Hyperthyroidism

Hyperthyroidism Overactive Thyroid What is hyperthyroidism?

Hyperthyroidism is a condition when the thyroid gland produces too much thyroid hormone. When this occurs, the body’s metabolism is increased, which can cause a variety of symptoms.

What is the thyroid?

The thyroid is a butterflyshaped gland in the front of the neck, located below the larynx (voice box) and above the clavicles (collarbones).

It produces hormones that regulate how the body uses and stores energy.

Hyperthyroidism can cause the thyroid gland to enlarge. This causes a swelling in the neck called a “goitre”. Hyperthyroidism caused by Graves’ disease can also make the eyes bulge.

Causes of hyperthyroidism 1. Graves’ disease Graves’ disease is the most common cause. It is not clear why it develops in most people, although it more common in certain families.

In Graves’ disease, the immune system produces an antibody that stimulates the thyroid gland to produce too much thyroid hormone. This is most common in women between the ages of 20 and 40, but can occur at any age in men or women. Some people develop eye problems causing dry, irritated or red eyes, and double vision. In severe cases, swelling behind the eyes can cause them to bulge out.

2. Nodular goitre with toxicity One or more thyroid nodules (small growths or lumps in the thyroid gland) can produce too much thyroid hormone.

3. Thyroiditis Painless (‘silent or lymphocytic’) thyroiditis and postpartum thyroiditis are disorders in which the thyroid becomes temporarily inflamed and releases excess thyroid hormone into the bloodstream, causing hyperthyroidism.

4. Drug-induced (Iatrogenic) hyperthyroidism Taking too much thyroid hormone supplement for hypothyroidism Symptoms of hyperthyroidism Patients can have one or more of the following symptoms: • Anxiety, irritability, trouble sleeping • Weakness (in particular the upper arms and thighs, making it difficult to lift heavy items or climb stairs) • Tremors (of the hands) • Perspiring more than normal, difficulty tolerating hot weather • Rapid or irregular heartbeats • Fatigue • Weight loss in spite of a normal or increased appetite • Frequent bowel movements In addition, some women have irregular menstrual periods or stop having their periods altogether. This can be associated with infertility. Men may develop enlarged or tender breasts, or erectile dysfunction, which resolves when hyperthyroidism is treated.

Diagnosis of hyperthyroidism Hyperthyroidism can be diagnosed with simple blood tests that measure the amount of thyroid hormone and thyroid-stimulating hormone (TSH). Typically, the thyroid hormone level is high and the TSH level is low.

Beta-blockers do not reduce thyroid hormone production but they can control many of the bothersome symptoms, such as rapid heart rate, tremors, anxiety, and heat intolerance. Once the hyperthyroidism is under control, the beta-blocker is stopped.

Treatment for hyperthyroidism Hyperthyroidism can be treated using medicines, radiation, or surgery. Many factors, such as your age and the severity and type of hyperthyroidism, are important in determining which treatment is best.

b) Radioactive iodine Destroying the thyroid with radiation is called radioiodine ablation and this is a permanent way to treat hyperthyroidism.

Medications The two main types of medicines used to treat hyperthyroidism are: a) Anti-thyroid drugs Examples are carbimazole and propylthiouracil (PTU) which work by decreasing how much thyroid hormone the body makes.

People with very mild Graves’ disease have a 50 to 70 percent chance of remission.

It is possible to have a relapse years later, and most people will need to eventually consider permanent treatment with radioactive iodine or surgery.

Most people who take radioiodine develop hypothyroidism and will need to take thyroid hormone supplements for the rest of their lives.

People who are treated with radioiodine should avoid close physical contact, especially with young children and pregnant women, for three to seven days after treatment because of the possibility of exposing them to low doses of radiation. This can be difficult for parents of young children.

Surgery Surgical removal of the thyroid is a permanent cure for hyperthyroidism. It is recommended when: • A large goitre blocks the airways, making it difficult to breathe. You cannot tolerate anti-thyroid drugs and you do not want to use radioiodine.

There are risks to the mother and the developing baby if hyperthyroidism is not well controlled; these risks can be avoided or minimised with frequent monitoring and medication adjustment throughout the pregnancy.

• For patients with severe thyroid eye disease which is threatening their vision.

Women who are pregnant or breastfeeding should not be treated with radioactive iodine.

A woman should wait at least six months after radioactive iodine treatment before trying to become pregnant.

• Long term replacement with thyroid hormone is required after surgery if the entire thyroid gland has been removed.

Contact us If you have any further queries or clarifications, you can make an appointment through our hotline 6555 8828.

• There is a nodule in the thyroid gland that could be cancer.

Pregnancy & hyperthyroidism Women who take anti-thyroid drugs and want to become pregnant should discuss this with their doctor. For pregnant women, propylthiouracil (PTU) is the preferred drug during the first trimester.

Yishun Health is a network of medical institutions and health facilities in the north of Singapore, under the National Healthcare Group.

Admiralty Medical Centre • (65) 6807 8000 • www.admiraltymedicalcentre.com.sg Khoo Teck Puat Hospital • (65) 6555 8000 • www.ktph.com.sg Yishun Community Hospital • (65) 6807 8800 • www.yishuncommunityhospital.com.sg The information is correct at the time of printing and subject to revision without further notice.

GS.PE.06.0419