Hyperthyroidism

Question 1

What is the definition of hyperthyroidism?

Answer 1

Over activity of the thyroid

Question 2

What is the pathophysiology of hyperthyroidism?

Answer 2

• TRH (Thyroid releasing hormone) is produced in the hypothalamus
• = pituitary gland secretes thyroid stimulating hormone (TSH)
• = THS stimulates growth and activity of the thyroid follicular cells
• Inorganic iodine → T3 (active) and T4 (prohormone) is released
• More T4 is produced but converted in peripheral tissue
• T3 binds to specific nuclear receptors on target cells
• Primary: disease of the thyroid – more common
• Secondary: hypothalamic-pituitary disease

Question 3

What are the risk factors/aetiology of hyperthyroidism?

Answer 3

• Woman
• Commonly between the ages of 20-40
• Other autoimmune disorders
• Graves’ disease – most common cause, autoimmune. Serum IgG antibodies bind to TSH receptors in the thyroid and behave like TSH
• Toxic multinodular goitre
• Solitary toxic nodule/adenoma
• Acute thyroiditis: viral (de Quervains), autoimmune, post irradiation
• Gestational/postpartum/neonatal
• Drugs: amiodarone
• Tumours

Question 4

What are the signs/symptoms of hyperthyroidism?

Answer 4

• Weight loss
• Restlessness/mania/psychosis
• Itching
• Sweating/heat intolerance/vasodilated peripheries
• Tall
• Palpitations/tachycardia/AF
• Systolic hypertension
• Muscle weakness/proximal myopathy/proximal muscle wasting
• Vomiting/diarrhoea
• Oligomenorrhea – infrequent/light periods
• Loss of libido
• Goitre
• Exophthalmos (Graves only)
• Ophthalmoplegia (Graves only) – paralysis of muscles within/around the eye
• Lid lag and stare
• Conjunctival/preorbital oedema
• Onycholysis – painless separation of nail from nail bed
• Palmar erythema
• Graves dermopathy aka Pretibial myxoedema (Graves only)
• Thyroid acropachy – clubbing (Graves only)

Question 5

What diseases present similarly to hyperthyroidism?

Answer 5

• Anxiety

* Phaeochomocytoma

Question 6

What investigations are carried out when hyperthyroidism is suspected?

Answer 6

• TFTs – immunoasssays for free T4, T3 and TSH
• ECG
• Autoantibodies – most commonly seen in Graves
• Thyroid US
• CRP/ESR ↑

Question 7

What are the surgical treatments for hyperthyroidism?

Answer 7

• Thyroidectomy – if large goitre, persistent drug side effect, poor compliance, recurrent hyperthyroidism

Question 8

What are the pharmacological treatments for hyperthyroidism?

Answer 8

• Anti-thyroid drugs: Carbimazole/PTU
• Radioactive iodine – if large goitre, persistent drug side effect, poor compliance, recurrent hyperthyroidism
• Beta blockers – symptom control