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BRS Year 2 > Hyperthyroidism > Flashcards

Hyperthyroidism Flashcards

1
Q

What does TSH do?

A

Activates uptake of iodine into the thyroid follicular cell which eventually leads to formation of thyroxine

Activates proteolytic enzyme

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2
Q

How much thyroxine do we store?

A

Enough for one month

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3
Q

What enzyme allows release of thyroxine from the thyroid follicular cell? How does it do this?

A

Proteolytic enzyme- makes a hole in the cell

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4
Q

How does the negative feedback loop for thyroxine work?

A

T3 and T4 have negative feedback on the pituitary AND on the hypothalamus

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5
Q

What will TSH levels be in someone with primary hypothyroidism where the thyroid gland is destroyed?

A

High TSH

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6
Q

What does thyroxine do?

A

Increases a lot of metabolic processes

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7
Q

What is Graves disease?

A

An autoimmune condition where antibodies bind to and stimulate the TSH receptor in the thyroid causing a smooth goitre and hyperthyroidism

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8
Q

What happens to the thyroid in Graves disease?

A

Smooth goitre

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9
Q

How does Graves disease present?

A 
CNS: Nervousness, excitability, restlessness, emotional instability, insomnia
Exophthalmos
Sweatiness
Mostly female and young
Weight loss with increased appetite 
High pulse
Oligo/amenorrhea
Swollen ankles and shins (pretibial myxoedema) 
Tremor
Diarrhoea
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10
Q

What is Plummer’s disease? What type of condition is it? How does it differ from Grave’s symptomatically?

A

Benign toxic nodular goitre of thyroid (NOT autoimmune) that causes hyperthyroidism
NO pre-tibial myxoedema or exophthalmos

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11
Q

What are TSH, T3, T4 levels in someone with Plummer’s?

A

High T3 and T4

No TSH

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12
Q

How do we differentiate Plummer’s vs Grave’s?

A

In Plummer’s theres one large benign growth and the rest of the thyroid shrinks
In Graves the whole gland is enlarged

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13
Q

What is any non Grave’s hyperthyroidism classified as?

A

Plummer’s

aka toxic multi-nodular goitre or hot nodule

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14
Q

How does thyroxine effect the sympathetic nervous system? How does this present?

A

T3 makes beta receptors more sensitive to adrenaline /noradrenaline (doesn’t bind but makes downstream cascade faster).
This leads to sympathetic activation
Tachycardia, palpitations, tremor in hands (beta receptors in skeletal muscles), lid lag

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15
Q

What is lid lag and how do you test it?

A

Ask them to follow your finger take it really high up, to mid level and low down and if they have hyperthyroidism their eyelids will lag and stay up slightly too long due to excess adrenaline

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16
Q

What symptoms do you need to ask about when you suspect hyperthyroidism

A 
Weight loss despite increased appetite
Breathlessness
Palpitations,tachycardia
Sweating
Heat intolerance
Diarrhoea
Lid lag and other sympathetic features
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17
Q

What is thyroid storm?

A

Medical emergency- 50% mortality untreated

Untreated hyperthyroidism= lots of excess thyroxine

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18
Q

What is treatment for a thyroid storm?

A

Urgent in hospital treatment

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19
Q

What are options for treating hyperthyroidism?

A

Surgery (thyroidectomy)
Radioiodine
Drugs

20
Q

What drugs can be used for hyperthyroidism?

A

Thionamides- propylthiouracil and carbimazole
Potassium iodide
Radioiodine
Beta blockers (only helps with symptoms -fast acting)

21
Q

How do thionamides work?

A

Inhibit thyroid peroxidase so reduce T3/T4 synthesis- takes weeks to show on blood test, so give beta blockers for first few weeks

22
Q

What are side effects of thionamides?

A

Agranulocytosis- reduction of neutrophils (get sore throats)- reversible on withdrawal of drug
Rashes

23
Q

When is iodine used to treat hyperthyroidism?

A

Preparing them for surgery (quick action)

If in a thyroid storm

24
Q

Why is iodine not an ideal drug?

A

Its not for long term- only used for 10 days

25
Q

Why is iodine used in hyperthyroidism before surgery?

