Autoimmune condition, TSH receptor antibodies are causing primary hyperthyroidism

Most common cause of thyrotoxicosis

Typically seen in women aged 30-50 years

Features

Typical features of thyrotoxicosis

specific signs seen in Graves' but not in other causes of thyrotoxicosis:

• DIffuse goitre, without nodules
• eye signs (30% of patients)
  • exophthalmos > 3mm - This is due to inflammation, swelling and hypertrophy of the tissue behind the eyeball that forces the eyeball forward.
  • ophthalmoplegia
• pretibial myxoedema - 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.
• thyroid acropachy, a triad of:
  • digital clubbing
  • soft tissue swelling of the hands and feet
  • periosteal new bone formation

Investigations

Autoantibodies

• TSH receptor stimulating antibodies (90%)
• anti-thyroid peroxidase antibodies (75%)

Thyroid scintigraphy - nuclear medicine procedure that produces a visual display of functional thyroid tissue based on the selective uptake of various radionuclides by thyroid tissue.

• Findings: diffuse, homogenous, increased uptake of radioactive iodine

Management