Serial TSH-receptor antibody levels to guide the management of thyroid eye disease: the impact of smoking, immunosuppression, radio-iodine, and thyroidectomy.

The Thyrotropin receptor antibody (TRAb) is the main driver of Graves' disease (GD) and its most common extra-thyroidal manifestation: thyroid eye disease (TED). Though key to diagnosis, it has not been used routinely as a marker of disease activity or to guide treatment. Here we demonstrate, through a retrospective review of 105 patients with TED, that serial TRAb levels vary with time, correlate with disease activity and are affected by smoking and endocrine control. Such serial measurements can guide the modern management of thyroid eye disease, helping to prevent the more serious manifestations. We show that surgical thyroidectomy is associated with a reduction in antibody levels and a reduced rate of TED reactivation when compared to radio-iodine ablation where the stimulating antigen is not removed. This provides a molecular explanation for epidemiological studies showing radio-ablation being associated with an increased risk of orbitopathy. To demonstrate the effect of our clinical approach on a patient population, we then compared the incidence and severity of TED in a clinic in a period before and after the introduction of serial TRAb measurements. Despite an increase in disease incidence and severity at presentation over the two-decade study period, our approach saw a significant reduction in the need for surgical intervention for this orbital disorder.