 We will screen all patients residing in the extended region around Stockholm, Sweden who have been referred and admitted to the Radiumhemmet clinic for investigation and usually treatment with radioiodine. As of February 2016, we will also include patients referred for treatment with antithyroid drugs at the endocrinology clinics of 1 Sahlgrenska University Hospital, Gothemburg Sweden, 2 Karolinska University Hospital, Stockholm, Sweden, 3 Danderyds Hospital, Stockholm, Sweden 