Goitre. Coloured scintigram of an enlarged thyroid gland (goitre). The thyroid is an endocrine gland found in the neck, responsible for the production of hormones controlling the body's metabolism. This condition is usually due to a deficiency in iodine, which is used to produce the hormones. The release of thyroid stimulating hormone (THS), to speed up hormone production, causes the swelling. A large goitre will cause a person's neck to swell and may cause breathing and swallowing difficulties. Treatment may involve iodine replacement or surgical removal. A scintigram shows the activity of the thyroid gland using a radioactive iodine tracer, which emits gamma rays that are detected by a gamma camera.