Can thyroid enlargement occur for different reasons?

Yes, thyroid enlargement—clinically known as a goitre—can occur for several distinct reasons. The thyroid gland may enlarge as a whole or develop one or more nodules.1

Common causes include:

• Iodine Deficiency: This is the most frequent cause of endemic goitre. When iodine intake is low, the pituitary gland secretes excess thyrotropin to stimulate the thyroid, which leads to growth.1
• Autoimmune Disorders: In Graves disease, antibodies mimic thyrotropin, stimulating the gland to grow and function excessively. Conversely, in Hashimoto disease, the gland is infiltrated by lymphocytes, causing inflammation and gradual enlargement.123
• Nodular Growth: The development of one or multiple nodules (uninodular or multinodular goitre) can cause the gland to enlarge.1
• Hormonal Synthesis Defects: Genetic or functional defects in the steps required to synthesize thyroid hormone can trigger compensatory growth.1

While some forms of enlargement are associated with hyperthyroidism or hypothyroidism, the function of the gland in the presence of a goitre may be decreased, normal, or increased.1