causes of differentiated thyroid cancers

A

ionisng radiation - papillary carcinoma

iodine deficiency - follicular carcinoma

53
Q

which thyroid tumour can secrete calcitonin?

A

medullary thyroid carcinoma

calcitonin can be used as a tumour marker

54
Q

histology of medullary thyroid carcinoma

A

derived from C-Cells (parafollicular)

derived from neural crest, not thyroid tissue

55
Q

types of medullary thyroid carcinoma

A

sporadic (70%) - solitary nodule

familial - bilateral/multicenteric

associated with multiple endocrine neoplasia (MEN) - very young patients, prophylactic thyroidectomy

56
Q

investigations + treatment of medullary thyroid carcinoma

A

neck USS + FNA
basal serum calcitonin + CEA

treatment = total thyroidectomy
–> recurrence in 35%

57
Q

thyroid lymphoma

A

females 70-80
rapid onset of mass in thyroid
rare, associated with hashimoto’s

diagnosis = biopsy
Mx = steroid, chemo, radio
58
Q

anaplastic carcinoma of the thyroid

A

undifferentiated + agressive tumours
rapid growth + involvement of neck structures

poor prognosis
elderly females

59
Q

mutation strongly associated with anaplastic carcinoma

A

TP53

60
Q

histology of papillary carcinoma

A

papillary projections + pale empty nuclei

61
Q

histology of follicular carcinoma

A

microscopically capsular invasion

62
Q

lymph node + haematogenous spead in papillary carcinoma?

A

lymph node metastisis

haematogenous spread = uncommon

63
Q

lymph node + haematogenous spead in follicular carcinoma?

A

rarely lymphatic spread

haematogenous spread = bone, lung, liver

64
Q

differences between papillary + follicular carcinoma

A

both = slow grow, good prognosis

papillary

  • lymphatic spread
  • young women

follicular

  • spread to lung, liver + bones
  • middle aged women
65
Q

management of differentiated thyroid cancer

A

total thyroidectomy
radioiodine to kill residual cells
yearly thyroglobulin to detect early recurrent disease
suppress TSH

potential lobectomy in low risk group

66
Q

what can be used as a tumour cell marker for differentiated thyroid cancer?

A

thyroglobulin (Tg)

67
Q

follow up management of differentiated thyroid cancer

A

TSH + Tg every 6 months for first 5yrs then annually for next 5yrs - consider discharge after this

TSH lower level than normal (0.4-4)
thyroglubulin (Tg) levels - tumour cell marker

68
Q

what is thyroglobulin?

A

protein precursor of T4/T3
made by thyroid follicular epithelium

can be used as a tumour cell marker for differentiated thyroid cancer

endocrine (15 decks)

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