The study is a single-center prospective cohort study of clinical application of continuously monitored data by wearable activity trackers in the patients with thyrotoxicosis. The purpose of the study is to evaluate the association between parameters of pulse rate, activity, and sleep from wearable activity trackers and the thyrotoxic status along with the treatment.

Activity trackers to be used: Fitbit Charge HR (TM)

Data which ware provided by Fitbit app (TM) will be analyzed in this study.

Inclusion Criteria:

• Patients undergoing newly developed or recurrent thyrotoxicosis who are treated and followed-up in Seoul National University Bundang Hospital
• Patients who can use wearable activity trackers and smartphone applications
• In case of Graves' disease, patients who will treated by anti-thyroid drugs

Exclusion Criteria:

• Patients who have thyrotoxic periodic paralysis
• In case of Graves' disease, patients who will treated by radioactive iodine therapy or thyroidectomy
• Patients who have thyrotoxicosis due to toxic nodular disease

Adults (20 to 60 years) undergoing newly developed or recurrent thyrotoxicosis who can use wearable activity trackers and smartphone applications