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Thyroid Flashcards

1
Q

What is TSH and what does it do?

A

Thyroid-stimulating hormone
Thyrotropin
Glycoproteins produced by the anterior pituitary
Stimulates the thyroid gland

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2
Q

What does the thyroid gland produce

A

Mainly T4 some T3
T3 is 5 fold more active than T4
T4 is activated in the peripheries

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3
Q

How is T3 and 4 transported in the blood

A

Most is bound in the plasma to thyroxine binding globulin

The unbound portion is the active part

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4
Q

What are the action of T3 and 4

A

Inc cell metabolism
Via nuclear receptors
Vital for growth and mental development
They also inc catecholamine affects

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5
Q

What are thyroid hormone abnormalities caused by

A

Usually due to problems in the thyroid itself rarely problems in the hypothalamus or pituitary

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6
Q

Basic thyroid hormone tests

A

Free T3&4

Not total because this is affected by TBG when TBG in so will Total T3&4

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7
Q

When is TBG increased

A

Pregnancy, oestrogen therapy HRT COCP and hepatitis

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8
Q

When is TBG dec

A 
Nephrotic syndrome - protein loss
Malnutrition - protein loss
Drugs- corticosteroids, phenytoin
Chronic liver disease 
Acromegaly
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9
Q

What tests to order when hyperthyroidism in suspected

A

Ask for T3 T4 and TSH

All types have dec TSH except for rare pit secreting adenoma most have raised T4

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10
Q

What tests to order when hypo thyroid suspected

A

Only T4 and TSH
T3 no extra info
Sh varies through the day so try to do it at the same time each day

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11
Q

What is sick euthyroid

A

Any systemic illness TFTs mayb become deranged
Typical pattern is everything low
Tests should be repeated after recovery

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12
Q

Other tests to do in thyroid

A 
Thyroid autoab
TSH receptor Ab
Serum thyroglobulin 
US
Isotope scan
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13
Q

What autoantibodies to do

A

TPO - Antithyroid Peroxidase

Antithroglobulin ab

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14
Q

What is associated with which ab

A

TPO - hashimotos
antithyroglobulin - graves or hashimoto
TSH receptors Ab inc graves

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15
Q

Hat is useful in the tx of carcinoma monitoring

A

Serum thyroglobulin

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16
Q

What is an USS scan used for

A

This distinguishes cystic (usually but not alway benign) from solid (usually malignant) nodules
Can then take FNA from the nodules to determine if it is cancerous and what types of cancer

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17
Q

Types of thyroid cancer

A 
Follicular 
Medullary - c cells so may produce calcitonin may be a part of MEN 2 syndrome - need to perform a phaeochromocytoma screen  
Anaplastic 
Papillary - most common 
Lymphoma
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18
Q

What is an isotope scan used for

A

Iodine or technetium pertechnetate
Useful for determining cause of hyper thyroidism & to detect a retrosternal goitre, ectopic thyroid tissue or thyroid mets (+whole body CT)
If there are suspicious nodules the question is are they hot or cold

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19
Q

Isotope scan hot nodule what does it mean

A

Increased up take is a hot nodule and these aren’t typically malignant

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20
Q

What does a neutral nodule mean on an isotope scan

A

Doesn’t take up anymore radio isotope than any other area on the thyroid
These aren’t typically malignant

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21
Q

What does a cold area mean on an isotope scan of the thyroid

A

The area takes up less radio isotope than the rest of the thyroid
20% of cold nodules are malignant

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22
Q

When is surgery most likely needed on thyroid nodules

A 
Rapid growth 
Compression signs 
Dominant nodule on scintigraphy - dominant nodule on reader of the isotope 
Nodule same or bigger than 3cm
Hypo-echoenicity
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23
Q

What abnormalities should be screened for those with thyroid dysfunction

A 
AF
Hyperlipidaemia
DM
T1DM in1st trimester and post delivery 
Patients on amioderone or lithium 
Patients with Downs or Turners Syndrome
Addison’s disease
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24
Q

What does inc TSH and low T4 mean

A

Hypothyroidism

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25
Q

What is inc TSH and normal T4

A

Patient doesn’t regularly take their replacement medication

Or subclinical hypothyroidism

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26
Q

Inc TSH and inc T4

A

TSH secreting tumour or thyroid hormone resistance

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27
Q

Inc TSH and inc T4 and dec T3

A

Slow conversion to the active form T4 to T3
Deiodinase deficiency, euthyroid hyperthyroxaemia
Thyroid hormone antibody artefact

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28
Q

Dec TSH inc T4 and inc T3

A

Hyperthyroidism

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29
Q

Dec TSH and normal T4 and T3

A

Subclinical hyperthyroidism

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30
Q

Dec TSH and dec T4

A

Central hypothyroidism (hypothalamic or pituitary disorder )

