An overactive thyroid or hyperthyroidism can be caused by the following conditions –
Thyroiditis – in particular Graves’ disease
Toxic ( or overactive ) nodule
Toxic multinodular goitre
Graves disease
Graves’ disease is a condition characterised by the presence of antibodies that act against the TSH receptor on thyroid cells ( TRABS). These antibodies stimulate the TSH receptor causing thyroid growth, increased blood supply, increased hormone production and secretion. It may have affects on other organs such as the eyes ( Graves’ ophthalmopathy) or skin.
Graves disease is more common in women. It can be associated with other autoimmune diseases such as diabetes, pernicious anaemia, rheumatoid arthritis and lupus.
Graves’ disease is usually treated medically at first with medication that reduces hormone production. Medication commonly used includes carbimazole and propylthiouracil. Side effects are rare but serious and will be discussed by the prescribing doctor.
If medical treatment fails or is required beyond a year, more definitive treatment may be recommended. This can be either radioactive iodine or surgery. The decision as to which is most appropriate is based on many factors and also patient preference.
If surgery is required this will be a total thyroidectomy.
Toxic Nodule or toxic Multinodular goitre
These are less common causes of hyperthyroidism, whereby one or more nodules are producing too much thyroid hormone. These can be diagnosed as the cause on a radioiodine nuclear medicine scan. Treatment will initially be with medication to reduce hormone production however definitive treatment is needed for long term control and cure.
Definitive treatment will be either radioactive iodine or surgery. Surgery is preferred for sizeable nodules particularly if they are causing compressive symptoms, if there is any concern about cancer or is there is a need for rapid return to normal thyroid hormone levels. In the case of a single overactive nodule, a hemithryoidectomy is the surgery of choice. In other cases of toxic nodule or toxic multinodular goitre, radioactive iodine may be appropriate.