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Endocrine > Thyroid > Flashcards

Thyroid Flashcards

1
Q

Use of TPO antibodies

A

suspected hashimotos thyroiditis
not usually needed for diagnosis
has predictive value for determining risk of development of overt hypothyroidism
Postpartum thyroiditis occurs in 30% of women with elevated levels.

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2
Q

TSH receptor antibody use

A

graves disease but not usually needed for diagnosis- usually would use radioiodide uptake unless contraindicated ie pregnant

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3
Q

Clinical use of serum thyroglobulin

A

suspected subacute thyroiditis or suspect surreptitious ingestion of thyroxine
Can be used as tumour marker in people with well differentiated thyroid cancer.
Remember that difficult to interpret when thyroglobulin antibodies

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4
Q

Why do you not measure T3 in hypothyroidism?

A

Because T3 levels are often conserved even if there is signifiant hypothyroidism

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5
Q

Increased anti TPO ab and anti thyroglobulin antibodies think…

A

Hashimotos

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6
Q

Elevated thyroid stimulating immunoglobulins and thyrotropin binding inhibitory immunoglobulins (TBIIs) think….

A

Graves

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7
Q

What could you measure in a patient with a family history of autoimmune hypothyroidism to determine future risk:

A

anti-TPO ab (NOT anti-thyroglobulin Ab) - but no value for serial measurement unless wanting to get pregnant (higher risk preterm delivery, miscarriage, infertility)

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8
Q

why measure serum thyroglobulin?

A

Low levels in serruptitious thyroxine
High levels in hyperthyroidism and thyroid destruction
Tumour marker for well differentiated papillary or follicular ca
Need to measure serum thyroglobulin ab at same time- if ab present then level of thyroglobulin not a reliable test

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9
Q

Why measure serum calcitonin

A

Secreted from C cells in thyroid gland
Tumour marker in medullary Ca
Don’t measure in everyone with a thyroid nodule, but should measure if FB thyroid Ca, features of MEN2, or biopsy shows medullary

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10
Q

Causes of thyrotoxicosis

A 
Grave's
TMNG
Toxic adenoma
TSH secreting pituitary adenoma
Exogenous T4/T3
Iodine load- Jod-Basedow
Lingual thyroid
Amiodarone
Thyroiditis- acute/subacute/postpartum/silent/Hashimoto/Drug induced/Traumatic/Riedel/radiation
hCG mediated- gestational thyrotoxicosis- usually with hyperplacentosis- molar preg or multiple preg
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11
Q

If TSH is high/normal with high T3 or 4 and suspect TSH secreting tumour, then can do a…

A

alpha subunit to serum TSH ratio which will be more than one if tumour is source

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12
Q

When to chose methimazole

A

Most cases as better side effect profile (hepatic)

NOT in pregnancy-teratogenic

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13
Q

When to choose propylthiouracil

A

First trimester of pregnancy.

Worse side effects- mainly hepatic

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14
Q

MEchanism of action of methimazole

A

Inhibits TPO–>no conversion of iodide to iodine which facilitates attachment to thyroglobulin

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15
Q

Methimazole and propylthiouracil can cause…

A

agranulocytosis
LFT derangements
drug rash in 5-10 percent

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16
Q

Why should you avoid thyroid ablation in graves ophthalmopathy?

A

Can worsen at least transiently

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17
Q

Graves ophthalmopathy signs

A

lid retraction
chemosis
lid lag
cannot close eyes completely (lagophthalmos)
widened palpebral fissure
eye globe lag on supraduction
epithelial errosions
inferior rectus myopathy–>vertical diplopia
optic nerve damage–>emergency, blindness

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18
Q

Jod-Basedow phenomenon

A

Where an iodine load from contrast induces thyrotoxicosis in a patient who already has a degree of autonomy from TSH due to activating somatic mutation in receptor

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19
Q

Graves disease features

A 
Generic features of thyrotoxicosis
Thyroid ophthalmopathy
Pre-tibial myxoedema
Thyroid acropachy
Goitre with anatomical enlargement
20
Q

Thyrotoxicosis any cause

A 
Anxiety
Tremor
Weight loss
Sweating
Increased appetite
Heat intolerance
Diarrheoa
oligomenorrhoea
weakness
palpitations
dyspnoea/chest pain/reduced exercise tolerance
21
Q

Decreased visual acuity in graves what mechanism?

A

Pressure on optic nerve from oedema

22
Q

Complications of Grave’s diseas

A 
Myopathy
Psychosis
Hypokalaemic periodic paralysis, associated myasthenia
AF, high embolic risk
Heart failure
Osteoporosis
Pigmentation, thin skin, onycholysis
neutropenia, lymphocytosis, thrombocytopaenia
23
Q

In Graves, when would you be more likely to start antithyroid drug? (as opposed to radiation or surgery)

A

Pregnant- but second trimester uncontrolled thyrotox use surgery. ALSO CARBIMAZOLE CAUSES FETAL SYNDROME BEFORE 12 weeks.
Patients less than 40
small goitre
low titre thyroid antibodies

In old patients, males, large goitre, large titre TRAB, unlikely to spontaneously remit and so ablative therapy may be more appropriate

24
Q

When to avoid radioiodide treatment for Graves

A

Large goitre- may only reduce slightly
May exacerbate graves ophthal- can give steroids to try and protect
Dont use in pregnancy and only cautiously in patients of reproductive age

25
Q

Carbimazole counselling

A

Idiosyncratic agranulocytosis in 0.4% - idiosyncratic and no point in monitoring- stop takind drug if unexplained febrile, mouth ulcers, sore throat.