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31
Q

Dec TSH dec T4 and T3

A

Sick euthyroid

Pituitary disease

32
Q

Normal TSH abnormal T4

A

Consider changes in the thyroid-binding globulin, assay interference, amioderone, pituitary TSH tumour

33
Q

What is thyrotoxicosis

A

Excess thyroid hormone usually from gland hyperfunction

34
Q

Symptom of thyrotoxicosis

A 
Diarrhoea
Dec weight
Inc appetite 
Can get paradoxical weight gain in 10%
Over active 
Sweats 
Heat intolerance 
Palpitations
Tremor
Irritability 
Labile emotions
Oligomenorrhoea
\+/- infertility 
Rare psychosis, chorea, panic, itch , alopecia, urticaria
35
Q

Signs of thyrotoxicosis

A 
Inc HR/irregular - AF, SVT, rare VT
Warm moist skin 
Fine tremor
Palmar erythema 
Thin hair 
Lid lag 
Lid retraction 
Potential goitre
36
Q

Signs of Graves’ disease

A

Eye disease - exophthalmos, proptosis, conjunctival oedema, corneal ulceration, papilloedema, loss of colour vision.
Pretibial myxoedema - swelling above the lateral malleoli
Thyroid acropatchy - clubbing, periosteal action in limb bones

37
Q

Test results in hyperthyroidism

A 
Inc T4 and T3 
Dec TSH 
May be mild normocytic anaemia 
Mild neutropenia
Inc ESR 
Inc ca2+
Inc LFT
Check thyroid autoantibodies 
If cause unclear may want isotope scan 
Eye disease - ophthalmoscope , visual fields, acuity, eye movements.
38
Q

What are the causes of thyrotoxicosis

A 
Graves’ disease
Toxic multinodular goitre
Toxic adenoma
Ectopic thyroid gland tissue 
Exogenous
39
Q

What is the most common cause of hyperthyroidism

A

Graves’ disease

40
Q

What is the prevalence and cause of Graves’ disease

A

More common in women age 40-60
Cause circulating IgG autoantibodies binding to & activating G-protein coupled thyrotropin receptors which are smooth thyroid enlargement and hormone production particularly T3 and react to orbital autoantigens

41
Q

Triggers of Graves’ disease

A

Stress
Infection
Childbirth

42
Q

Are patients always hyperthyroid in graves

A

Most hyper but can be eu and hypo

43
Q

Is graves associated with autoimmune diseases

A

Yes
Vitiligo
T1DM
Addisons

44
Q

Who gets toxic nodular goitre

A

Elderly

Iodine deficient areas

45
Q

What does a toxic multi nodular goitre do

A

Nodules secrete hormones

46
Q

Tx of toxic multinodular goitre

A

Tx same as graves
If compressive surgery is indicated
- dysphagia or dyspnoea

47
Q

What is a toxic adenoma

A

Solitary nodule producing T3 and T4
On isotope scan hot nodule
And the rest of the gland is suppressed

48
Q

What is ectopic thyroid tissue

A

Metastatic follicular thyroid cancer

Struma overii -ovarian teratoma with thyroid tissue

49
Q

What is subacute de quervains thyroiditis

A

Self limiting post viral with painful goitre inc temperature +/- inc ESR
Tx NSAIDs

50
Q

Tx hyperthyroidism

A

Drugs
Beta blockers - propranolol control rapid symptoms
Treat the condition - these drugs are used to decrease thyroid hormone synthesis by acting as a preferred substrate or iodisation by thyroid peroxidase the key enzyme in thyroid hormone synthesis
- carbimazole and propyluracil
2 regimens for carbimazole - titrate it up and give carbimazole and Levothyroxine at the same time
Prpyluracil is a second line due to the small chance of liver toxicity
Surgical - radioiodine tablet
Hasn’t been shown to inc risk of cancer Roth defects or infertility in women
CI in pregnancy , lactating and you need to be kept further away from children when you have the tx
Thyroidectmy usually total risk = damage to recurrent laryngeal nerve = hoarseness and lack of voice
Radioidione and thyroidectomy - become hypothyroid so need replacement but is better than potential longterm effects of being hyper and the medication se

51
Q

Complications of hyperthyroidism

A 
Heart failure - thyrotoxicosis cardiomyopathy 
Angina
AF
Osteoporosis
Ophthalmology 
Gynacomastia 
Thyroid storm
52
Q

What causes thyroid eye disease

A

Retro orbital inflammation and lymphocyte infiltration resulting in swelling of the orbit

