Endo - Hyperthyroidism Flashcards

1
Q

What 2 ways does TSH cause and increase in thyroid hormone

A

Stimulates thyroxine production

Stimulates proteolytic enzymes to eat away colloid and release bound thyroxin into circulation

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2
Q

What regulates thyroid production

A

Negative feedback of T3 and T4 on the pituitary and the hypothalamus

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3
Q

What happens in primary hypothyroidism?

A

Immune system makes anti-thyroid antibodies therefore reduces the thyroid gland output

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4
Q

What happens in Grave’s disease?

A

Autoimmune condition whereby antibodies bind to TSH receptors and cause hyperthyroidism

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5
Q

What are the symptoms of Grave’s disease

A
Sweating
Flushing
Palpable lymph nodes
Muscle wasting
Shortness of breath
Breast enlargement/ gynaecomastia
Weight loss
Heat intolerance
Tachycardia
Pretibial myxoedema
Smooth diffuse goitre 
Tremor
Irritability
Increased appetite
Exophthalmos 
Insomnia
Diarrhoea
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6
Q

What causes exophthalmos

A

Separate autoantibodies bind to the muscles behind the eye

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7
Q

What causes an increase in heart rate and palpitations?

A

Increased thyroid hormone to increase sensitivity to adrenaline

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8
Q

What causes an increase in body temperature?

A

Increase in BMR

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9
Q

What causes pretibial myxoedema

A

Third antibody binds to the front of the tibia

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10
Q

How do we treat pretibial myxoedema

A

Topical steroids/ local injection to reduce inflammation

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11
Q

What does myxoedema usually refer to

A

Primary hypothyroidism

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12
Q

What is pretibial myxoedema?

A

Non pitting swelling that occurs in the tibial soft tissue of Grave’s disease patients

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13
Q

Describe the goitre seen in Grave’s

A

Smooth diffuse goitre that is uniform on both sides

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14
Q

How do we visualise the goitre in Grave’s

A

Radioactive iodine

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15
Q

What is Plummer’s disease?

A

Toxic nodular goitres which secrete T4

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16
Q

Is Plummer’s autoimmune?

A

No

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17
Q

As a result of Plummer’s not being autoimmune, what do we not see compared to Grave’s?

A

We don’t see exophthalmos or pretibial myxoedema

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18
Q

Why does Plummer’s give us an uneven appearance of thyroid gland?

A

Because the normal thyroid gland shrinks as only the nodular hot thyroid secretes hormones

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19
Q

What can we do to treat Plummer’s?

A

Hot nodule can be physically removed or we can give radioiodine

20
Q

What are the effects of thyroxine?

A

Sensitises beta adrenoreceptors to ambient levels of adrenaline and noradrenaline

Apparent sympathetic activation

Tachycardia
Palpitations
Tremors in hands
Lid lag

21
Q

What is thyroid storm?

A

Medical emergency arising form untreated hyperthyroidism

22
Q

Why is thyroid storm an emergency?

A

50% mortality if left untreated - but is completely treatable

23
Q

What are the signs of thyroid storm?

A
Hyperpyrexia (>41)
Tachycardia (170+)/ arrhythmia 
Cardiac failure
Delirium/psychosis
Hepatocellular dysfunction; jaundice
24
Q

How do we treat thyroid storm?

A

Thyroidectomy - can change voice
Radioiodine -radioactive for 6 days
Drugs

25
Q

What are the 4 types of drugs we can use to treat hyperthyroidism?

A

Thionamides
Potassium iodide
Radioiodine
Beta blockers

26
Q

What is the purpose of thionamides, potassium iodide and radioiodine

A

Daily treatment to reduce thyroid hormone synthesis

27
Q

What is the purpose of beta blockers

A

Help with symptoms whilst treatment is waiting to kick in

28
Q

What are the 2 thionamides we can use

A

Propylthiouracil (PTU)

Carbimazole (CBZ)

29
Q

How do thionamides work?

A

Inhibit TPO therefore block T3/4 synthesis and secretion

30
Q

What is the biochemical effect of thionamides?

A

Hours

31
Q

What is the clinical effect of thionamides?

A

Weeks

32
Q

What can we give whilst waiting for thionamides to work

A

Beta blocker e.g. propranolol

33
Q

What are the side effects of thionamides

A

Agranulocytosis (neutrophils down) (rare)

Rashes (common)

34
Q

When should we aim to stop thionamide treatment?

A

18 months. -regular review needed

35
Q

What is the dose of KI we give with extreme hyperthyroidism

A

60mg x 3 daily

36
Q

When is KI usually given

A

Preparation for surgery

37
Q

How does KI work?

A

Wolk-Chaikoff effect

38
Q

When do we start KI relative to an operation?

A

10 days before the operation to reduce blood flow to the thyroid gland during the surgery

39
Q

What is in radioiodine capsules?

A

370 MBq (10mCi) of Iodine 131

40
Q

When do we not give radioiodine?

A

Pregnancy or children

41
Q

If we only want to use iodine for scanning, not treatment - what do we use?

A

99-Tc pertechnetate

42
Q

What happens in viral (de Quervain’s) thyroiditis?

A

Virus takes over thyroid cells therefore they don’t make thyroid hormone, but there is destruction of cells so all thyroxin release to cause hyperthyroidism

43
Q

What are the symptoms of de Quervains

A

Dysphagia
Painful neck
Pyrexia
Hyperthyroidism

44
Q

What happens after a month of hyperthyroidism?

De Quervains

A

No more thyroxine and no more production therefore we get hypothyroidism for another month

45
Q

How long does it take to recover from De Quervains

A

3 months

46
Q

What happens in postpartum thyroiditis?

A

Similar to de Quervains but there is no pain and it happens after pregnancy - immune system modulated during pregnancy