Immunosuppressive therapy is a form of treatment that is based on the use of medications that suppress the activity of the immune system. In the setting of thyroid eye disease, immunosuppressive therapy is targeted to suppress the activity of white blood cells that infiltrate the tissues surrounding the eyeballs. The medication most commonly used in the treatment of thyroid eye disease is a glucocorticoid called prednisone. Glucocorticoids are steroid hormones that are similar to a hormone produced by the adrenal glands called cortisol. They help to reduce inflammation by blocking the movement of white blood cells that infiltrate tissues. In the setting of thyroid eye disease, glucocorticoids may also block the production of glycosaminoglycans that contribute to swelling in the eye sockets. Prednisone is usually very effective in providing rapid relief of many of the bothersome symptoms associated with mild to moderate thyroid eye disease. Patients who are treated with effective doses may notice marked relief of irritation, redness, watering, and foreign body sensations within 48 hours. In cases of severe thyroid eye disease, continued treatment with prednisone may be lead to gradual improvement in the function of compressed optic nerves and trapped extraocular muscles.
When prednisone is used to treat active thyroid eye disease, it is usually started at a dose of 60-80 milligrams per day. This dose is gradually tapered over the course of several weeks before it is discontinued altogether. This strategy helps to avoid many of the side effects associated with long-term treatment with high doses of glucocorticoids. Significant side effects may include weight gain, thinning of the bones, diabetes mellitus, psychological disturbances, and oversuppression of the immune system that may increase the risk of contracting certain types of infections. Glucocorticoids may also be administered as high-dose intravenous infusions of a medication called methylprednisolone. This approach is less commonly used in practice.
An alternative approach to immunosuppressive therapy may focus on the use of a medication called cyclosporine A. This medication is more commonly used to prevent rejection in patients who have undergone organ transplants. When it is used in the setting of thyroid eye disease, cyclosporine A may block the production of cytokines that promote inflammation of the tissues surrounding the eyeballs. Patients who are treated with cyclosporine A must undergo frequent blood tests to monitor drug levels, as long-term exposure to toxic levels of cyclosporine A may disrupt the normal functioning of the kidneys.
The decision to begin treatment with a course of immunosuppressive therapy is usually based on an overall assessment of the severity of a patient’s thyroid eye disease. Treatment may also be considered when a patient with active thyroid eye disease is about to receive a dose of radioactive iodine. There is some concern that treatment with radioactive iodine may contribute to progression of thyroid eye disease that may increase the risk of developing complications. Clinical trials have demonstrated that treatment with a course of prednisone that is started before a dose of 131-Iodine is administered may help to prevent this progression.