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ENT (Throat) > Thyroid Dysfunction and Nodules > Flashcards

Thyroid Dysfunction and Nodules Flashcards

1
Q

The vast majority of metabolic thyroid disease is due to a primary abnormality of the thyroid gland itself. True or false?

A

True in 98% of cases

It is very rare for a pituitary adenoma to produce TSH and lead to thyrotoxicosis and pituitary failure very rarely presents with isolated hypothyroidism

This means TSH levels can be used as a screening test for hyper or hypothyroidism

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2
Q

What happens with regards to TSH and free T4 in hyper and hypothyroidism?

A

Hyperthyroidism: TSH decreased and free T4 increased

Hypothyroidism: TSH increased and free T4 decreased

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3
Q

What is a goitre?

A

Refers to a thyroid swelling

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4
Q

What different types of goitre are there?

A

Diffuse
Multinodular
Single nodule

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5
Q

What is the prevalence of goitre in UK?

A

7% of females
1% males

Not known why more common in females - the oestrogen/progesterone ratio may affect thyroid function

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6
Q

When can physiological goitre (normal thyroid function) occur at?

A

Menarche
Pregnancy
Menopause

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7
Q

What are the commonest causes of goitre globally?

A

Iodine deficiency - reduced thyroxine levels lead to increased TSH -> generalised thyroid enlargement (usually nodular)

Multi nodular goitre - cause unknown, normal thyroid function although after many years small number may develop hyperthyroidism = toxic mutinodular goitre

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8
Q

What is the commonest cause of goitre in UK?

A

Multinodular goitre

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9
Q

What areas are more likely to be iodine deficient?

A

Mountainous areas (iodine high in sea)

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10
Q

A goitre may accompany hyper or hypothyroidism. True or false?

A

True, but not necessary present in either

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11
Q

When is iodine deficiency a particular concern?

A

During pregnancy - if mother is iodine deficient and hypothyroid, then the foetus is also iodine deficient.

Leads to a child with: mental retardation, abnormal gait, deaf-mutism, short stature, goitre, hypothyroidism

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12
Q

What can cause hypothyroidism?

A

Autoimmune destruction - Hashimoto’s disease
Severe iodine deficiency
Thyroiditis
Thyroidecromy or radioactive iodine treatment
Over response to hyperthyroidism drug treatment

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13
Q

How many women over 30 have Hashimoto’s thyroiditis?

A

10%

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14
Q

What antibodies are present in the blood with Hashimoto’s thyroiditis?

A

Antibodies to thyroglobulin and thyroid peroxidase

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15
Q

Can you get a goitre with Hashimoto’s disease?

A

Yes in early stages may be associated with small diffuse goitre (due to inflammation) or the thyroid may never enlarge and shrink in size from beginning

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16
Q

How is hypothyroidism treated?

A

Oral thyroxine

Adjust dose to normalise serum TSH

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17
Q

What symptoms are associated with hypothyroidism?

A 
Excessive tiredness
Memory problems, depression, psychosis
Weight gain
Cold intolerance 
Gruff voice
Puffy eyes, face, hands, feet
Dry, flaky skin
Hair loss, particularly outer 1/3 eyebrows
Symptoms of carpal tunnel syndrome
Constipation 
Menorrhagia
Muscle weakness and cramps g
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18
Q

What signs are associated with hypothyroidism?

A

Weight gain
Dry skin, brittle hair, loss of outer 1/3 eyebrows
Pallor - peaches and cream face
Coarse facial features, periorbital puffiness
Bradycardia
Hyporeflexia
Non pitting oedema - myxoedema (due to deposition of polysaccharides particularly around eyes, hands, feet)
Ascites or pericardial effusion (uncommon)

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19
Q

What causes hyperthyroidism?

A

Graves’ disease
Toxic multinodular goitre
Toxic adenoma

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20
Q

Describe Graves’ disease

A

An autoimmune disease. They thyroid component is caused by a circulating immunoglobulin called thyroid stimulating immunoglobulin (TSI) - attaches to and stimulates the TSH receptor.

