The problem of the nodular goiter.

Nodular goiter is a worldwide problem involving millions of persons. Endemic goiter, and associated cretinism, is totally preventable by ensuring an adequate dietary iodine intake and eliminating malnutrition and dietary goitrogens. Therapy, on the other hand, is difficult in that the goiters often do not regress and the cretinoid changes are irreversible. Nonendemic goiter due to autoimmune thyroid disease, genetic defects in thyroid hormone biosynthesis, and environmental goitrogens or neoplasia is not usually preventable. The usual therapy, involving TSH suppression by administration of L-thyroxine orally, will frequently bring about regression of early, diffuse goiters but is often ineffective in bringing about regression of large, multinodular goiters. In these patients, surgical removal of the goiter may be necessary for alleviation of obstructive symptoms. Further research is needed to elucidate the factors involved in the development of these multinodular goiters and to control the autocrine and paracrine factors involved in nodule growth.