Irritability is a symptom of Graves' diease.
Graves' disease is an autoimmune condition, meaning that the body's immune system mistakes healthy cells for foreign invaders and attacks them.
A number of conditions can cause hyperthyroidism, but Graves' disease is the most common, affecting around 1 in 200 people. It most often affects women under the age of 40, but it is also found in men.
Contents of this article:
Here are some key points on Graves' disease. More detail and supporting information is in the main article.
- Graves' disease is the most common cause of hyperthyroidism.
- It is the most common type of autoimmune disease in the United States.
- Graves' disease affects an estimated 2-3 percent of the world's population.
What is Graves' disease?
Graves' disease was originally known as "exophthalmic goiter" but is now named after Sir Robert Graves, an Irish doctor who first described the condition in 1835.
The disease affects the thyroid gland, which is a butterfly-shaped organ at the base of the neck, just below the Adam's apple. It is an important part of the endocrine (hormone) system, and regulates metabolism by releasing hormones into the bloodstream.
Graves' disease is the most common autoimmune disorder in the U.S.
Hormones released by the thyroid gland help keep the body's metabolism running at the right rate. The more hormones it releases, the more quickly metabolism runs. Normally, a chemical called thyroid-stimulating hormone (TSH) produced in a part of the brain called the pituitary, tells the thyroid how much or how little to produce.
In Graves' disease, the immune system produces antibodies that trigger the TSH receptor, tricking the thyroid into making too many hormones, which speeds up metabolism, causing the symptoms below.
Symptoms of Graves' disease
The overproduction of thyroid hormones can have a variety of effects on the body, symptoms can include:
- increased sweating
- weight loss (without change in diet)
- hand tremors
- changes in menstrual cycle
- erectile dysfunction and reduced libido
- anxiety and irritability
- an irregular or rapid heartbeat
- Graves' dermopathy - thick red skin on the shins (rare)
- enlargement of the thyroid gland (goiter)
- heart failure
One feature of Graves' disease that is different from other types of hyperthyroidism, is its effects on the eyes. Graves' disease is the only type of hyperthyroidism that is associated with swelling and inflammation of the eye tissue.
Because of increased pressure on the optic nerves, if untreated, it can potentially lead to double vision and even partial blindness.
It is still unclear why Graves' disease affects the eyes in this way. The severity of the condition does not correlate with the severity of eye symptoms; it can occur before the condition begins, or even without Graves' disease.
What causes Graves' disease?
Smoking is a risk factor for Graves' disease.
Unfortunately, scientists do not know the exact cause of Graves' disease. We know that, somehow, the body's immune system is tricked into targeting receptors on the thyroid gland, causing hyperthyroidism.
Research suggests that Graves' disease may be caused by a combination of genetic and environmental factors.
- Genetic - A family history of Graves' disease increases the chance of developing the condition, although its inheritance pattern is unknown.
- Environmental - you are much more likely to develop Graves' disease if you smoke.
Other people who have an increased risk include:
- Individuals with other autoimmune diseases.
- Women who have recently given birth or are pregnant.
- Individuals under emotional or physical stress.
Tests and diagnosis of Graves' disease
Graves' disease can be difficult to diagnosis at first. Aside from ophthalmopathy, most of the symptoms of Graves' disease are shared with other conditions.
Thyroid-stimulating hormone (TSH) stimulates the thyroid gland to release thyroxine (T4) and triiodothyronine (T3); a doctor may take a blood sample to measure levels of these hormones.
Abnormally high levels of T3 and T4, and a very low level of TSH, are good indications of Graves' disease.
Another test for Graves' disease is called radioactive iodine uptake. The patient consumes a small quantity of radioactive iodine by liquid or capsule. Once swallowed, the iodine collects in the thyroid.
The doctor will then perform several scans using a radioactive tracer, the first is usually done 4-6 hours after the iodine has been taken. Following this, a second scan is usually taken 24 hours later.
Treatments for Graves' disease
There are a variety of treatments available for Graves' disease. The majority are aimed at inhibiting the overproduction of thyroid hormones by targeting the thyroid gland; others aim to reduce the symptoms.
Radioactive iodine therapy
The most commonly utilized treatment for Graves' disease is radioactive iodine therapy; it has been used since the 1940s. It is still popular because it is non-invasive and highly effective.
Radioactive iodine is taken orally and directly targets the thyroid gland. Iodine is used by the thyroid gland to make thyroid hormones. When medication is taken, the radioactive iodine soon builds up in the thyroid gland and slowly destroys any overactive thyroid cells.
This results in a reduction in size of the thyroid gland, and fewer thyroid hormones being produced. Although there have been concerns that the radiation might increase risk of thyroid cancer, so far, no study has measured an increased danger. However, there is a very small risk of secondary cancers that may result from this treatment.
Two common drugs that target the thyroid are propylthiouracil and methimazole; the latter is most common in the United States.
Anti-thyroid medication helps prevent the thyroid gland from producing excess amounts of hormones by blocking the oxidation of iodine in the thyroid gland.
Symptoms normally improve within 4-6 weeks of starting medication. Anti-thyroid drugs can often be used in conjunction with other treatments such as radioactive iodine therapy or surgery.
Medication may continue for 12-18 months to make sure that the condition does not come back.
Beta blockers are traditionally prescribed to deal with heart problems and hypertension. They work by blocking the effects of adrenaline and other similar compounds. They can help reduce symptoms in Grave's disease.
Graves' disease patients may be more sensitive to adrenaline, this can result in symptoms such as sweating, shaking, increased heart rate, and anxiety. Beta blockers can help alleviate these symptoms, but do not address Graves' disease itself.
Beta blockers are often used alongside other treatments, meaning there is a risk that side-effects can occur due to the different drugs interacting with one another.
Because other treatments for Graves' have steadily improved, surgery is now less common. However, it is still used if other treatments are unsuccessful.
Thyroidectomy is the removal of all or part of the thyroid gland - how much depends on the severity of the symptoms.
The biggest advantage of surgery is that it is arguably the fastest, most consistent, and most permanent way to restore normal thyroid hormone levels.
After surgery, patients may experience neck pain and a hoarse or weak voice, however, these should just be temporary, due to the breathing tube that is inserted into the windpipe during surgery.
A scar will be present after surgery, the severity of it will depend on how much of the thyroid is removed. If only part of the thyroid is removed, the remaining portion is able to take over its functions. However, if the entire thyroid is removed, the body will be unable to produce enough thyroid hormones, a condition known as hypothyroidism. To treat this, a doctor will prescribe hormone pills, which replace the effect of the hormone.