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Endocrine System > Hyperthyroidism > Flashcards

Hyperthyroidism Flashcards

1
Q

What is hyperthyroidism?

A

Hyperthyroidism is where there is over-production of thyroid hormone by the thyroid gland. Thyrotoxicosis refers to an abnormal and excessive quantity of thyroid hormone in the body.

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2
Q

What is primary hyperthyroidism?

A

Primary Hyperthyroidism is due to thyroid pathology. It is the thyroid itself that is behaving abnormally and producing excessive thyroid hormone.

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3
Q

What is secondary hyperthyroidism?

A

Secondary hyperthyroidism is the condition where the thyroid is producing excessive thyroid hormone as a result of overstimulation by thyroid stimulating hormone. The pathology is in the hypothalamus or pituitary.

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4
Q

What is graves disease?

A

Grave’s Disease is an autoimmune condition where TSH receptor antibodies cause a primary hyperthyroidism. These TSH receptor antibodies are abnormal antibodies produced by the immune system that mimic TSH and stimulate the TSH receptors on the thyroid. This is the most common cause of hyperthyroidism.

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5
Q

What is a toxic multi nodular goiture?

A

Toxic Multinodular Goitre (also known as Plummer’s disease) is a condition where nodules develop on the thyroid gland that act independently of the normal feedback system and continuously produce excessive thyroid hormone.

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6
Q

What is exopthalmos?

A

Exopthalmos is the term used to describe bulging of eyeball out of the socket caused by Graves Disease. This is due to inflammation, swelling and hypertrophy of the tissue behind the eyeball that forces the eyeball forward.

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7
Q

Pretibial myxodema?

A

Pretibial Myxoedema is a dermatological condition where there are deposits of mucin under the skin on the anterior aspect of the leg (the pre-tibial area). This gives a discoloured, waxy, oedematous appearance to the skin over this area. It is specific to Grave’s disease and is a reaction to the TSH receptor antibodies.

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8
Q

Features of hyperthyroidism

A 
Anxiety and irritability
Sweating and heat intolerance
Tachycardia
Weight loss
Fatigue
Frequent loose stools
Sexual dysfunction
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9
Q

Graves disease

A
  • Anti-TSH receptor antibodies
  • Most common cause of hyperthyroidism (75%)
  • Diffuse goitre and thyroid eye signs
  • more common in women
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10
Q

Toxic multinodular goitre

A
  • Iodine deficiency
  • Compensatory TSH secretion
  • Nodular goitre formation
  • Nodules become TSH-independent and thyroid hormones
  • more common in >60yrs women
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11
Q

Graves features

A

These features all relate to the presence of TSH receptor antibodies.

Diffuse Goitre (without nodules)
Graves Eye Disease
Bilateral Exopthalmos
Pretibial Myxoedema

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12
Q

Toxic multinodular goitre features

A

Goitre with firm nodules
Most patients are aged over 50
Second most common cause of thyrotoxicosis (after Grave’s)

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13
Q

Toxic adenoma

A

Single autonomous functional nodule

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14
Q

How does a toxic multi nodular goitre form?

A

Iodine deficiency - is the cause of nodules forming as decreased T4, therefore excess TSH released by the pituitary therefore you get thyroid cell hyperplasia causing the nodules - that mutates the TSH receptor leading to them becoming autonomous

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15
Q

Thyroiditis

A
  • Inflammation of the thyroid gland
    starts with hyperthyroidism then goes on to hypothyroidism happens in hashimotos’ (autoimmune) and De Quervain’s thyroiditis (following infection)
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16
Q

Subclinical hyperthyroidism?

A

Normal T3/T4, low TSH

May be due to other causes normally graves or toxic

17
Q

Drugs effect on the thyroid?

