Hi Abdul Majeed, Welcome to HealthcareMagic Forum. There are various causes for Thyroid Gland Selling, like Goiter which is common in groups of people who live in areas with iodine poor soil, that is who have Iodine deficiency. A thyroid nodule appears in such cases. The other cause could be Hashimoto s Thyroiditis, which is swelling of the thyroid gland that often results in reduced thyroid function (hypothyroidism). There are various causes for this and it is also associated with autoimmune disorders hence it is also called as Autoimmune thyroiditis where your body will be generating a immune response against your own thyroid gland. All these factors cause Thyroid Gland swelling. The patient has to get him/herself examined by a Endocrinologist as he/she will require medications, to control the symptoms. Sometimes it is surgically removed, either partially or completely. Good Luck.