How can I differentiate between Graves' disease and other causes of hyperthyroidism in a primary care setting?

In a primary care setting, differentiating between Graves' disease and other causes of hyperthyroidism in adults primarily involves specific blood tests and considering imaging studies, often in consultation with or leading to referral to an endocrinologist ¹,².

The key step is to measure TSH receptor antibodies (TRAbs) ². A positive TRAbs result confirms Graves' disease ².

If TRAbs are negative, a technetium scan of the thyroid gland should be considered to help distinguish other causes of hyperthyroidism ². This scan typically shows a diffuse pattern of uptake in Graves' disease, one or more 'hot' nodules in toxic nodular hyperthyroidism, and reduced or absent uptake in all types of thyroiditis ¹.

A thyroid ultrasound scan with Doppler may also be used ¹. However, for adults with thyrotoxicosis, ultrasound is generally only considered if there is a palpable thyroid nodule ². For children and young people, ultrasound is offered if a palpable thyroid nodule is present or if the cause remains unclear following thyroid autoantibody testing and technetium scanning ².

Following a confirmed diagnosis of overt hyperthyroidism via thyroid function tests, it is important to arrange referral or discuss with an endocrinologist the need for specialist investigations and management for all other people with new-onset hyperthyroidism ¹.