Enlarged thyroid organs similar to those of endemic mixture struma may occur in people that don’t have iodine deficiency. These goitrous glands could secrete traditional quantities of thyroid hormones, however a lot of oftentimes, the secretion of hormone is depressed, as in endemic mixture struma. The exact reason for the enlarged thyroid in patients with upset mixture struma isn’t celebrated, but most of those patients show signs of gentle thyroiditis; therefore, it’s been steered that the inflammation causes slight glandular disorder, that then ends up in increased thyrotrophic hormone secretion and progressive growth of the noninflamed parts of the organ. this might make a case for why these glands sometimes area unit nodular, with some parts of the organ growing whereas alternative parts area unit being destroyed by inflammation. In some persons with mixture struma, the thyroid has associate degree abnormality of the accelerator system needed for formation of the thyroid hormones. Among the abnormalities typically encountered area unit the following:
1. Deficient iodide-trapping mechanism, in which iodine isn’t pumped up adequately into the thyroid cells.
2. Deficient oxidase system, during which the iodides are not change to the iodine state.
3. Deficient coupling of chemical element tyrosines within the thyroglobulin molecule, so the ultimate thyroid hormones can’t be fashioned.
4. Deficiency of the deiodinase accelerator, which prevents recovery of iodine from the chemical element tyrosines that aren’t coupled to make the thyroid hormones (this is concerning 2 thirds of the iodine), thus resulting in iodine deficiency.
Finally, some foods contain goitrogenic substances that have a propylthiouracil-type of antithyroid activity, thus conjointly resulting in TSH-stimulated enlargement of the thyroid gland. Such goitrogenic substances area unit found especially in some kinds of turnips and cabbages.