Hyperthyroidism

Clinical manifestations

• Symptoms
  • Anxiety
  • Tremor
  • Palpitations
  • Heat intolerance
  • Increased sweating
  • Weight loss
  • Diarrhoea
  • Menorrhagia
  • Dyspnoea
• Signs
  • Flushed
  • Tremor
  • Pulse – tachycardia, may be in atrial fibrillation
  • Lid retraction
  • Lid lag
  • Graves’ ophthalmopathy
    • Exophthalmos
    • Periorbital, conjunctival oedema
    • Complex ophthalmoplegia
  • Goitre
    • Tender / non-tender
    • Multi-nodular goitre
    • Single toxic adenoma
  • Proximal myopathy
  • Thyrocardiac disease
    • Displaced apex beat
    • Pulmonary oedema
  • Pretibial myxoedema (Graves’ disease only)

Differential diagnosis

• Inflammatory
  • Graves’ disease
  • Hashimoto’s thyroiditis (initial phase – Hashitoxicosis)
  • de Quervain’s thyroiditis (associated with coxsackie virus infection)
  • Riedel’s thyroiditis
  • Post-partum thyroiditis
• Neoplastic
  • Toxic adenoma
  • Multinodular goitre
  • Thyroid carcinoma
  • TSH-secreting adenoma
• Drugs
  • Iodine-induced hyperthyroidism (amiodarone)
  • Over-replacement of levothyroxine
  • Lithium
  • Interferon-α

Investigations

• Thyroid screen: thyroid stimulating hormone (low), free T4 (high), free T3 (high)
• Thyroid-stimulating hormone (TSH) receptor antibodies (TRAb)
• Radioactive iodine uptake scan
  • Multiple areas of increased uptake (MNG)
  • Single area of increased uptake (toxic adenoma)
  • Diffuse increased uptake (Graves’)
  • Cold nodule (thyroid carcinoma)

Management

• Multidisciplinary team approach
• Patient education
• Smoking cessation (worsens Graves’ ophthalmopathy)
• β blockade for tachycardia and palpitations (propranolol)
• Thionamides
  • Carbimazole (first-line
  • Propylthiouracil (preferred during pregnancy)
  • Risk of agranulocytosis
  • Monitor TFTs every 4-6 weeks
  • Suppressed TSH after 18 months predicts long-term treatment failure
• Radioiodine ablation
  • Oral solition of Na¹³¹I, which is rapidly concentrated in thyroid disuse
  • Causes gland destruction and ablation over 6 – 18 weeks
  • Can cause worsening of Graves’ ophthalmopathy
  • Patients must avoid contact with children and pregnant women for two weeks
• Surgery
  • Thyroidectomy with subsequent levothyroxine replacement