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Endocrine > endocrine disease-thyroid > Flashcards

endocrine disease-thyroid Flashcards

1
Q

histological features of multinodular goitre 5

A 
cystically dilated follicles 
cholesterol clefts
variably sized follicles
fibrous septae
foamy macrophages
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2
Q

histological features of grave’s disease

A

papillary architecture

cells have a more columnar appearance

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3
Q

histological features of hashimotos thyroiditis

A

lymphoid aggregates with germinal centre formation
small lymphocytes
oncocytic epithelial cells

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4
Q

histological features of follicular adenoma

A

-encapsualted lesion
-made up of thyroid follicles
-clonal population but benign
if capsular or vascular invasion then becomes follicular carcinoma

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5
Q

histological features of follicular carcinoma

A

tumour invades through fibrous capsule

invasion either vessels or capsular

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6
Q

histological features of papillary carcinoma

A

intranuclear inclusions
nuclear clearing
nuclear grooves
psammomma bodies (big pink circles)

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7
Q

m:f ratio for hyperthyroidism

A

6:1

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8
Q

prevalence of thyrotoxicosis

A

1 in 100

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9
Q

reference ranges for tsh, t4 and t3

A
  • TSH: 0.4-4.5 milliunits/litre
  • fT4: 9.0-25.0 picomoles/litre
  • fT3: 3.5-7.8 picomoles/litre
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10
Q

what are the most common causes of thyrotoxicosis and in who

A
  • grave’s disease in younger women

- Toxic multinodular goitre in older women

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11
Q

symptoms of hyperthyroidism

A
  • weight loss
  • heat intolerance
  • tremor
  • tachycardia and palpitations: stimulate adrenergic system
  • diarrhoea
  • light or absent menses
  • muscle weakness: catabolism of muscle protein
  • irratbility/ anxiety
  • dyspnoea: increased co2
  • gynaecomastia in males
  • osteoporosis
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12
Q

how does gynaecomastia develop in males in hyperthyroidism

A

liver produces SBHG which binds and inactivates testosterone

-reduced T allows an increased effect of oestrogen on breast tissue

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13
Q

clinical signs on a thyroid exam for hyperthyroid

A

goitre

  • single in grave’s
  • multiple in TMNG

Bruit

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14
Q

what eye signs of hyperthyroidism are specific to Grave’s and not specific to grave’s ie thyroid associated orbitopathy TAO

A

Grave’s

  • gritty
  • redness
  • exopthalmos

non specific -TAO

  • lid retraction
  • lig lag
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15
Q

hand examination for hyperthyroid

A
  • racing pulse
  • palmar erythema
  • thyroid achropacy (digital clubbing, swelling, periosteal reaction)
  • oncholysis
  • tremor
  • sweaty skin
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16
Q

what do you need to ask about in past history for hyperthyroid 2

A
  • asthma in case of beta blocker prescription

- heart disease due to tachycardia complication

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17
Q

what other inx should be done on a patient with hyperthyroid

A

-ecg as can get arrthymias

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18
Q

6 main causes of hyperthyroid

A 
grave's
tmng
thyroiditis
toxic adenoma
exogenous thyroxine-factitious thyroiditis
toxicosis
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19
Q

values for primary hyperthyroid

A

high t3 and t4

low TSH

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20
Q

values for subclinical hyperthyroid

A

normal t3,t4

low tsh

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21
Q

% of hyperthyroid cases caused by grave’s

A

75%

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22
Q

what is grave’s disease path

A
  • autoimmune
  • antibodies attack the thyroid making it overactive
  • organ specific autoimmune disorder
  • IgG autoantibodies attach and stimulate the THS receptors located on the basolateral side
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23
Q

what are the antibodies in grave’s called

A

TRABS tsh receptor antubodies

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24
Q

m:f ratio for graves

A

1:7

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25
Q

triad of grave’s disease

A
  • autoimmune thyrotoxicosis
  • eye disease
  • pretibial myxoedema
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26
Q

other main signs of grave’s

A
  • smooth symmetrical goitre

- bruit

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27
Q 
meaning of these words
chemosis
exopthalmos
lagothalmos 
diplopia
A

