Hyperthyroidism

Question 1

What is the most common cause of hyperthyroidism in the western world?

Answer 1

Grave’s disease- 80-90% of cases

Question 2

What is the demographic for Graves disease?

Answer 2

• Most cases present in ages 30-60 year olds
• Women are 10 x more likely than men (in uk women is 20 in 1000, men is 2 in 1000)

Question 3

What is Grave’s disease?

Answer 3

• An autoimmune condition with a genetic predisposition. Where the body produces thyroid-stimulating antibodies. These antibodies mimic TSH and so bind to TSH receptors in the thyroid to increase production of the thyroid hormone.
• mostly affects middle-aged/young women
• often runs in families
• smoking can increase risk

Question 4

Aside from Grave’s disease, what else can cause hyperthyroidism?

Answer 4

• Toxic-nodular goitre- this is when new follicles are formed which develop into nodules (more and increased size). These nodules can also secrete thyroid hormone leading to overproduction. This is also known as Plummer’s disease
• Thyroid adenomas- These are benign tumours (nodules) as result of overgrowth of normal thyroid tissue, that will also secrete thyroid hormone, leading to overproduction.

Question 5

What are the symptoms of hyperthyroidism?

Answer 5

Higher metabolic rate;
- palpitations
- sweating
- tremor
- anxiety
- diarrhoea
- inability to tolerate heat
- weight loss
- goitre
- eye problems- expo-thalamus, swelling, irritation, lid retraction, double vision
- tachycardia
- fatigue
- loose stools
- sexual dysfunction

Question 6

What is exophthalmos?

Answer 6

The bulging of eyes- precision anteriorly from the face

Question 7

What levels of T3,T4 and TSH are indicative of hyperthyroidism?

Answer 7

• High free T3 and T4
• Low TSH levels

due to too much t3 and t4 being produced in the thyroid, which sends negative feedback to the anterior pituitary, causing it to cut off TSH production.

Question 8

What is thyrotoxicosis?

Answer 8

Too much circulation thyroid hormone in the body

Question 9

What is the difference between primary and secondary hyperthyroidism?

Answer 9

• Primary: The thyroid itself is producing too much thyroid hormone
• Secondary: The thyroid is producing excess thyroid hormone as a result of overstimulation by TSH

Question 10

What is De Quervain’s thyroiditis?

Answer 10

A painful swelling of the thyroid that is caused by a viral infection such as flu or mumps.
- It’s most commonly seen in women aged 20 to 50
- symptoms include a high temperature, fever, neck pain, tenderness, dysphagia
- symptoms will go down after a few days but can give NSAIDs and beta-blockers if required.

Question 11

What is thyroid storm/thyrotoxic crisis?

Answer 11

• When a poorly controlled or undiagnosed over-active thyroid can lead to fatal condition. Or can be triggered by a punch to the thyroid, pregnancy, an infection
• symptoms include- fever, delirium, tachycardia, high blood pressure, jaundice, loss of consciousness
• is a medical emergency! would be admitted

Question 12

What can be prescribed to relieve symptoms of hyperthyroidism and why?

Answer 12

Hyperthyroidism leads to up-regulation of the beta-adrenergic receptors causing adrenaline-related symptoms
- Can give a non-selective beta blocker such as propranolol to block these symptoms (tremor, palpitations, tachycardia, stress etc)
- Must be non-selective as a beta-1 antagonists are cardio-selective ( e.g. Bisoprolol) and so would only help with palpitations/heart symptoms (and not sweating, tremor etc)

Question 13

What is the first line treatment for hyperthyroidism?

Answer 13

• Carbimazole ( a Thioureylene)
  Usually is given a higher dose for 4-8 weeks and then either titrated to maintain ‘normal’ levels (titrated regimen) OR used to block all hormone and replace with levothyroxine ( known as the block and replace strategy) usually only needed for 12-18 months
• If carbimazole is not tolerated, propylthiouracil may be given. also, if the patient is trying to get pregnant in the near future or has a history of pancreatitis.
  Carbimazole is preferred overall though due to the risk of hepatic failure.

Question 14

What is the most important counselling point with carbimazole and polythiouracil in terms of side effects?

Answer 14

• In 0.3% of cases, can cause ‘Agranulocytosis’, which causes a major depletion in white blood cell (neutrophils) count and therefore his susceptibility to infection.
  This can be fatal and so the patients are told to report, symptoms of sore throat, mouth ulcers, fever, malaise, bruising or bleeding.
  if a patient develops agranulocytosis, the anti-thyroid drugs (carbimazole and polythiouracil) should be stopped and NOT restarted- refer to a specialist

Question 15

Why is contraception an important counselling point in patients taking carbimazole?

Answer 15

Because women should not become pregnant while taking carbimazole due to it causing congenital malformations.
- women on carbimazole are advised strong contraception such as an IUD.

Question 16

Aside from drugs (carbimazole, polythiouracil), what other treatments are available for hyperthyroidism?

Answer 16

• Surgery- A thyroidectomy to remove the thyroid gland. Most used if have a large goitre or drug therapy fails. if al the gland is removed, patient will have to take levothyroxine for life
• Radiotherapy- using Radioiodine (I-131), it emits beta particles and gamma rays to Kill thyroid cells, to reduce hormone production. Is given via a drink. this can take a few weeks to have an effect but online treatment is required. Patients must stay away from children and pregnant women for 3 weeks and avoid getting pregnant for 6 weeks or fathering a child for 4 months.

Question 17

What drug can induce thyroid dysfunction?

Answer 17

Amiodarone, which is used for cardiac arrhythmia can cause hypo or hyper thyroidism as it contains 39% iodine by weight. Patients starting Amiodarone should have baseline TFTs before starting treatment and then every 6 months thereafter.