Iodine treatment of iodine deficiency goitre and autoimmune thyroiditis. Aprospective study

Problem: There is epidermiological and clinical evidence that iodine may in duce or promote the manifestation of autoimmune thyroiditis. For this reas on it is important know if substitution of alimentary iodine deficiency or iodine treatment of endemic goitre can cause formation of thyroid antibodie s. On the other hand the practical importance of this phenomenon should be evaluated. Patients and Methods: During a prospective study we examined 209 patients w ith 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/wee k (n = 41), 150 mu g iodine/d plus 75 to 100 mu g T4/d (n = 26), 100 mu g i odine plus 180 Ctg T4/d (n = 24). The observation took 1 pear with a 3-mont h 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 antibo dies, most of them at low levels. In healthy people we found increased anti body-levels in 3.8%, in patients with goitre in 9.0%, in patients with nodu lar 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 level s in 5%. T4 seems to reduce antibody-reactions. Pathological antibody-level s were not found in patients with combined iodine/T4- and single-T4 therapy . Among the 22 primary pathological antibody levels only 4 increased furthe r (18.2%). Three of them belonged to the group of 5 persons treated with 50 0 mu g iodine/d. Primary high antibody values were normalized ill 5 patient s (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 obse rvation-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. C ombined iodine/T4 treatment seems to have an advantage regarding immunologi cal thyroidal reactions.