eye disease

  • pain
  • chemosis=conjunctival oedema
  • conjuctivitis
  • exopthalmos: bulging
  • lagothalmos: cant close eyelids
  • diplopia : double vision
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28
Q

how is exopthalmos caused in grave’s disease

A
  • swelling of retrobullar tissue mediated by t-cell cytokines and TRAB
  • Trab activate tsh receptors on fibroblast and adipocytes->
  • set off inflammatory process and hydrophilic glycosaminoglyans deposited into extra-ocular muscles in inflammation that cause water retention
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29
Q

dx of grave’s disease

A
  • positive TRAB
  • anti TPO but less specific as also raised in Hashimoto’s
  • scintigraphy scans using 99m technetium pertechnetate or I-131
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30
Q

management of grave’s disease

A
  • antithyroid drugs
  • iodine 131
  • surgery thyroidectomy especially if elderly with heart problems
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31
Q

2 regimens of ATH

A
  • block and replace ie give a high dose ATH and then once under control give I thyroxine
  • titration: achive euthyroidism
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32
Q

what is the chance of remission for graves

A

30-40%

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33
Q

grave’s eye disease management

A
  • steroids
  • cyclosporin in active disease
  • stop smoking
  • antioxidant selenium and topical lubricants
  • wear dark glasses and elevate bed head
  • surgery
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34
Q

what is CI to using radioactive Iodine 131

A

active grave’s eye disease

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35
Q

other autoimmune conditions assoc. to grave’s

A
  • diabetes 1
  • multiple sclerosis
  • vitiligo
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36
Q

% of cases caused by TNMG

A

15%

most common in elderly

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37
Q

what is there a high risk of with Grave’s disease assoc. to cold nodules

A

malignancy

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38
Q

dx of TNMG

A
  • ultrasound and fine needle aspiration

- thyroid isotope

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39
Q

scan of TMNG appearance

A

get nodules of high activity and then other areas are switched off due to feedback on pituitary from nodules

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40
Q

treatment of TMNG

A
  • ATD to achieve euthyroidism and

- I131 as wont achieve remsission without this

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41
Q

what is thyroiditis

A

temporarily overactive thyroid followed by underactivity

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42
Q

what causes thyroiditis

A
  • prenancy
  • infection eg viral
  • drugs eg amiodarone
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43
Q

dx of thyroiditis

A
  • no uptake of technetium on thryoid scan
  • raised CRP and ESR
  • raised TFT
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44
Q

what is deQuervian thyroditis

A
  • painful thryoid
  • subacute thyroiditis
  • illness causes release of pre-made thyroid hormones
45
Q

what is post-partum thyroiditis and prevalence

A
  • 5-10% women

- hyperthyroid phase within4-6 months of delivery then hypot then euthyroid

46
Q

management of thyroiditis

A
  • self limiting as will progress to hypo
  • can give beta blockers in thyrotoxic phase
  • dequervian for pain give NSAID
47
Q

toxic nodule treatment

A
  • I131
  • ATD
  • thyroidectomy
48
Q

what is thyrotoxic crisis and symptoms

cardinal signs

A
  • life threatening hyperthyroidism
  • reduced conscious level
  • hyperthermia
  • multisystem organ fail

cardinal signs

  • fever
  • confusion
  • dehydration
49
Q

what can precipitate thyrotoxic crisis

A
  • thyroid surgery
  • radioiodine
  • certain contrast agents
  • atd withdrawal
  • acute illness
50
Q

treatment of thyrotoxic crisis

A
  • high dose ATD
  • potassium iodine
  • beta blockers
  • steroids
51
Q

what is apathetic hyperthyroidism

A
  • lack the adrenergic system eg the tremor, heart rate
  • usually in elderly
  • often misdiagnosed as mimics depression
52
Q

what is resistance to thyroid hormones

A
  • when tissues are less responsive to TH

- high t3/t4 with normal or elevated TSH

53
Q

what is T3 toxicosis

A

excess t3 produced by thyroid without increase in T4

-seen in tmng or early grave’s

54
Q

management of hyperthyroid

A
  1. beta blocker propanolol for tremor
  2. selenium for eye
  3. ATD carbimazole and propylthirouracil
  4. radioactive iodine I131
55
Q

