Iodine treatment of iodine deficiency goitre and autoimmune thyroiditis.: A prospective study

Problem: There is epidermiological and clinical evidence that iodine may in duce or promote the manifestation of autoimmune thyroiditis. For this reason it is important know if substitution of alimentary iodine deficiency or iodine treatment of endemic goitre can cause formation of thyroid antibodies. On the other hand the practical importance of this phenomenon should be evaluated. Patients and Methods: During a prospective study we examined 209 patients with endemic non-toxic goitre and 53 healthy people. For treatment were used 200 mu g iodine/d (n = 119), 500 mu g iodine/d (n = 27), 1.5 mg iodine/week (n = 41), 150 mu g iodine/d plus 75 to 100 mu g T4/d (n = 26), 100 mu g iodine plus 180 Ctg T4/d (n = 24). The observation took 1 pear with a 3-month intervall for,check ups including clinical examination, ultrasound, TSH, T3, fT4, TPO-and thyreoglobuline antibodies and urinary iodine. Results: After 12 months 7.5% of iodine treated persons had produced antibodies, most of them at low levels. In healthy people we found increased antibody-levels in 3.8%, in patients with goitre in 9.0%, in patients with nodular goitres in 11.6%. 500 mu g iodine caused the most antibody reaction in 14.8%. People treated with 200 mu g iodine/d showed positive antibody levels in 5%. T4 seems to reduce antibody-reactions. Pathological antibody-levels were not found in patients with combined iodine/T4- and single-T4 therapy. Among the 22 primary pathological antibody levels only 4 increased further (18.2%). Three of them belonged to the group of 5 persons treated with 500 mu g iodine/d. Primary high antibody values were normalized ill 5 patients (22.7%). Hypothyroid disturbances were not found. Ultrasound did not show any alterations, and the reduction of thyroid volumes in antibody-positive patients was not affected. Median urinary iodine excretion during the observation-intervall was 5.2 to 7.2 mu g/dl. Conclusions: Possible antibody reactions have no clinical importance at all. Individual cases must be observed. Low iodine doses should be prefered. Combined iodine/T4 treatment seems to have an advantage regarding immunological thyroidal reactions.