Graves\' disease (GD) is a systemic autoimmune disorder characterized by the infiltration of thyroid antigen-specific T cells into thyroid-stimulating hormone receptor (TSH-R)-expressing tissues. Stimulatory autoantibodies (Ab) in GD activate the TSH-R leading to thyroid hyperplasia and unregulated thyroid hormone production and secretion. Diagnosis of GD is straightforward in a patient with biochemically confirmed thyrotoxicosis, positive TSH-R-Ab, a hypervascular and hypoechoic thyroid gland (ultrasound), and associated orbitopathy. In GD, measurement of TSH-R-Ab is recommended for an accurate diagnosis/differential diagnosis, prior to stopping antithyroid drug (ATD) treatment and during pregnancy. Graves\' hyperthyroidism is treated by decreasing thyroid hormone synthesis with the use of ATD, or by reducing the amount of thyroid tissue with radioactive iodine (RAI) treatment or total thyroidectomy. Patients with newly diagnosed Graves\' hyperthyroidism are usually medically treated for 12-18 months with methimazole (MMI) as the preferred drug. In children with GD, a 24- to 36-month course of MMI is recommended. Patients with persistently high TSH-R-Ab at 12-18 months can continue MMI treatment, repeating the TSH-R-Ab measurement after an additional 12 months, or opt for therapy with RAI or thyroidectomy. Women treated with MMI should be switched to propylthiouracil when planning pregnancy and during the first trimester of pregnancy. If a patient relapses after completing a course of ATD, definitive treatment is recommended; however, continued long-term low-dose MMI can be considered. Thyroidectomy should be performed by an experienced high-volume thyroid surgeon. RAI is contraindicated in Graves\' patients with active/severe orbitopathy, and steroid prophylaxis is warranted in Graves\' patients with mild/active orbitopathy receiving RAI.

The version 5 of the guideline for radioiodine therapy of benign thyroid disorders is an update of the version 4, which was published by the German Society of Nuclear Medicine (Deutsche Gesellschaft für Nuklearmedizin, DGN) in co-ordination with the German Society of Endocrinology (Deutsche Gesellschaft für Endokrinologie, DGE, Sektion Schilddrüse) and the German Society of General- and Visceral-Surgery (Deutsche Gesellschaft für Allgemein- und Viszeralchirurgie, DGAV) in 2007. This guideline was harmonized with the recommendations of the European Association of Nuclear Medicine (EANM). According to the German \"Directive on Radiation Protection in Medicine\" the physician specialised in nuclear medicine (\"Fachkunde in der Therapie mit offenen radioaktiven Stoffen\") is responsible for the justfication to treat with radioiodine. Therefore, relevant medical indications for radioiodine therapy and alternative therapeutic options are discussed within the guideline. This procedure guideline is developed in the consensus of a representative expert group. This fulfils the level S1 (first step) within the German classification of Clinical Practice Guidelines.

The procedure guideline for radioiodine therapy of differentiated thyroid cancer (version 4) was developed in the consensus of a representative expert group. This fulfils the level S1 (first step) within the AWMF classification of Clinical Practice Guidelines (AWMF, Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften, Germany). This procedure guideline completed the guideline for surgical management of thyroid cancer (level S2) with the aspects from nuclear medicine. Controversies over ablative radioiodine therapy in small papillary thyroid cancers and in minimally invasive follicular cancer without angioinvasion, over empirical standard doses for ablative radioiodine therapy, and over the kind of TSH-stimulation were described and the guideline formulated a corridor of good clinical practice. The text has included the recent results from the National Cancer database and the SEER database (both from the USA), indicating that the ablative radioiodine therapy has improved the survival rate even in low risk patients. Such a statistically significant benefit can be detected only by a national cancer registry with long-term follow-up data.