A 30-year-old MLT student complains of being tired but is not able to sleep. The woman also states that her hair has been breaking off, and she has lost 20 pounds over the past 2 months without trying. The woman's pulse and blood pressure are elevated, and her eyes seem to be bulging. Her complete blood count (CBC) is normal, thyroid-stimulating hormone is decreased, and T4 is increased. Antimicrosomal and antithyroglobulin antibodies are each 1:400. This woman most likely has:__________.