A

Amiodarone can cause hyper and hypothyroidism

It has a high iodine content and is also toxic to the thyroid

18
Q

Secondary hyperthyroidism

A
  1. Pituitary adenoma
    - TSH secreting
  2. Ectopic tumour
    - hCG- secreting tumour (e.g. choriocarcinoma) - can mimic TSH
  3. Hyopthalamic tumur
    - excessive TRH secretion, very rare
19
Q

Risk factors for Hyperthyroidism

A
  • Female gender - Graves
  • FHx
  • Other autoimmune conditions e.g. T1DM
  • Smoking - graves eye disease
  • Trauma to the thyroid - including surgery
  • Drugs - amiodaerone
20
Q

De Quervain’s Thyroiditis

A

De Quervain’s Thyroiditis describes the presentation of a viral infection with fever, neck pain and tenderness, dysphagia and features of hyperthyroidism. There is a hyperthyroid phase followed by hypothyroid phase as the TSH level falls due to negative feedback. It is a self-limiting condition and supportive treatment with NSAIDs for pain and inflammation and beta blockers for symptomatic relief of hyperthyroidism is usually all that is necessary.

21
Q

Thyroid storm

A

Thyroid storm is a rare presentation of hyperthyroidism. It is also known as “thyrotoxic crisis”. It is a more severe presentation of hyperthyroidism with pyrexia, tachycardia and delirium. It requires admission for monitoring and is treated the same way as any other presentation of thyrotoxicosis, although they may need supportive care with fluid resuscitation, anti-arrhythmic medication and beta blockers.

22
Q

Hyperthyroidism management

A
  1. Carbimazole
  2. Propylthiouracil
  3. Radioactive iodine
  4. Beta blockers
  5. Surgery
23
Q

THYROIDISM mnemonic

A 
Tremor 
Heart rate increase 
Yawning 
Restless 
Oligomenorrhoea 
Irritability 
Diarrhoea 
Intolorance to heat 
Sweating 
Muscle wasting (weight loss)
24
Q

Carbimazole with hyperthyroidism

A

Carbimazole is the first line anti-thyroid drug. It is usually successful in treating patients with Grave’s Disease, leaving them with normal thyroid function after 4-8 weeks. Once the patient has normal thyroid hormone levels, they continue on maintenance carbimazole and either:

The dose is carefully titrated to maintain normal levels (known as “titration-block”)
The dose is sufficient to block all production and the patient takes levothyroxine titrated to effect (known as “block and replace”)
Complete remission and the ability to stop taking carbimazole is usually achieved within 18 months of treatment.

25
Q

Propylthiouracil and hyperthyroidism

A

Propylthiouracil is the second line anti-thyroid drug. It is used in a similar way to carbimazole. There is a small risk of severe hepatic reactions, including death, which is why carbimazole is preferred.

26
Q

Radioactive Iodine in hyperthyroidism

A

Treatment with radioactive iodine involves drinking a single dose of radioactive iodine. This is taken up by the thyroid gland and the emitted radiation destroys a proportion of the thyroid cells. This reduction in functioning cells results in a decrease of thyroid hormone production and thus remission from the hyperthyroidism. Remission can take 6 months and patients can be left hypothyroid afterwards and require levothyroxine replacement.

27
Q

Rules for patients that have had radioactive iodide treatment

A

There are strict rules where the patient:

Must not be pregnant and are not allowed to get pregnant within 6 months
Must avoid close contact with children and pregnant women for 3 weeks (depending on the dose)
Limit contact with anyone for several days after receiving the dose

28
Q

Beta blockers in hyperthyroidism

A

Beta blockers are used to block the adrenalin related symptoms of hyperthyroidism. Propranolol is a good choice because it non-selectively blocks adrenergic activity as opposed to more “selective” beta blockers the work only on the heart. They do not actually treat the underlying problem but control the symptoms whilst the definitive treatment takes time to work. They are particularly useful in patients with thyroid storm.

29
Q

Surgery in the treatment of hyperthyroidism

A

A definitive option is to surgically remove the whole thyroid or toxic nodules. This effectively stops the production of thyroid hormone, however the patient will be left hypothyroid post thyroidectomy and require levothyroxine replacement for life.

30
Q

Graves antibodies

A

Anti-TSH
Anti- TPO (70-80%) mostly
Anti-thyroglobulin

31
Q

Hashimoto’s antibodies

A

Anti TPO mostly in Hashimoto’s

32
Q

Investigations

A

TFTs first line then anti-TSH antibodies tested

33
Q

Investigations to consider

A
  • Ultrasound = if thyrotoxic with palpable thyroid nodule
  • Technetium radionuclide scan = performed if anti-TSH antibodies are negative
  • Glucose = hyperthyroidism is associated with hyperglycaemia
  • ECG = hyperthyroidism is associated with AF

Endocrine System (10 decks)

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