It should be noted that having a goiter doesn’t necessarily mean that the thyroid gland isn’t working normally. Even when it’s enlarged, the thyroid may produce normal amounts of hormones. It might also, however, produce too much or too little Thyroxine and T-3. A number of factors can cause the thyroid gland to enlarge:
Iodine deficiency: In the developing world, people who live inland or at high elevations are often iodine-deficient and can develop goiter when the thyroid enlarges in an effort to obtain more iodine. Although a lack of dietary iodine is the main cause of goiter in many parts of the world, this is not the case in countries where iodine is routinely added to table salt and other foods.
Graves’ disease: Goiter can sometimes occur when the thyroid gland produces too much thyroid hormone (hyperthyroidism). In Graves’ disease, antibodies produced by the immune system mistakenly attack the thyroid gland, causing it to produce excess thyroxine. This overstimulation causes the thyroid to swell.
Hashimoto’s disease: Goiter can also result from an underactive thyroid (hypothyroidism). Like Graves’ disease, Hashimoto’s disease is an autoimmune disorder. But instead of causing the thyroid to produce too much hormone, Hashimoto’s damages the thyroid so that it produces too little. Sensing a low hormone level, the pituitary gland produces more TSH to stimulate the thyroid, which then causes the gland to enlarge.
Multinodular goiter: In this condition, several solid or fluid-filled lumps called nodules develop in both sides of the thyroid, resulting in overall enlargement of the gland.
Solitary thyroid nodules: In this case, a single nodule develops in one part of the thyroid gland. Most nodules are noncancerous (benign) and don’t lead to cancer.
Thyroid cancer: Thyroid cancer is far less common than benign thyroid nodules. Cancer of the thyroid often appears as an enlargement on one side of the thyroid.
Pregnancy: A hormone produced during pregnancy, human chorionic gonadotropin (HCG), may cause the thyroid gland to enlarge slightly.
Inflammation: Thyroiditis is an inflammatory condition that can cause pain and swelling in the thyroid.