Goitre. Light micrograph of a section through a thyroid gland affected by goitre, showing the enlarged follicles (lower frame) associated with the disease. Goitre is a swelling of the thyroid gland, often due to a deficiency of the essential mineral iodine. The thyroid uses iodine to make hormones that regulate the metabolism. The cells lining the follicles are responsible for hormone production. In goitre, they become bloated with colloid, a fluid also necessary for the production of the hormones. If goitre is due to iodine deficiency alone, increasing dietary iodine can reverse the swelling. If it is due to cancer or an autoimmune disorder, the gland may be removed.