What are the treatment options for an overactive thyroid?

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An overactive thyroid can be treated with medication, surgery or radioactive iodine. The most suitable treatment option will mainly depend on the cause of the disease.

If the thyroid gland makes too many hormones and releases them into the bloodstream, it can lead to things like weight loss, nervous restlessness and a rapid heartbeat. An overactive thyroid (hyperthyroidism) can have various underlying causes. The most common of these is called Graves’ disease. It also often develops if cells in the thyroid gland start making too many hormones "autonomously" – in other words, without being instructed to by the pituitary gland, which is normally the case. These autonomous cells are either found in nodules or spread throughout the whole gland.

Mild hyperthyroidism may get better on its own, without treatment. In most cases, though, the symptoms get worse without treatment. Taking medication is sometimes enough to keep the symptoms under control. But they usually only go away completely in the long term if treated with surgery or radioactive iodine (radioiodine therapy).

When are the different treatments used?

If the thyroid gland is producing too many hormones, the first step of treatment is usually to slow down the production of hormones using medication. The hormone levels need to return to normal before other treatments can be started. If the overactive thyroid is being caused by "autonomous" thyroid cells, the next step of treatment is often radioiodine therapy. If the thyroid gland has become very large, surgery to remove it is usually recommended. In Graves' disease, taking medication for several months is often enough to make the thyroid function return to normal. In about half of all people, the thyroid gland becomes overactive again when they stop taking the medication. Surgery or radioiodine therapy are then considered.

The choice of treatment doesn't only depend on what is causing the overactive thyroid: For instance, the medication isn't always well tolerated, and some people would rather not have surgery. It is then a good idea to discuss the available treatment options with the doctor.

What medications can be used?

The main medications used for the treatment of an overactive thyroid are known as anti-thyroid drugs. These reduce the production of thyroid hormones. Thiamazole (also called methimazole) and carbimazole are the most commonly used anti-thyroid drugs. If these drugs aren't tolerated, propylthiouracil is sometimes used. It's always a good idea to discuss the benefits and drawbacks of these drugs with your doctor. The most common side effects of anti-thyroids include skin rashes, fever and joint problems. If a fever arises, it's important to see a doctor immediately because the fever could be a sign of a blood disorder (agranulocytosis) – although this is rare.

Sometimes a medication called perchlorate is used instead. Perchlorate prevents iodine from being absorbed by the thyroid gland. Iodine is a trace element that the thyroid gland needs in order to produce hormones. An overactive thyroid that has access to a lot of iodine can also produce more hormones. Perchlorate is used in, for example, people who have an overactive thyroid and need to have an x-ray examination using iodine-containing contrast agents.

If the overactive thyroid causes a rapid or irregular heartbeat, a beta blocker (usually propranolol) can be taken too. People who have bulging eyes due to Graves' disease can also use steroids.

Surgery

The aim of surgery will depend on the situation. If one single nodule (adenoma) is responsible for the thyroid being overactive, the surgeon will remove the nodule or the affected half of the gland only, and that is enough. If the whole gland is enlarged, and "autonomous" thyroid tissue or nodules are spread throughout it, the entire gland is usually removed. This is also done if someone is having surgery for an overactive thyroid caused by Graves' disease.

As well as the general risks associated with surgery – such as bleeding, wound infections or wound healing problems – there is a risk that the recurrent laryngeal nerve (Nervus recurrens) may become damaged during surgery. This can cause hoarseness and, in very rare cases, breathing problems. Damage to the parathyroid glands is possible too. These approximately lentil-sized glands are located on the back of the thyroid gland. They regulate the calcium balance in the body. If surgery causes hoarseness or problems affecting the function of the parathyroid glands, they are usually only temporary.

Radioiodine therapy

When the thyroid gland produces thyroid hormones, it absorbs iodine from the blood. Radioiodine therapy makes use of this: Radioactive iodine (radioiodine) is swallowed in the form of a capsule or dissolved in water. It is then absorbed by the thyroid gland, where it destroys overactive cells. This reduces the production of thyroid hormones. The amount of radiation is very low, and most of it leaves the body on its own within a few days. To avoid exposing other people and the environment to radiation, people who have radioiodine therapy in Germany stay in hospital for a few days. During this time, they stay in a special isolation room and generally aren't allowed to have visitors. The effects of radioiodine therapy only become noticeable after a few weeks.

Radioiodine therapy is not suitable for pregnant women and breastfeeding mothers. In people who have Graves' disease, radioiodine therapy might increase the risk of eye-related symptoms such as bulging eyes or vision problems.

Severe complications from radioiodine therapy are very rare. For instance, the level of thyroid hormones in the blood might increase temporarily because the destroyed cells release stored thyroid hormones. This can cause similar symptoms to those caused by an overactive thyroid, such as heart problems. Because of this, people who are at higher risk of cardiovascular disease are advised to take anti-thyroid medication too if they have radioiodine therapy. Radioiodine therapy is currently not believed to increase the risk of cancer. But research in this area hasn't reached any clear conclusions.

People who have thyroid surgery or radioiodine therapy often have an underactive thyroid gland (hypothyroidism) afterwards. This is particularly likely if a lot of the thyroid gland was removed or many gland cells were destroyed. In people who have Graves' disease, the aim of surgery or radioiodine therapy is actually to completely remove or destroy all of the thyroid gland tissue. The thyroid gland is then no longer able to produce thyroid hormones, so you usually have to take thyroid hormone tablets for the rest of your life. Taken at the right dose, the tablets are well tolerated. If the dose is too high, they may cause problems similar to the symptoms of an overactive thyroid, such as a rapid heartbeat.