Toxic Multinodular Goitres are usually found in more elderly patients, compared to those with Graves' disease. It is thought that there are many interacting causes resulting in periods of thyroid growth and involution. Over time this results in the formation of an autonomous nodule which becomes hyperfunctioning (i.e. it produces too much thyroid hormone). There does seem to be some autoimmune component as thyroid autoantibodies have been found in 25% of patients.