Inclusion Criteria:  Hyperthyroidism accepted for thyroidectomy due to toxic nodular goiter with free T4 <30 pmol/L or Graves' disease Signed informed consent  Exclusion Criteria:  Unstable coronary artery disease Previous thyroid surgery Congestive heart failure Renal insufficiency Hepatic failure Current infection Treatment with steroids or anticoagulants Thyroid associated orbitopathy CAS > 2 Diabetes mellitus type 1 Active cancer Severe psychiatric illness Amiodarone treatment Pregnancy Breast feeding Women of child bearing potential not using contraceptive Inability to comprehend the meaning of the study Iodine hypersensitivity