Follicular cells convert thyroglobulin, a protein found in follicles into 2 iodine containing hormones: triiodothyronine or T3 , and thyroxine or T4 .

滤泡细滤泡当中的甲状球蛋白成为两种素：甲状原氨酸，又称T3；以及甲状素，又称T4。