Who it affects
Hyperthyroidism is also known as thyrotoxicosis or an over active thyroid and is a relatively common disorder. An over active thyroid may result from various causes. Patients with Graves disease are usually younger, female and may have a history or family history of diseases such as rheumatoid arthritis, pernicious anaemia or Addison`s disease. Patients with Graves disease may develop Graves ophthalmopathy (picture above). Multiple benign overactive thyroid nodules is another cause. This is called a toxic multi-nodular goitre. More rarely an overactive thyroid can be due to drugs such as Amiodarone or a single hyperactive thyroid nodule (toxic nodule). Postpartum thyroiditis refers to abnormal thyroid function following the delivery of a child.
What gland is involved
The thyroid gland lies in the front part of the neck just under skin and below the thyroid cartilage (Adam`s apple).
Hyperthyroidism may cause symptoms such as weight loss, increased appetite, tremor of the hands, palpitations, loose motions or menstrual irregularity.
The blood tests used to diagnose an overactive thyroid are Thyroid Stimulating Hormone (TSH), free T4 and sometimes free T3. Free T4 is produced by the thyroid in response to TSH stimulation. Free T4 is converted to free T3, the more active form of the hormone. TSH is produced by the pituitary and because of thyroid hormone feedback, levels are low or undetectable in hyperthyroidism. The tests used to determine what caused thyroid over activity may include blood tests (thyroid anti-bodies), ultrasound scans or thyroid isotopes scans.
The treatment of an overactive thyroid is dependent on the cause. Graves` disease is typically treated with anti-thyroid medication (Carbimazole or Propylthiouracil) for 6-18 months. Once discontinued, about 50% of patients may remain off medication. In those whom an over active thyroid re-occurs (relapse), treatment with radioiodine or surgery may be considered.
Anti-thyroid medication may be titrated to control thyroid function or used in a “block and replace” fashion. Block and replace therapy entails using anti-thyroid medication to block thyroid hormone production and levothyroxine replacement to normalise TFTs.
Hyperthyroidism due to a multinodular goitre is usually treated with radioiodine or surgery, although medication is usually prescribed initially.
About half of patients with Graves` disease are able to successfully discontinue all medication after a closely monitored course of anti-thyroid medication.
Patients treated with surgery (total thyroidectomy) or radioiodine (ablative doses) usually become hypothyroid and require lifelong thyroxine therapy.
Thyroid surgery is arranged by referring to a surgeon.
Surgical removal of the entire thyroid gland will result in hypothyroidism and require lifelong levothyroxine therapy. The parathyroid glands lie behind the thyroid and although efforts are made to avoid it, these may also be removed during total thyroidectomy surgery. Such patients may require lifelong vitamin D therapy.
Some surgeons aim to achieve normal thyroid function off medication by removing part of the thyroid gland. With this approach, there is however a chance that the thyroid remains overactive or becomes overactive at a later time.
Radioiodine is a popular alternative to surgery. It involves the administration of the isotope I131 that is administered in the form of a liquid or tablet. Patient will be advised to take certain precautions e.g. avoiding contact with young children and pregnant women for a period of time after treatment. The main side-effect of radioiodine therapy (ablative dose) is to render the patient`s thyroid under active. Life-long levothyroxine therapy is required in this case. It is important that if you are considering radioiodine therapy, you mention to your endocrinology specialist if:
1. you come into contact with children or pregnant women
2. you suffer from urinary incontinence
3. plan to conceive
4. you are a carer for someone