Introduction
	Various aspects of radioiodine (131I) treatment have almost exhaustively been dealt with in recent reviews1–4. Despite being in use for more than 50 years, initially for hyperthyroidism and shortly thereafter for thyroid carcinoma, and an overwhelming number of publications, it is surprising that so many fundamental questions remain unanswered (1–5). While much information is available with regard to 131I-treatment of toxic goitre (mainly Graves’ disease), this review will highlight present knowledge of 131I-treatment also in benign non-toxic goitre and focus on aspects needing further research. Recently, the cancer risk after diagnostic and therapeutic use of 131I in thyroid disorders has thoroughly been reviewed in e.g. Thyroid International6. Present knowledge indicates that the marginally increased mortality among hyperthyroid patients the first year after diagnosis is not related to the 131I-therapy but the underlying disease5,6. Consequently, the main focus of this review will be on other aspects of 131I-treatment in benign thyroid disorders. Indications and contraindications for 131I-therapy are listed in Table 1 and 2, respectively. Table 1: Indications for radioiodine treatment in benign thyroid disease Toxic diffuse goitre (Graves’ or Basedow’s disease) Toxic multinodular goitre (Plummer’s disease) Toxic uninodular goitre Non-toxic diffuse goitre Non-toxic multinodular goitre Non-toxic uninodular goitre (autonomous nodule/hot nodule)