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 NICE CKS,NICE NG145.
The key step is to measure TSH receptor antibodies (TRAbs) NICE NG145. A positive TRAbs result confirms Graves' disease NICE NG145.
If TRAbs are negative, a technetium scan of the thyroid gland should be considered to help distinguish other causes of hyperthyroidism NICE NG145. 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 NICE CKS.
A thyroid ultrasound scan with Doppler may also be used NICE CKS. However, for adults with thyrotoxicosis, ultrasound is generally only considered if there is a palpable thyroid nodule NICE NG145. 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 NICE NG145.
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 NICE CKS.