A

Reduces vascularity and size of gland within 10-14 days (less bleeding)
Reduces hyperthyroid symptoms within 1-2 days

26
Q

What is the main risk with thyroid surgery?

A

Cutting of recurrent laryngeal nerve which alters voice
Risk of losing parathyroid glands
Scar
Anaesthetic

27
Q

How is radioiodine taken and what precautions must you take?

A

Swallow a capsule of 370 MBq

Stay away from pregnant people for a few days as you emit radiation

28
Q

How does viral (de Quervain’s) thyroiditis present?

A

Painful dysphagia
Hyperthyroidism
Pyrexia
Thyroid inflammation

29
Q

How is viral thyroiditis diagnosed?

A

They have no iodine uptake at all on thyroid scintigraphy (cells are too inflamed), this wouldn’t happen in Graves or Plummers

30
Q

What happens long term in viral thyroiditis?

A

After a month of hyperthyroidism (all stored thyroxine is released) there is hypothyroidism as no new thyroxine has been synthesised, eventually even after that they will go back to normal (after 3 months- euthyroid)

31
Q

In grave’s disease, where can antibodies also have an effect (apart from thyroid)?

A

Other Abs bind to muscles behind the eye and cause exophthalmos
Other Abs cause pretibial myxoedema

32
Q

What is pretibial myxoedema?

A

Non-pitting (pitting is to do with cardiac failure and fluid build up) swelling that occurs on shins of patients with Grave’s disease- growth of soft tissue

33
Q

How does graves disease appear on a radioiodine thyroid scan?

A

Uniform uptake of radioiodine due to presence of TSH receptors on entire gland

34
Q

What imaging can we use to see the thyroid gland?

A

Thyroid scintigraphy

35
Q

How does plummer’s appear on a Thyroid scintigraphy ?

A

A large mass (hot nodule)- doesn’t take up all the tracer as it’s not very active

36
Q

What are symptoms of a thyroid storm?

A 
Hyperpyrexia > 41oC
accelerated tachycardia / arrhythmia
cardiac failure
delirium / frank psychosis
hepatocellular dysfunction; jaundice
37
Q

What do thioamides treat?

A

Grave’s

Toxic thyroid nodule/ toxic multinodular goitre

38
Q

Give an example of a beta blocker and it’s impact

A

Propranolol

Rapidly reduces tremor and tachycardia

39
Q

For a patient taking thionamides, what are aims of follow up?

A

Aim to stop antithyroid drug treatment after 18 months

Review patient periodically including thyroid function tests for remission/relapse

40
Q

What is the role of beta blockers in thyrotoxicosis?

A

Several weeks for anti-thyroid drugs to work
Non-selective (ie B1 and B2) beta blockers are given e.g. propranolol to reduce symptoms (reduce tremor, slow HR, less anxiety)

41
Q

What is the mechanism of potassium iodide?

A

Inhibits iodination of thyroglobulin
Inhibits hydrogen peroxidase generation and thyroperoxidase

Wolff-chaikoff effect - inhibition of thyroid hormone synthesis and secretion- presumed autoregulatory affect

42
Q

What is the impact on the thyroid gland before and after treatment with thiouracil and thiouracil plus iodine?

A

Hyperplastic thyroid: Gland enlarged, tears and bleeds easily. Acinar hyperplasia and loss of colloid

After thiouracil: Gland mass increases, tear and bleeds more easily. Increased acinar cell hyperplasia, complete loss of colloid

After thiouracil and iodine: Gland shrinks, pale and firm, does not tear or bleed easily. Involution of acinar epithelium, storage of iodine- poor colloid

43
Q

How does the thyroid gland appear in viral thyroiditis?

A

Visibly enlarged more on one side

44
Q

What is the mechanism of viral thyroiditis?

A

Virus attacks thyroid gland causing pain and tenderness
Thyroid stops making thyroxine and makes viruses instead
No iodine uptake

45
Q

Describe the course of viral thyroiditis

A 
Neck becomes painful;
All stored thyroxine released
Free T4 levels rise
YSH levels drop
1 month HYPERthyroidism
BUT no new thyroxine being made

FT4 slowly falls
Patient gets HYPOthyroidism
After 3 months, theres slow recovery

BRS Year 2 (110 decks)

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