TSI causes all of the classical signs and symptoms of thyrotoxicosis and additional unique features of Graves :

  • exopthalmos
  • pre tibial myxoedema
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21
Q

What is exophthalmos seen in Graves?

A

An abnormal protrusion of the eye resulting from swelling of tissue, muscle and fat in socket behind eye

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22
Q

How is thyrotoxicosis treated?

A

Carbimazole - prevents thyroid peroxidase from coupling and iodinating the tyrosine residues on thyroglobulin, thereby reducing production of T4

Thyroidecromy

Ablative dose of radioactive iodine

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23
Q

What symptoms are associated with hyperthyroidism?

A 
Overactivity, tiredness
Nervousness, anxiety, insomnia 
Shaking, trembling
Heat intolerance
Increased sweating - warm, sweaty hands
Palpitations 
Diarrhoea 
Amenorrhea
Proximal muscle weakness
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24
Q

What signs are seen in hyperthyroidism?

A 
Weight loss
Warm sweaty hands
Fine hand tremor
Tachycardia, AF
Bouncing pulse - wide pulse pressure
Proximal myopathy
Lid lag 
Staring eyes
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25
Q

LPS is 90% skeletal muscle and what percentage smooth muscle?

A

10% - supplied by sympathetic NS - overstimulation leads to staring eyes and lid lag

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26
Q

Is toxic multinodular goitre autoimmune?

A

No, so no exophthalmos or pretibial myxoedema

27
Q

What is a toxic adenoma?

A

A single adenoma in they thyroid that produces thyroxine autonomously

28
Q

Are thyroid cancers common?

A

No - they account for less than 1% of all cancers in UK

29
Q

Do thyroid cancers cause a metabolic disturbance?

A

No - non functional ‘cold’ nodule

30
Q

How can thyroid nodules be assessed?

A

Fine needle aspiration- but most are not 100% accurate so information has to be taken in conjunction with the history and examination

31
Q

If there is diagnostic doubt about the thyroid nodule after FNA, what can be done?

A

Hemithyroidectomy

32
Q

Why are lumpectomies not done on the thyroid?

A

If it is a malignant nodule this will not give adequate margins on the mass and it would make further surgery difficult due to scarring and put the recurrent laryngeal nerve at unacceptably high risk

33
Q

What types of malignant thyroid neoplasms are there?

A

Papillary adenocarcinoma
Follicular carcinoma
Medullary carcinoma
Anaplastic carcinoma

34
Q

What is the most common type of malignant thyroid neoplasm?

A

Papillary adenocarcinoma (70%)

35
Q

In terms of thyroid cancer, DNA mutations can turn proto-oncogenes (promote cell growth and proliferation) into what?

A

Ocogenes- proteins forcing cell to always be in on position - creating tumour

36
Q

In terms of thyroid cancer, DNA mutations can turn off tumour…

A

suppressor genes - cells dividing uncontrollably continue unchecked

37
Q

Papillary adenocarcinoma is associated with what?

A

RET and BRAF proto-oncogene mutations

Exposure to ionising radiation of neck during childhood

38
Q

Follicular carcinomas are the second most common from of thyroid cancer. True or false?

A

True

39
Q

Follicular carcinomas are associated with countries that have…

A

Low iodine diets

40
Q

In follicular carcinoma that tumour grows and breaks through the thyroid’s fibrous capsule. This means…

A

It can invade nearby blood vessels and metastasise to bones and brain in particular.

Don’t typically invade nearby lymph nodes

41
Q

Medullary carcinomas (5%) arise from what?

A

Calcitonin regulating c cells

42
Q

Where is the highest concentration of c cells?

A

Upper third of thyroid medulla

  • so this is where medullary carcinomas are likely to originate
43
Q

What causes medullary carcinomas?