how do ATD work

A

interefer with TPO thryoid peroxidase to decrease thyroid hormones

56
Q

3 main side effects of carbimazole

A
  1. rash
  2. pruritius
  3. agranulocytosis
57
Q

prevalence of agranulocytosis and what is it and what to warn patients

A 
<1/100
-life threatening leucopaenia where patient immune system is compromised due to lack of granulocytes especially neutrophils
warn patients of
-high temperature
-sore throat
-mouth ulcers
58
Q

side effect of propylthiouracil

A

can affect the liver and cause hepatotoxicity

59
Q

when should propylthiouracil be given instead of carbimazole

A

in pregnancy to avoid agranulocytosis

60
Q

effectiveness of RI 131

A

90% respond after one dose

61
Q

adverse of I131

A

long term hypothyroidism is almost inevitable and should be warned about

62
Q

what is I131 contraindicated in

A
  • children
  • pregnancy
  • lactating women
  • active grave’s eye disease
  • vomiting or incontinent urine
63
Q

precautions that must be taken after I131

A
  • have to sleep in own bed for 4 days
  • avoid close contact with children <12 years and pregnant women for 12 days
  • then avoid >15 minutes for 25 days
  • avoid pregnancy or breast feeding for 6month
  • men avoid pregnancy for 4 months
  • wear disposable gloves with food prep for 14 days
  • use own cutlery
64
Q

indication for thyroidectomy

A
  • large goitre
  • severe
  • intolerance to ATD
  • RAI is CI
  • poorly controlled in pregnancy
  • severe eye disease
65
Q

side effects of thyroidectomy

A 
hypoparathyroidism post surgery
recurrent laryngeal nerve palsy-hoarse voice 
hypocalcaemia
haemorrhage
thyroid storm
66
Q

cause of hyperthyroidism in neonates

A
  • usually due to grave’s

- trabs can pass from mother to foetus via the placenta

67
Q

formation of t3 and t4

A
  1. Trap the iodine from plasma
  2. Oxidation of iodine by a thyroid peroxidase using h2o2
  3. Incorporation of iodine into tyrosyl residues on thyroglobulin to make mono and di-iodotyrosine
  4. Coupling of iodotyrosyl residues to make t4, t3 and rt3 on thyroglobulin
  5. Re-absorption of colloid into cell
  6. Thyroglobulin proteolysis
  7. Release of t4 and t3
68
Q

what is T4 bound to in the blood and %

A
  1. 95% bound
    - thyroxine binding globulin 70%
    - transthyretin 20%
    - albumin 10%
69
Q

where is t3 produced

A

20% in the thyroid

80% is from t4 conversion at liver, kidney and muscle

70
Q

ratio of t3/t4

A

1:14

71
Q

prevalence of hypothyroidism

A

15 in 1000 women and 1in 1000men

72
Q

causes of hypothyroidism

A

hashimoto

  • spontaneous atrophic
  • (iodine deficiency)
  • temporary thyroiditis
  • iatrogenic post surgery or post radiation
  • congenital
  • dysmorphogenesis
73
Q

primary hypothyroidism markers

A

high tsh
low T4
low/n t3

74
Q

subclinical hypothyroidism markers

A

high TSH

normal t3 and t4

75
Q

secondary hypothyroidism

A

low TSH
low t4
lowt3

76
Q

non thyroidal illness

A

low tsh
high t4
low t3

77
Q

symptoms of hypothyroidism

A
  • tired
  • cold intolerance
  • weight gain and puffy
  • slow HR
  • constipation
  • heavy periods menorrhagia
  • dry skin and coarse hair
  • goirtre
  • hyperlipidaemia and hypercholestrolaemia
  • carpal tunnel syndrome-pain in hands
  • myxoedematous: hoarseness and deafness
  • slow relaxing reflexes
78
Q

inx of hypothyroidism

A
  • low free t4, high TSH and anti-tpo antibodies

- hyperlipid and hypercholesterol

79
Q

what is hashimoto thyroditis and how do patients often present

A
  • antibodies against TPO

- often euthyroid as only 25% hypot on presentation

80
Q

what is hashitoxicosis

A

initial release of preformed thyroid hormones=transient hyperthyroidism

81
Q

most common cause of hypot in the UK

A

spontaneous atrophic/ myxoedema thyroid

82
Q

what causes spontaneous atrophic hypothyroid

A
  • thyroid infiltrate with lymphocytes (hallmark of chronic inflammation)
  • destroy follicular cells lining the thyroid follicles
  • fibrous tissue and atrophy
83
Q

