While it is well established that autoimmune factors are the cause of
goiter and
hyperthyroidism in
Graves' disease, these factors are not yet considered relevant in the development of thyroid autonomy. While an increased overall frequency of anti-Tg and anti-TPO
antibodies has been found in moderate
iodine-deficient areas, where thyroid autonomy is more frequently observed, there was evidence indicating that thyroid autoimmune phenomena were the consequence rather than the cause of the
goiter.
Thyroid Stimulating Antibodies (TSAb) have been reported in sera of patients with nodular autonomous
goiter, but their pathogenetic relevance is uncertain, since these findings could not be confirmed by others. In our experience TSAb were detected in few cases with multinodular nontoxic
goiter and were always associated with anti-TG and anti TPO
antibodies, indicating that these patients have the nodular variant of
Graves' disease. Besides TSAb, Thyroid Growth Stimulating
Antibodies (TGAb) have been detected by different techniques in several goitrous conditions, including
Graves' disease and sporadic or endemic nontoxic
goiter. The precise nature of TGAb remains to be clarified, and particularly the relationship between TGAb and TSAb is still a matter of controversy. However, data indicating that TGAb cannot be dissociated from TSAb in Graves' sera suggest that these
antibodies can be regarded as a sufficient pathogenetic agent for the development of both
goiter and thyroid hyperfunction in
Graves' disease. The relevance of TGAb in euthyroid goitrous conditions is uncertain, since conflicting results have been reported.(ABSTRACT TRUNCATED AT 250 WORDS)