Insulin-like growth factor 1 (IGF-1) in multinodular goiters: a possible pathogenetic factor.

In order to support previous in vitro studies which had stressed a possible autocrine role for Insulin-like Growth Factor 1 (IGF-1) in thyroid growth regulation, we have investigated the presence of IGF-1, as detected by means of radioimmuno assay and of immunocytochemistry, in thyrocytes from normal thyroid and from multinodular goiter. Our study revealed that IGF-1 is detectable in thyroid cells from multinodular goiter and, to a lesser extent, from normal thyroid. Both techniques used in this study demonstrated that thyrocytes are the site of accumulation of IGF-1 and that stromal cells contain lower amounts of this growth factor. The findings of the present study seem to suggest that thyrocytes could produce IGF-1 in vivo. This feature gives further support to the hypothesis that IGF-1 may regulate thyroid growth and therefore it might be involved in the pathogenesis of multinodular goiter.