A

Spontaneous mutation of the RET oncogene - causing single carcinoma in one lobe of thyroid

Part of inherited mutation e.g in familial medullary inherited carcinoma - may be multiple carcinomas across both lobes.
OR associated with the inherited condition: multiple endocrine neoplasia (MEN) type 2a or 2b

  • screening of other organs involved in MEN syndromes is required
44
Q

Under the microscope, medullary carcinomas are made up of what shaped cells?

A

Spindle shaped - long and skinny

45
Q

In medullary carcinoma, the c cells make excessive calcitonin, which can…

A

Deposit between c cells - clumps of protein cause fibrous deposits called amyloid around c cells

46
Q

In medullary carcinoma, c cells can produce other hormones (not just calcitonin), such as…

A

Seratonin

Vasoactive intestinal peptide

47
Q

Anaplastic carcinoma is typically seen in who?

A

Older patients

48
Q

In anaplastic carcinoma, do the cells look like normal thyroid cells?

A

No

Contain pleomorphic giant cells

49
Q

Which thyroid cancer is the most aggressive?

A

Anaplastic carcinoma

50
Q

Do anaplastic carcinomas often grow beyond the thyroid capsule?

A

Yes - and invade nearby structures

51
Q

What are the first signs of thyroid cancer?

A

Solitary painless nodule in thyroid gland
Hard and immovable
Horseness and dysphagia if invade larynx, oesophagus
No signs of hyper or hypothyroidism

52
Q

What signs could indicate medullary thyroid carcinoma?

A

Diarrhoea (vasoactive intestinal peptide)

Flushing of skin (serotonin)

53
Q

How are thyroid cancers diagnosed?

A

Ultrasound to identify nodule
TFTs , calcitonin
Radioiodine scan
Fine needle aspiration - identify type of tumour

54
Q

Who does papillary adenocarcinoma typically affect?

A

Young females

55
Q

How are papillary, follicular and medullary carcinomas managed?

A

Total thyroidectomy

Followed by radio iodine therapy for papillary and follicular carcinoma

56
Q

Is anaplastic disease normally too advanced for curative surgery?

A

Yes

57
Q

How are non neoplastic nodules managed?

A

Can be managed conservatively unless diagnostic uncertainty

Surgery - for compressive symptoms, cosmesis or patient preference. Should aim to restrict surgery to hemithyroidectomy due to the increased morbidity from a total thyroidectomy and the need for lifelong thyroxine replacement

58
Q

What benign thyroid neoplasms can occur?

A

Adenoma - mainly follicular

59
Q

How are adenomas treated?

A

Require no further treatment after diagnostic hemithyroidectomy

60
Q

What non neoplastic nodules are there?

A

Single nodule - colloid or cystic
Multinodular goitre - these are common and if they show typical features on USS do not necessarily require FNA (but any dominant nodule should have FNA)

61
Q

Is FNA reliable at differentiating a follicular carcinoma from a follicular adenoma?

A

No - a hemithyroidectomy should be carried out for definitive histology

62
Q

What complications can occur due to thyroid surgery?

A

Post op haemorrhage
Airway obstruction - secondary to haemorrhage or bilateral vocal cord palsy
Vocal cord palsy
Hypocalcaemia - if parathyroid glands removed

63
Q

What signs and symptoms are associated with hypocalcaemia?

A

CATs go numb

Convulsions
Arrhythmias
Tetany
and numbness in hands, feet and around mouth (also tingling, pins and needles sensation)

Tendon reflexes hyperactive
Trousseau sign - carpal spasm on inflation of BP cuff
Chvostek sign - facial spasm on tapping inferior cheek

Reduced calcium lowers the threshold for depolarisation (calcium blocks sodium channels - inhibiting depolarisation of nerve and muscle fibres)
Tetany

64
Q

What ECG changes occur due to hypocalcaemia?

A

QT prolongation

At risk of Torsades de pointes - type of ventricular tachycardia

ENT (Throat) (20 decks)

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