Hyperthyroidism is the result when the thyroid is overactive and produces excess thyroid hormones. This causes the body’s functions to speed up, thus causing many different parts of the body to work faster.
The thyroid is a butterfly-shaped gland in the neck, in front of the windpipe. In adults, it is about 2cm wide and 4cm high.
The thyroid gland makes two hormones: thyroxine (also called T4) and triiodothyronine (also called T3). Together, these hormones regulate the body’s growth and metabolism, that is, how quickly the body burns energy and how quickly reactions happen inside the body. The production of thyroid hormones in the thyroid is controlled by another hormone called thyroid stimulating hormone (TSH). This is made by the pituitary gland in the brain.
Hormones are carried in the bloodstream and the purpose of the hormones of the thyroid is to keep the body’s functions (metabolism) working at the correct pace.
About one in 500 men and one in 50 women will develop hyperthyroidism at some point in their lives.
Symptoms
Hyperthyroidism can mimic other health problems, making it difficult to diagnose. It has many different symptoms, mostly due to the speeding up of the body’s metabolism. Symptoms include the following:
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- Losing weight despite having an increased appetite (although around one in 10 people will gain weight)
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- Feeling nervous, anxious, irritable or emotional
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- Feeling tired
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- Shortness of breath, especially when exercising
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- Muscle weakness
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- Tremor (shaking) of the hands and fingers
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- Having difficulty sleeping
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- Being intolerant of heat and perspiring more than usual
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- Irregular or increased heart rate or palpitations
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- Having infrequent menstrual periods or problems getting pregnant
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- Having more frequent bowel movements or diarrhoea
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- Loss of hair or finer hair than usual
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- Enlarged thyroid gland (goitre)
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- Swollen, red or tearing eyes, protruding eyeballs, discomfort on one or both eyes or double vision (in the case of Graves’ ophthalmopathy).
Causes
Under normal conditions, the thyroid produces the correct amount of hormones to regulate the body’s functions at the correct pace, but sometimes it produces too much thyroxine. This may be caused by a number of reasons, including the following:
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- Grave’s disease is an autoimmune disorder in which antibodies produced by the immune system stimulate the thyroid to produce excessive thyroxine. It is not sure what causes Graves’ disease, but genetics may play a role.
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- Hyperfunctioning thyroid nodules is a form of hyperthyroidism in which one or more adenomas (nodules or parts of the thyroid) produce too much thyroxine. Once again the reason for the adenomas producing too much hormone is not known.
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- Thyroiditis is an inflammation of the thyroid gland which can cause excess thyroid hormone stored in the gland to leak into the bloodstream. Some types of inflammation cause pain, whereas others are painless and may occur after pregnancy.
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- Too much iodine may cause hyperthyroidism as the thyroid gland uses iodine to produce thyroid hormones. Taking too much medicines containing iodine, such as amiodarone for irregular heart beats, may therefore cause hyperthyroidism.
Treatment
A blood test will confirm that someone has hyperthyroidism and can also be used to determine if it is caused by some of the conditions mentioned above. An iodine uptake test and an ultrasound scan may also be done. The results, the sufferer’s age, physical condition and the severity of the disorder will determine the specific treatment.
Various types of treatment are:
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- Anti-thyroid medications gradually reduce the signs and symptoms of hyperthyroidism by preventing your thyroid gland from producing excessive amounts of hormones. Medication, usually for 12 to 18 months, should be taken under doctor’s supervision. Beta-blockers may be used to relieve the symptoms of hyperthyroidism.
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- In the case of Graves’ ophthalmopathy, treatment with corticosteroids may be prescribed to reduce swelling. In some cases an operation may be an option.
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- The non-surgical treatment used for hyperthyroidism is radioiodine treatment in the form of a tablet or a drink. As the radioactivity builds up, it destroys some of the thyroid tissue, causing a decreased production of thyroid hormone. However, it is difficult to determine beforehand what the outcome will be. Alternatively, a single large dose of radioiodine may be given to stop all thyroid activity. Thyroxine replacement medicines will then be prescribed to prevent hypothyroidism. Radioiodine is not suitable for pregnant women or while breastfeeding.
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- When the sufferer does not respond to other treatments, can’t take anti-thyroid medicines, if thyroid cancer is diagnosed or if she is pregnant, an operation may be done to remove all or part of the thyroid gland (thyroidectomy). After the operation, thyroxine replacement medicines will be prescribed and should be taken for the rest of the person’s life.
Complications
If left untreated, hyperthyroidism can lead to serious complications such as the following:
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- Heart problems, such as rapid heart rate, a heart rhythm disorder called atrial fibrillation and congestive heart failure
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- Osteoporosis because too much thyroid hormone interferes with the body’s ability to incorporate calcium into bones. The strength of bones depends, in part, on the amount of calcium and other minerals they contain
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- Graves’ ophthalmopathy causes eye problems, including bulging, red or swollen eyes, sensitivity to light and blurring or double vision
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- Graves’ disease may also affect the skin, causing redness and swelling, often on the shins and feet.
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- Hyperthyroidism places the sufferer at risk of thyrotoxic crisis, that is, sudden intensification of symptoms, leading to a fever, a rapid pulse and even delirium. If this occurs, seek immediate medical care.
Our Employee Wellbeing Programme (EAP) is available 24 hours a day if you want to know more about thyroid problems.