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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
risks of surgery in hyperthyroidism
levothyroxine for life risk of - - recurrent laryngeal nerve palsy - hypothyroidism - hypoparathyroidism
26
management of thyrotoxic crisis
admit, ABCDE, monitor, treat as hyperthyroidism may require fluid resus, anti-arrthymic medication + beta blockers
27
what is Graves disease?
where TSH receptor antibodies cause primary hyperthyroidism most common cause of hyperthyroidism autoimmune condition 10F:1M 30-40yrs
28
pathophysio of Graves disease
TSH receptor antibodies mimic TSH and stimulate TSH receptors on thyroid (TSH receptor antibodies cause primary hyperthyroidism)
29
presentation of Graves (triad)
diffuse goitre - without nodules exophthalmos = bulging of eye out of socket pretibial myxodema = deposits of mucin under skin on shins
30
Graves disease investigations
low TSH high T3/4 TSH receptor antibody positive scintigraphy = high uptake hypercalcaemia + high alaline phosphatase - Graves associated with osteoporosis
31
treatment of Graves disease
carbimazole - usually normal thyroid function after 4-8weeks - block + replace quicker radioiodine = 1st choice for relapsed Graves !! smoking cessation
32
Graves complications associated with pregnancy
infertility / ammenorhoea spontaneous miscarriage still birth thyroid crisis in labour transient neonatal thyrotoxicosis (in baby) - caused by TRAb antibodies crossing placenta
33
how to distinguish between hypermesis + hyperthyroidism?
should improve by 20weeks gestation not TRAb positive only treat if persists >20weeks
34
gestational hCG-associated thryrotoxicosis
hCG increases T4 levels hCG causes hypermesis (N+V during pregnancy) should improve by 20weeks gestation
35
management of gestational hCG-associated thyrotoxicosis
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
consequences of giving carbimazole during 1st trimester
embryopathy (when organogenesis occuring) 2nd/3rd trimester only
37
scintigraphy uptake in thyroiditis
low
38
causes of thyroiditis
``` hashimoto's - hypo de quervain's - hyper post-partum drug-induced - amiodarone, lithium radiation infection ```
39
sub-acute thyroiditis
females, 20-50yrs may be triggered by viral infection - fever, neck tenderness scintigraphy = low uptake usually self-limiting (over months)
40
Hashimoto's thyroiditis
gradual autoimmune destruction of thyroid tissue commenest cause of hypothyroidism in DEVELOPED may be preceded by transient hyperfunction (hashitoxicosis)
41
hashimoto's thyroiditis presentation
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
hashimoto's thyroiditis associated antibodies
antithyroid peroxidase (anti-TPO) antithyroglobulin
43
hashimoto's pathyophysio
CD8 T cells mediate destruction of thyroid epithelium cytokine mediated cell death - recruited macrophages that may damage thyroid follicles
44
which carcinoma does hashimoto's thyroiditis particularly increase the risk of?
B cell NHL (non-Hodgkin lymphoma) in thyroid gland
45
De Quervains thyroiditis
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
post partum thyroiditis
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
post partum thyroiditis has increased incidence in what other condition?
type 1 diabetes --> post partum thyroiditis occurs in 25%
48
sick euthyroid syndrome
low TSH + T4 hospital inpatients, changes reversible upon recovery of systemic illness diagnosis = exclusion of hypothyroid no treatment
49
what does a high TSH and low free T4 suggest?
subclinical hypothyroidism - on their way to developing hypothyroidism, TSH is more sensitive and early marker of thyroid problems
50
most common malignant tumour of the thyroid
papillary (75-85%) follicular (10-20) medullary anaplastic
51
which tumour variants come under the phrase differentiated thyroid cancer (DTC)?
papillary + follicular variants "differentiated" features = good prognosis most take up iodine + secrete thyroglobulin lower incidence in afro-americans more common in women
52
environmental causes of differentiated thyroid cancers
ionisng radiation - papillary carcinoma iodine deficiency - follicular carcinoma
53
which thyroid tumour can secrete calcitonin?
medullary thyroid carcinoma calcitonin can be used as a tumour marker
54
histology of medullary thyroid carcinoma
derived from C-Cells (parafollicular) derived from neural crest, not thyroid tissue
55
types of medullary thyroid carcinoma
sporadic (70%) - solitary nodule familial - bilateral/multicenteric associated with multiple endocrine neoplasia (MEN) - very young patients, prophylactic thyroidectomy
56
investigations + treatment of medullary thyroid carcinoma
neck USS + FNA basal serum calcitonin + CEA treatment = total thyroidectomy --> recurrence in 35%
57
thyroid lymphoma
females 70-80 rapid onset of mass in thyroid rare, associated with hashimoto's ``` diagnosis = biopsy Mx = steroid, chemo, radio ```
58
anaplastic carcinoma of the thyroid
undifferentiated + agressive tumours rapid growth + involvement of neck structures poor prognosis elderly females
59
mutation strongly associated with anaplastic carcinoma
TP53
60
histology of papillary carcinoma
papillary projections + pale empty nuclei
61
histology of follicular carcinoma
microscopically capsular invasion
62
lymph node + haematogenous spead in papillary carcinoma?
lymph node metastisis haematogenous spread = uncommon
63
lymph node + haematogenous spead in follicular carcinoma?
rarely lymphatic spread haematogenous spread = bone, lung, liver
64
differences between papillary + follicular carcinoma
both = slow grow, good prognosis papillary - lymphatic spread - young women follicular - spread to lung, liver + bones - middle aged women
65
management of differentiated thyroid cancer
total thyroidectomy radioiodine to kill residual cells yearly thyroglobulin to detect early recurrent disease suppress TSH potential lobectomy in low risk group
66
what can be used as a tumour cell marker for differentiated thyroid cancer?
thyroglobulin (Tg)
67
follow up management of differentiated thyroid cancer
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
what is thyroglobulin?
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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