Autoimmune hyperthyroidism in patients with multiple sclerosis treated with interferon beta-1b

Objective: To report symptomatic autoimmune hyperthyroidism developing in patients with multiple sclerosis (MS) treated with interferon beta-lb (IFN-beta-1b). Report of Cases: A 44-year-old woman experienced gradually worsening fatigue, depression, and motor function several months after beginning therapy with IFN-beta-1b for MS. Graves disease associated with episodic palpitations, shortness of breath, hair loss, increased appetite, weight loss, and insomnia was confirmed with endocrinologic studies. Increased fatigue and weakness developed in a 52-year-old woman several months after starting IFN-beta-1b therapy. She also noted sweats, heat intolerance, palpitations, increased appetite, and irritability, and endocrinologic evaluation supported a diagnosis of Graves disease. Conclusions: To our knowledge, this is the first report of autoimmune thyroid disease associated with IFN-beta-1b treatment in patients with MS. Psoriasis has also been reported during interferon therapy for MS, and similar phenomena occur during interferon therapy for hepatitis C. Since some symptoms of thyroid dysfunction may be difficult to distinguish from typical MS-related symptoms, thyroid hormone levels should be checked when unexplained constitutional symptoms occur during IFN-beta-1b therapy.