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BRS 1b > 3.6 Hyperthyroidism > Flashcards

3.6 Hyperthyroidism Flashcards

1
Q

When are the two important functions of TSH?

A

activates iodide uptake

activates the release of T3 and T4 into the blood stream

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2
Q

What does thyroxine do? (1)

A

Increase basal metabolic rate

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3
Q

What is TRH?

A

Thyrotropin releasing hormone

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4
Q

Where does TRH come from?

A

hypothalamus

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5
Q

What is the action of TRH?

A

TRH acts on thyrotrophs in the anterior pituitary, to secrete TSH

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6
Q

What does T3 and T4 feedback to?

A

T3 and T4 feedback negatively to the anterior pituitary and the hypothalamus

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7
Q

What will the TSH levels of a patient with primary hypothyroidism?

A

high

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8
Q

How do we adjust the dose of levothyroxine

A

Increase dose until TSH falls to normal

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9
Q

What is Graves’ disease?

A

Autoimmune disease where antibodies bind to and stimulate TSH receptors in the thyroid, resulting in hyperthyroidism

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10
Q

What are some of the observable features of graves’ disease?

A

breast enlargement
facial flashing
goitre (swelling of neck –> due to swelling of thyroid gland)

shortness of breath
weight loss
muscle wasting –> causing muscle weakness
perspiration

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11
Q

What are some of the non - observable features of graves’ disease?

A

feeling hot
increased appetite
tachycardia

diarrhoea
insomnia
nervousness/excitability/emotional instability
oligomenorrhea or amenorrhea

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12
Q

What symptoms in graves disease are caused by other antibodies not affecting the thyroid?

A

other antibodies bind to muscles behind the eye (cause growth) and cause exophthalmos
other antibodies cause pretibial myxoedema

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13
Q

What is pretibial myxoedema?

A

The swelling that occurs (non-pitting) on the shins of patients with graves disease.
myxoedema–> swelling of LL
caused by hypertrophy

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14
Q

What is the difference between myxoedema and pretibial myxoedema?

A

myxoedema caused by hyperthyroidism

pretibial myxoedema caused by Grave’s disease

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15
Q

What would you see if do a radio-iodine uptake scan a patient with graves disease?

A

uniform radioiodine uptake and enlarged thyroid gland

very dark as very active

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16
Q

What is toxic nodular goitre?

A

benign adenoma that is overactive at making thyroxine

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17
Q

What is the difference between toxic nodular goitre and graves disease?

A 
toxic nodular goitre:
NOT autoimmune
NO pretibial myxoedema
NO exophthalmos
swelling on neck tends to be on one side
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18
Q

What would you see if do a radio-iodine uptake scan a patient with toxic nodular goitre?

A

lots of spill over, dark spot = ‘hot spot’ not uniform thyroid gland shape (as can be due to just hyperproliferation once cell thats secreting too much thyroxine, and rest of thyroid atrophys)

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19
Q

Why can hyperthyroidism be a medical emergency?

A

If hyperthyroidism gets extremely severe (high), the can have a thyroid storm.
Thyroid storm –> 50% mortality rate

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20
Q

What is the effect of thyroxine on the sympathetic nervous system?

A

sensitises beta adrenoreceptors to ambient levels of adrenaline and noradrenaline.
–> some symptoms similar to extra adrenaline (palpitations, tachycardia, tremor in hands, lid lag)

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21
Q
A

propanaol - beta blocker

22
Q

What is thyroid storm?

A

Hyperthyroidism
AND TWO OR MORE OF:
- hyperpyrexia >41 degrees
- accelerated tachycardia/arrythmia
- cardiac failure
- delirium/frank psychosis (brain affected)
- hepatocellular dysfunction; jaundice (liver affected)

23
Q

What are the treatment options for hyperthyroidism?

A

surgery
radioiodine
drugs

24
Q

What are the four classes of drugs used in the treatment of hyperthyroidism?

A
  1. Thionamides
  2. Potassium Iodide
  3. Radioiodine
  4. Beta-blockers
25
Q

What are the names of two thianomides used to treat hyperthyroidism?

A

propylthiouracil (PTU)

carbimazole (CBZ)

26
Q

What are the role of thianomides in the treatment of hyperthyroidism?

