Natural course of iodine-induced thyrotoxicosis (Jodbasedow) in endemic goiter area: a 5 year follow-up.
In the Balsas region of North Brazil (85% prevalence of goiter), 1876 goitrous subjects (1663 with goiter grade I and II and 103 with grade III multinodular goiter) were treated with 1 ml of iodized oil im (l-oil). From the population with grade III goiter we were able to follow-up for 5 yr 13 euthyroid goitrous patients (group 1) and 8 goitrous individuals (group 2) who developed iodine-induced thyrotoxicosis (IIT, 0.42% of the total population or 7.76% of the multinodular goiter subjects). The two groups were matched for age and goiter size, and had no significant differences in the baseline levels of thyroid hormone concentration, T3/T4 ratio or mean serum TSH. However, group 2 had a higher concentration of serum Tg, and 48 h after challenge with 10 U of bovine TSH (bTSH) had a significantly higher absolute release of T3 and Tg than group 1. In 4 patients IIT was transitory and resolved by 12 months. Four other subjects, however, maintained a mild clinical form of IIT that only normalized at 50 months. Only one patient needed treatment with methylmercaptoimidazol. There was no evidence of autoantibodies (TSH-receptor inhibiting antibody, anti-Tg or anti-microsomal antibodies) against thyroid antigens in group 2 patients. All subjects, including those with thyrotoxicosis, showed a remarkable shrinkage of the goiter by 60 months which was reflected by a significantly lower absolute response of T3 and Tg after bTSH.(ABSTRACT TRUNCATED AT 250 WORDS)
Martins
M C
MC
Division of Endocrinology, Hospital das Clinicas, University of Sao Paulo Medical School, Brazil.
Lima
N
N
Knobel
M
M
Medeiros-Neto
G
G
D001938:Brazil; D005500:Follow-Up Studies; D006042:Goiter / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology; D006801:Humans; D007455:Iodine / Q000009:adverse effects* / Q000627:therapeutic use; D013963:Thyroid Hormones / Q000097:blood; D013971:Thyrotoxicosis / Q000139:chemically induced*; D013972:Thyrotropin / Q000097:blood
D013963:Thyroid Hormones; D013972:Thyrotropin; D007455:Iodine