53
Q

What is the main risk factor for thyroid eye disease

A

Smoking

54
Q

Prevalence of thyroid eye disease

A

25-50% of those with Graves’ disease

55
Q

Does the eye disease correlate with thyroid disease

A

May not

The patient could be euthyroid, hypo or hyper

56
Q

How does thyroid eye disease present

A

It was be the first presenting feature of graves

And can be worsened by tx typically radioiodine but is typically transient

57
Q

Symptoms of thyroid eye disease

A 
Eye discomfort
Grittiness
Inc tear production 
Photophobia 
diplopia
Dec acuity 
RAPD - may mean optic nerve compression, depression may be needed get help at once
58
Q

Does eye protrusion mean nerve damage

A

No

If the eye cannot protrude more likely to lead to optic nerve compression

59
Q

Signs of eye disease

A

Exophthalmos - appearance of protruding eye
Proptosis - eye protrude beyond the orbit
Conjunctival oedema
Corneal ulceration
Papilloedema
Loss of colour vision
Ophthalmoplegia

60
Q

Test for thyroid eye disease

A

The diagnosis is clinical so none needed

A ct/mri would show enlarged eye muscles

61
Q

Mx of thyroid eye disease

A

Con - stop smoking
Med - symptoms: artificial tears, sunglasses, avoid dust
Diplopia - fresnel prism on lens
More severe may need high dose steroids
Surg - surgical decompression in severe sight threatening conditions eye lid surgery for cosmesis & function
Orbital radiotherapy - used to treat ophthalmoplegia
Future: anti TNF alpha antibodies - infliximab

62
Q

Causes of goitre

A

Physiological
Graves’ disease
Hasimotos thyroiditis
Subacute (de Quervain’s thyroiditis) - painful

63
Q

What is the first line treatment in toxic nodular goitre

A

Radioiodine

64
Q

What happens in the pituitary in Graves’ disease

A

TSH is suppressed

And the expression of thyrotropin beta subunit

65
Q

What happens to the heart in Graves’ disease

A

Inc rate
Inc contractility
Inc serum atrial beta natriuretic peptide

66
Q

What is hypothyroidism

A

Clinical affect of a lack of thyroid hormone

67
Q

Symptoms of hypothyroidism

A

Tiredness, sleepy, lethargic, dec mode, cold-disliking,inc weight, constipation, menorrhagia, hoarse voice, dec memory and cognition, myalgia, cramps, weakness

68
Q

Signs of hypothyroidism

A 
BRADYCARDIA 
R = reflexes slow
A = ataxia 
D = dry/thin skin
Y = yawning/ tired 
C = cold hands
A = ascites
R= round puffy face/double chin
D= demeanour - low
I = immobile 
C=CCF
69
Q

Diagnosis of hypothyroidism

A

TFTs
Low T4/3
High TSH
Rare secondary from pituitary both low

70
Q

Causes of primary autoimmune hypothyroidism

A

Primary atrophic hypothyroidism = diffuse lymphocytic infiltration of the thyroid, leading to atrophy, no goitre
Hashimoto’s thyroiditis = goitre due to lymphocytic and plasma cell infiltration, ab TPO antithyroglobulin high
Worldwide = iodine deficiency
Post thyroid radioiodine tx or thyroidectomy
Drug induced - amioderone, lithium

71
Q

Associations with hypothyroidism

A

Other autoimmune conditions

  • Addison’s, T1DM, pernicious anaemia
  • turners and Down’s syndrome, CF, PBC, ovarian hyper stimulation, POEMS syndrome - poyneuropathy, organomegaly, endocrinopathy, m-protein band (plasmacytoma)+ skin pigmentation/tethering
72
Q

Problems in pregnancy in hypothyroidism

A 
Eclampsia
Anaemia
Prematurity
Low birthweight
Stillbirth
PPH
73
Q

Tx hypothyroidism

A

Young give Levothyroxine and titrate to clinical picture

Elderly give 25 to start and adjust accordingly

74
Q

What does amioderone do to the thyroid gland

A

It is an iodine rich drug
Structural like T4
Hypothyroidism as T4 can be inhibited due to iodine excess
Hyperthyroidism can be caused by toxic thyrotoxicosis which causes hormone release
Check tft monthly on amioderone
If cannot stop amioderone then a thyroidectomy may be needed

75
Q

What is the state before death in hypothyroidism

A

Myxoedema coma

76
Q

What is subclinical hypothyroidism

A

TSH >4
Normal T4 and T3 no symptoms
Small risk of progression to hypothyroidism
This inc the higher the TSH, male, and if you have TPO ab
May need treating see if they get any better

77
Q

What Is subclinical hyperthyroidism

A

TSH low
Normal T4/T3
Rule out rare secondary hyperthyroidism - central cause, pregnancy, illness

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