What pathologic change is associated with Graves disease?

Graves disease is an autoimmune disorder characterized by hyperthyroidism, and a key pathologic change associated with this condition is the presence of high levels of circulating thyroid-stimulating immunoglobulins (TSIs). These immunoglobulins mimic the action of thyroid-stimulating hormone (TSH) by binding to and activating the TSH receptors on thyroid cells. This activation leads to increased synthesis and release of thyroid hormones, particularly thyroxine (T4) and triiodothyronine (T3), resulting in the symptoms of hyperthyroidism.

In Graves disease, the high levels of these immunoglobulins, rather than TSH itself, are the driving force behind the overactivity of the thyroid gland. As a result, TSH levels in the serum tend to be low due to negative feedback mechanisms; increased thyroid hormone levels downregulate TSH release from the pituitary gland.

This complex hormonal interaction and the autoimmune nature of the disease underscore the importance of recognizing high circulating levels of TSIs as a hallmark of Graves disease.