Diffuse hyperplasia corresponds to the first stages of the natu- ral history. The goitre appears in childhood in endemic areas but, in sporadic cases, it usually occurs at puberty when meta- bolic demands are high. If TSH stimulation ceases the goitre may regress, but tends to recur later at times of stress such as pregnancy. The goitre is soft, diffuse and may become large enough to cause discomfort. A colloid goitre is a late stage of diffuse hyperplasia, when TSH stimulation has fallen off and when many follicles are inactive and full of colloid