Carbimazole and propythiouracil 10% risk rash
Propylthiouracil rare fatal hepatotoxicity so not first line

26
Q

Why are thionamides nor as good in TA or MNG?

A

due to a constitutive mutation and spontaneous remission unlikely. Probably won’t induce remission with drugs

27
Q

When to treat subclinical hyperthyroidism- sub normal TSH with normal T3 and T4

A

1-2% risk progression to overt disease per year, more if MNG
if TSH less than 0.1- risk of progression, AF, CCF, ostroporosis
Treat if existing heart disease or osteoporosis, MNG

28
Q

Hypothyroidism features

A 
Cold
Fatigue/lethargy
Reduced appetite
menorrhagia
weight gain
 thin hair loss
dry coarse skin
oedema
memory loss
depression and anxiety
thick tongue slow speech
constipation
29
Q

By what proportion do you need to pre-emptively increase thyroxine in pregnancy

A

50% v

30
Q

Subclinical hypothyroidism (raised TSH in setting of normal T3 and T4)

A

natural progression to hyothyroidism 2.5% per year, all need to be followed up, higher risk if antibodies present
Treat to prevent hypothyroidism if TSH over 10 no evidence of benefit (symptoms do not improve in studies) if TSH less than 10
Also treat if TSH over 2.5 and pregnant or thinking about being pregnant
Treat if Under 65
If heart failure

31
Q

Clinical features of De-Quervain’s thyroiditis AKA subacute thyroiditis- VIRAL CAUSE

A

Painful, swollen thyroid, jaw pain, hoarse voice
Constitutional symptoms, fever
Thyrotoxicosis features
Sx last 2-8 weeks

32
Q

Tests in De-Quervain’s AKA subacute thyroiditis- VIRAL

A

ESR and CRP up
Thyroglobulin elevated
isotope scan low or absent uptake
USS large hypoechoic gland with reduced vascularity

33
Q

Treatment of subacute thyroiditis

A 
NSAID/aspirin if mild
pred 40mg then taper otherwise
propanolol or metoprolol for sx
thionamides INEFFECTIVE
thyroxine in hypothyroid phase
34
Q

Outcome in subacute thyroiditis

A

90% resolve, 10% stay hypothyroid

can have recurrent episodes

35
Q

Lymphocytic and post partum thyroiditis clinical features

A 
painless enlargement of thyroid gland + thyrotoxicosis
low echogenicity on USS
low uptake on scan
high thyroglobulin
aTPO and TG antibodies
bx lymphocytic infiltration
common presentation post partum
thyrotoxicosis-->hypothy-->20-30% persisting hypothyroid
antithyroid drugs NOT useful
36
Q

What is Riedel’s thyroiditis

A

Fixed painless mass + eu/hypothyroidism
Dense fibrosis extending to adjacent structures, associated Hornders, carotid stenosis, hypoparathyroidism
probably on the spectrum of IgG4 disease
Tx surgery, steroids, mycophenolate, tamoxifen

37
Q

bad nodule features on USS

A

hypoecoic, microcalcification, taller than wide, irregular margins, broken egg shell rim
IF not a HOT nodule on isotope uptake and over 2cm then biopsy, if 1-2 cm then decide based on USS features if under 1cm then do in 6-12 months USS- if increase 30% on USS in volume or 10% diameter –>bx

38
Q

when to treat subclinical hyperthyroidism?

A

AF
Osteoporosis
Symptoms
TSH under 0.1

39
Q

Types of amiodarone induced thyroid disorder-

A

Hypothyroidism due to Wolff-Chaikoff effect (saturated NI symporter due to iodine load from amiodarone)

Hyperthyroidism

  1. type 1 from Jod Basedow iodine load -treat with carbimazole or PTU
  2. Type 2 from thyroiditis and hormone release- replace with steroids
40
Q

Lithium effect on thyroid gland

A

Li inhibits T4 production and secretion –>hypothyroidism

May also cause thyroiditis

41
Q

Good features on ultrasound of lump?

A 
Cyst simple
spongiform
Partially cystic
Hyperechoic
Solid, regular margin
42
Q

Mutations in thyroid cancers?

A

Medullary- RET
Follicular- PAX8/PPARgamma- very specific
Papillary - BRAF most common

43
Q

“normal” effect of amiodarone on thyroid

A

Blocks T4 to T3 conversion so usually see increase T4 and reduced T3 from baseline
Usually see increase in TSH slightly
usually see slight increase in rT3
After 3-6 months reach steady state and TSh normal, T4 ULN, T3 low normal

44
Q

Lithium causes what type of thyroid trouble?

A

More commonly hypothyroidism

Also hyperthyroidism

45
Q

Hashimotos associated with which cancer?

A

Primary thyroid lymphoma

Rapidly enlarging goitre, firm, with fever

Endocrine (12 decks)

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