What condition is characterized by exophthalmos?

Exophthalmos, also known as proptosis, is the condition characterized by the abnormal protrusion of the eyeballs. This eye abnormality is most commonly associated with hyperthyroidism, particularly in the context of Graves' disease, an autoimmune disorder that leads to overactivity of the thyroid gland.

In hyperthyroidism, the excess thyroid hormones stimulate the growth of orbital tissues and increase the amount of fat and muscle behind the eye, pushing it forward. This can result in the noticeable bulging of the eyes. In contrast, other conditions listed, such as hypothyroidism, pituitary adenoma, and thyroiditis, do not typically result in exophthalmos. Hypothyroidism often leads to symptoms like weight gain, fatigue, and sometimes puffiness around the eyes but does not cause the eyes to bulge outwards. Pituitary adenomas can affect hormone levels, including thyroid-stimulating hormone, but they are not directly associated with exophthalmos. Thyroiditis involves inflammation of the thyroid gland, which can alter hormone levels, but again, it does not usually present with protrusion of the eyes.

Thus, hyperthyroidism is definitively linked to exophthalmos because of the underlying mechanisms that lead to