how does dysmorphogenesis cause hypothyroidism

A
  • bad hormone synthesis ie abnormal
  • specific inborn errors of metabolism eg inability to trap iodine, deficiency in iodination of thyroglobulin, defects in thryoglobulin metabolism
84
Q

what syndrome is deficiency in iodination of thyroglobulin part of

A

Pendred syndrome

85
Q

what is used to dx congenital hypothyroidism

A

heel prick

86
Q

prevalence of congenital hypothyroid

A

1 in 3,500-4,000

87
Q

what causes and what are the risks of congenital hypothyroid

A
  • mother doesnt have enough iodine in pregnancy

- risk of creinism=stunted physical and mental growth

88
Q

what drugs induce hypothyroidism

A

lithium

amiodarone

89
Q

what causes scondary hypothyroidism

A

panhypo-pituratism ie low pituitary TSH produce

90
Q

symptoms of pituitary failure

A

-sexual dysfunciton-hypogonadism
-tiredness-hypoadrenal
dizzy-low bp
-bitemporal hemianopia if tumour in pituitary pressing on optic chiasm

91
Q

management principle of hypopituratism

A

replace cortisol first then replace thyroid otherwise get hypoadrenal crisis

92
Q

what is sheehan’s syndrome

A

severe blood loss during labour can cause an infarction in pituitary secondary to hypotension causing hypopituratism

93
Q

what is myxoedema coma

A

rare severe life threatening hypothyroidism precipitated by infection
-reduced consciouss level, hypothermia, resp depression

94
Q

treatment myxoedema coma

A
  • t3/t4 administer
  • antibiotic cover after culture
  • steroid cover as assoc. to adrenal dysfunction
95
Q

main cause of subclinical hypothyroidism

A

-autoimmune chronic thyroiditis

but doesnt really cause symptoms other than cardiac adverse lipids..

96
Q

what drug is used in hypothyroidism

A

levothyroxine t4 replacement drug which is converted to t3 active

97
Q

what happens if you take too much levothyroxine and needs to be cautioned in who

A

can get factitious hyperthyroidism that can lead to arrhythmias
-so in heart disease start on low dose as it increases o2 demand of tissues

98
Q

effectiveness of levothyroxine

A

-doesnt work for all so others want to use t3 or dessicated but not available

99
Q

how to take levothyroxine

A

empty stomach before breakfast

100
Q

medications that impair t4 absorption and advice

A

-proton pump inhibitors
-h2 antagonist eg rantidine
-some antacids
-calcium and iron supplements
so dont take within 4 hrs of these meds

101
Q

what medication means t4 requirement needs to be increased and why 2

A

-starting oestrogen (OCP, HRT)
-anti-convulsants eg epilepsy
both induce liver enzymes that break down thyroxine

102
Q

what is liothyronine

A

t3 replacement

103
Q

how does non-thyroidal illness affect t3/t4

A

low levels of TSH and T3 can also be caused by NTI

-Acute illness – may cause elevated FT4 and suppressed TSH

104
Q

how does non-thyroidal illness suppress tsh

A
  • range of mechanism: IL1, TNFa, glucocorticoids
  • TRH release suppressed by cytokines and glucocorticoids
  • some drugs eg dopamine inhibit TSH release

rises on recovery

105
Q

what converts t3 to t4

A

deiodinases

106
Q

what causes hypothyroidism in pregnancy

A

foetus needs t4 so uses maternal t4 so requirenment increases by 50% so need to increase dose

107
Q

what can untreated overt hypot in pregnancy lead to

A
  • infertility
  • miscarriage
  • pre-eclampsia
  • premature delivery
  • increased foetal mortality
  • impaired neurological development
  • neurodevelopmental delay
  • placental abruption
108
Q

what hormones should be checked in pregnancy

A

free t3 and t4 as TBG increases in pregnancy due to oestrogen so give false result

109
Q

grave’s triad

A

thyroid eye disease
thyroid acropachy
pretibial myxoedema

Endocrine (14 decks)

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