Hyperthyroidism

Question 1

What are causes of thyrotoxicosis?

Answer 1

Grave’s disease

Multi-nodular goitre

• Autonomous multiple thyroid nodules
• Uncertain pathogenesis, won’t remit (won’t go away)
• Next most common cause

Solitary toxic nodule

• Solitary benign adenoma
• TSH receptor activating mutation

Drug

• Interferon (used for hep c)
• Amiodarone (used for arrhythmia)

Question 2

What is Graves’ disease?

Answer 2

Antibody stimulation of TSH-receptor - ‘molecular mimicry’
Autoimmune mechanism, may remit
Commonest cause - especially in younger population

Question 3

What clinical features are due to Grave’s?

Answer 3

Exophthalmos (bulging of the eye anteriorly)
Ophthalmoplegia (paralysis or weakness of the eye muscles)
Pretibial myxoedema
Thyroid acropachy

Question 4

Symptoms of hyperthyroidism?

Answer 4

Weight loss (but still have a good appetite)
Tachycardia = with palpitations, AF
Sweating, heat intolerance
Irritability, mood swings
Frequent bowel action
Goitre
Eye signs: lid retraction
Thyroid eye disease:
- Exophthalmos (proptosis) - globe of eye protrudes
- Chemosis (conjunctival oedema), peri-orbital oedema

Question 5

What is eye thyroid disease?

Answer 5

Risks: intraocular pressure -> optic nerve damage exposure and corneal ulceration (due to eyes not closing)
- Can cause blindness
Treatment:
- Steroids, immunosuppression surgical decompression, radiotherapy

Question 6

What are treatment options for thyrotoxicosis?

Answer 6

Beta-adrenergic blockers - used for symptoms e.g. for heart rate and tremor
Antithyroid drugs (ATD)
- Carbimazole (methimazole)
- Propylthiouracil
Radioactive iodine
Surgery - sub-total, near-total thyroidectomy

Question 7

What are the anti-thyroid drugs used?

Answer 7

Carbimazole (methimazole in Europe and USA)
- Single daily doses OK
Propylthriouracil (PTU)
- Shorter half-life, 3x daily doses (150mg = 40mg CBZ)

Most UK patients get initially 6-24 months
- Remission after stopping: 50-60% at 1 year, 40% at 10 years

Question 8

What are the side effects of carbimazole?

Answer 8

Rash, itching (3-5%)
Arthralgia (joint pain)
Nausea, vomiting
Mild leucopenia
Agranulocytosis - NO production of neutrophils:
- 0.1-0.5% risk of significant infection
- Screening not normally done in UK
- Written warning leaflets advised
- Hospitalisation, antibiotics

Question 9

How does radioactive iodine work?

Answer 9

Emits beta and gamma - release of radiation destroys the tissue over a period of 6-18 weeks
Comes as either capsule or liquid format

Damages/kills thyroid follicular cells -> puts patients at risk of HYPOthyroidism (inevitable)

Question 10

What should anti-thyroid pretreatment be given?

Answer 10

To prevent thyroid crisis

Should stop 5-7 days before dose

Question 11

How should worsening of eye disease due to radio iodine be managed?

Answer 11

Especially occurs in smokers

Reduced/prevented by prednisolone

Question 12

What is involved in a thyroidectomy?

Answer 12

Near-total thyroidectomy

• Remnant tissue <2g - so have HYPOthyroidism after
• Patient takes T4 post-op
• Relapse rate <2%

May be recommended for patients with a large goitre or severs hyperthyroidism - patient preference also taken into account

Question 13

What complications can arise in a thyroidectomy?

Answer 13

Operator-dependant, experience-dependent (prefer > 20 cases/year)
Should be low for 1st operation:
- Permanent parathyroid damage 2-4%
- (Recurrent laryngeal nerve) Vocal cord paralysis <1%
- Bleeding <2%
- Keloid scars

Question 14

How does Post Partum Thyroiditis (PPT) present?

Answer 14

Symptoms often less severe (weight loss, palpitations, heat intolerance, anxiety)

Tremor, tachycardia, warm moist skin, muscle weakness, lid retraction, lid lag

Question 15

Thyroid function tests in Grave’s vs PPT?

Answer 15

Grave’s: fT3 increased to a greater degree than fT4 (TSH receptor antibodies)
PPT: fT4 increased to a greater degree tab fT3 (thyroid peroxidase autoantibodies)