Role of autoimmune and familial factors in goiter prevalence. Studies performed in a moderately endemic area.

The goitrogenic role of autoimmune phenomena in endemic goiter is still uncertain. Scanty and discrepant results have been reported in different areas of the world. This prompted us to evaluate the prevalence of circulating thyroid antibodies in an area of North-Western Tuscany during a survey for endemic goiter. The survey was carried out according to the P.A.H.O. criteria in a stable community. In all schoolchildren (n = 142, age range 7-15 yr) and in most of their parents (n = 159), thyroid size was evaluated and urine was collected for iodine determination. Blood was drawn for determination of circulating thyroid microsomal (MAb) and thyroglobulin antibodies (TgAb), TT3, TT4 and TSH. Prevalence of goiter in schoolchildren was 77.9% and 94.8% in their parents. Mean (+/- SD) urinary iodine excretion was 55.0 +/- 2.1 micrograms/24 h. The overall frequency of TgAb and MAb in the adult population was 14.4%, statistically higher than that of control subjects matched for sex and age. The frequency in schoolchildren was 4.3%. The presence of goiter in children was unrelated to the presence of thyroid antibodies in parents, whether goitrous or nongoitrous. A higher prevalence of goiter was found in children with goitrous parents as compared to children with nongoitrous parents (p less than 0.005). In conclusion, the frequency of thyroid autoantibodies in the adult population of the endemic area studied was increased, but showed no relation with the presence of goiter. The prevalence of goiter in children was associated with the presence of goiter but not of thyroid autoantibodies in parents. These data suggest that autoimmune phenomena are of limited importance in the development of endemic goiter.