Hello there, I can understand your concern for your daughter s health. The medicine Neomercazole is used in hyperthyroidism to reduce the increase thyroid hormone in the body. You daughter is responding and in 3 weeks time first the T3 and T4 levels will come down. Gradually TSH will also come to normal range. Her TPO antibodies being above 1000 indicate that this is an autoimmune thyroid disease. Usually when TSH comes below 0.01 we advise patients to go for a Technitium scan which confirms whether this is a transient phase of hyperthyroidism followed by hypothyroidism or chronic hyperthyroidism called as Graves disease. If you have done it then you know the diagnosis if not then do discuss with you endocrinologist who can suggest the same and treat accordingly. The doses of Neomercazole need to be carefully titrated. Do check TSH and T3 T4 again after 4 weeks. Also remember if your daughter ever has fever or sore throat then immediately stop the Neomercazole and get a CBC blood test and report to your doctor. Sometimes, depending on your daughter s age and no near plan of pregnancy one can be given radioactive iodine ablation therapy to stop the thyroid from functioning completely and then replacing externally with thyroid hormones. This is a safer option if given to the right candidate. Do discuss these things with your doctor who will surely guide you for the same. Hope this helps. Take care.