Hello, Good day, Noted that you are on Neomercazole and Warfarin. Why are you on Warfarin? Do you have Atrial fibrillation? If so, did that occur after you had Grave s Hyperthyroidism? If that is the case, AF might revert to normal once hyperthyroidism is controlled. One can develop Hypothyroidism with Neomercazole which can cause ankle swelling. But that usually, will not be tender. . In rare chances, Warfarin can cause bleeding in joints and thus swelling. But that is very rare and occurs only if INR is too high. One more possibility of tender swellings in legs in Grave s disease is due to Pretibial Myxedema .The best way is to examine your ankles and do an INR. I am sure that your endocrinologist would have thought of all these rare possibilities. Do you have any breathing difficulty or shortness of breath on lying down??. Has an ECG been performed? Regards Binu