A

they are anti-thyroid drugs; block iodine uptake into iodide gland

27
Q

How can potassium iodide and radioiodine be used in the treatment of hyperthyroidism?

A

big dose, decreases thyroid function synthesis as a bit overloaded, reduces thyroid function for a few days (short acting)

28
Q

How are beta blockers used in the treatment of hyperthyroidism?

A

Used to reduce symptoms causes by extra adrenaline.

29
Q

What is the mechanism of thionamides?

A

inhibit thyroid peroxidase and hence T3/4 synthesis and secretion
biochemical effect: hours
clinical effect: 4-6 weeks because stores thyroxine had to be used up

30
Q

Why are beta blockers prescribed initially for patients with hyperthyroidism but then stopped after a few weeks?

A

Thionamides take a few weeks to work

BB provide symptom relief straight away then stopped when thionamides work

31
Q

What are some side effects of thionamides ?

A

rashes (common)

agranulocytosis (rare) - usually reduction in neutrophils and reversible on withdrawal of drug

32
Q

What is the follow up for treatment of hyperthyroidism?

A

usually aim to stop anti-thyroid drug treatment after 18 months (half then cured)
review patient periodically incl. thyroid function tests for remission/relapse

33
Q

When is potassium iodide used in the treatment of hyperthyroidism?

A
  • preparation of hyperthyroidism patients for surgery

- thyroid storm (thyrotoxic crisis)

34
Q

What dose of KI used in the treatment of hyperthyroidism?

A

30x average daily requirement daily

35
Q

What is the mechanism of KI, what is this effect known as?

A

–> inhibition of T3/4 synthesis and secretion

presumed auto-regulatory effect (WOLFF -CHAIKOFF effect)

36
Q

How long does it take for KI to start working in treatment of hyperthyroidism?

A

symptoms reduce in 1-2 days

37
Q

Why do surgeons like KI to be prescribed before surgery?

A

vascularity and size of gland reduce within 10 to 14 days

38
Q

How long does the effects of KI last?

A

about 10 days

39
Q

What are the risks of thyroid surgery? (4)

A

risk of voice change (ability to shout or sing)
risk of also losing parathyroid gland
scar
anaesthetic

40
Q

How is radioiodine used in the treatment of hyperthyroidism?

A

swallow capsule containing 370 MBq of isotope I 131

41
Q

What are the rules of using radioiodine in the treatment of hyperthyroidism, when should it not be used?

A

contraindicated in pregnancy
isolate for about 10 days (avoiding children and pregnant women)
radiation lasts about 6 weeks

42
Q

Is radioiodine treatment the same as what is used in scans?

A

Can be.

99-Tc (pertchnetate) is cheaper option can be used for scans only (not treatment)

43
Q

What is the name of the beta blocker used in hyperthyroid treatment?

A

propranolol

44
Q

What is viral thyroiditis?

A

Virus attacks thyroid gland, causing thyroid to stop making thyroxine and makes viruses instead.

45
Q

What are the symptoms of viral thyroiditis?

A 
painful dysphagia
hyperthyroidism
pyrexia
thyroid inflammation (visibly on one side)
pain radiating to ear
46
Q

How do we test for viral thyroiditis?

A

viral thyroiditis will have no iodine uptake (ZERO), because thyroid making virus

47
Q

Why does viral thyroiditis cause hyperthyroidism?

A

When virus attacks thyroid gland, all stored thyroxine leaks out.

48
Q

What does the progression of viral thyroiditis look like?

A

1 month hyperthyroidism (thyroxine stores released, free T4 levels rise)
1 month hypothyroidism –> when thyroxine stores run out
patient recovers from virus
normal thyroid function again

49
Q

How should we treat the thyroid symptoms of viral thyroiditis?

A

No nothing - thyroid function will return back to normal and prescribing something could alter that

50
Q

What is postpartum thyroiditis?

A

similar to viral thyroiditis but without neck pain and post partum (autoimmune)

51
Q

What are 4 causes of hyperthyroidism

A

Graves disease
Nodular thyroid disease
Viral thyroiditis
Postpartum thyroiditis

52
Q

What is the cause of postpartum thyroiditis?

A

immune system modulated during pregnancy

BRS 1b (25 decks)

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