If your thyroid gland works too quickly, then too much thyroid hormone is produced, and too much thyroid hormone enters your bloodstream and your body. Another word for a thyroid that works too quickly is hyperthyroidism. The most common cause of hyperthyroidism is Graves' disease.

Hyperthyroidism onset in children or adolescents

A thyroid gland that works too quickly starts to do so during childhood or adolescence. This is what we call acquired hyperthyroidism. Usually, you get this disease from an auto-immune reaction in which your body produces stimulating antibodies against the TSH receptor. This makes your thyroid gland work more rapidly (Graves' Disease). Other, less frequently occurring causes, are: Hashitoxicosis, a (sub-)acute thyroid infection, toxic multinodular goiter or several thyroid nodules, a thyroid gland damaged by radiation or injury, an overstimulated thyroid gland due to an excess of iodine or a problem with the pituitary gland (pituitary adenoma).

What are the symptoms of hyperthyroidism?

Every child with hyperthyroidism has his or her own individual symptoms, and they are not all equally affected by the symptoms they do have. The more severe a hyperthyroidism is, the more symptoms you will have. In young children, the symptoms are sometimes difficult to recognize, because they are not yet able to talk about their symptoms. Symptoms may include:

• Behavior: trouble sleeping, fatigue, mood instability, irritability, reduced ability to concentrate, restlessness, stressed and agitated behavior (hyperactivity).
• Skin and hair: red cheeks, increased perspiration, clammy skin.
• Head-throat: palpable swelling in the throat (goiter), bulging eyes.
• Stomach-intestinal tract: frequent hunger, diarrhea.
• Muscles and joints: reduced muscle tone, reduced strength.
• Bodily functions: increased heart rate, heart palpitations, high blood pressure, shortness of breath with exertion.
• Hyperactive reflexes, trembling hands.
• Menstrual disorders.
• Sensitivity to heat, feeling hot.
• Weight loss.
• Accelerated longitudinal growth, tall for age.

How is hyperthyroidism diagnosed?

If you have symptoms that seem to point to a thyroid gland that is working too quickly, tests can be performed. A blood sample is taken and an ultrasound of the thyroid gland or a radioactive uptake test with iodine or technetium can be performed (a test that makes the functioning thyroid gland tissue visible).

A blood sample is taken from a blood vessel in your arm (vene puncture) or hand to see how much free T4, T3 and TSH is present. In the case of hyperthyroidism due to a problem in the thyroid gland itself, free T4 is too high and TSH is low. The presence of autoantibodies against the thyroid gland and against TPO, thyroglobulin (Tg) and the TSH receptor are also checked to diagnose or rule out an auto-immune disease (Graves' disease or Hashitoxicosis).

A blood sample is taken from a blood vessel in your arm or hand to see how much free T4, T3 and TSH is present. In the case of hyperthyroidism due to a problem in the thyroid gland itself, free T4 is too high and TSH is low. The presence of autoantibodies against the thyroid gland and against TPO, thyroglobulin (Tg) and the TSH receptor are also checked to diagnose or rule out an auto-immune disease (Graves' disease or Hashitoxicosis).

For a radioactive uptake test, a small amount of labeled iodine (I-123) or technetium will be introduced into your bloodstream via an IV. After that, a series of images (a scintigram) will be made at various moments. These images show to what extent the thyroid gland takes up the labeled iodine or technetium. In Graves' disease, the entire thyroid gland takes up increased quantities of iodine; with a nodule (such as a toxic adenoma), the increased uptake is only local. In that case, the nodule takes up a great deal of iodine, while the rest of the thyroid gland does not.

If the problem is not the thyroid gland but the hypothalamus or the pituitary, then the free T4 will be too high and the TSH will usually be normal or just slightly increased. This seldom occurs during childhood or adolescence.

Graves' Disease

Graves' disease is an auto-immune disease. This means that there is a disruption in your immune system. Your immune system protects you from intruders, such as bacteria and viruses, so that you do not get sick. It is a very intelligent system that can recognize, attack and deactivate foreign substances that enter your body. When this happens, you will often have fever, swelling, pain and redness: the signs of an infection. Sometimes this response is intense, and sometimes you hardly notice it. If you have an auto-immune disease, your immune system attacks your own tissues, just as if they were foreign substances. With Graves' disease, that is your TSH receptor. It is not clear why the immune system does this. Children with certain chromosomal abnormalities (such as Down's or DiGeorge's syndromes,) and children with other auto-immune diseases (such as diabetes) have a greater chance of getting Graves' disease.

If you have Graves' disease, your body makes antibodies against your TSH receptors. The TSH receptors are located in the thyroid gland and bind to TSH (thyroid-stimulating hormone). This binding process initiates thyroid hormone production. TSH fits perfectly into the receptor, like a key in a lock. The antibody against the TSH receptor (TSI, thyroid-stimulating immunoglobulin) also fits perfectly into the receptor and can also stimulate the thyroid to synthesize and secrete more thyroid hormone (T4 and T3). In the case of Graves' disease, antibodies against TPO and Tg can also be made, in addition to the antibody against TSI.

How frequently does Graves' disease occur in children?

Graves' disease is the most frequently occurring cause of hyperthyroidism in children; it affects one in 5000 children. It most often affects children between the ages of 11 and 15 and usually girls, who suffer from the disease five times more often than boys. Younger children can also contract Graves' disease, but this does not occur frequently.

What are the symptoms and features of Graves' disease?

If you have Graves' disease, your thyroid gland works too quickly. This results in symptoms, although these symptoms vary from child to child, and not all children are equally affected by the symptoms they do have. The longer the child has had hyperthyroidism, the more symptoms he or she will have. In young children, the symptoms are sometimes difficult to recognize, because they are not yet able to talk about their symptoms. Symptoms may include:

• Behavior: trouble sleeping, fatigue, mood instability, irritability, reduced ability to concentrate, restlessness, stressed and agitated behavior (hyperactivity).
• Skin and hair: red cheeks, increased perspiration, clammy skin.
• Head-throat: palpable swelling in the throat (goiter), bulging eyes.
• Stomach-intestinal tract: frequent hunger, diarrhea.
• Muscles and joints: reduced muscle tone, reduced strength.
• Bodily functions: increased heart rate, heart palpitations, high blood pressure, shortness of breath with exertion.
• Hyperactive reflexes, trembling hands.
• Menstrual disorders.
• Sensitivity to heat, feeling hot.
• Weight loss.
• Accelerated longitudinal growth, tall for age.

TSH receptors are also present in the muscles around the eye and in the fat and connective tissue of the eye socket, which is affected by TSI. These tissues can become inflamed and enlarged. This causes the eyeball to be pushed forward, and your eyes can protrude as a result (proptosis).

How is Graves' disease diagnosed?

If you have symptoms that seem to point to a thyroid gland that is working too quickly, tests can be performed. A blood sample is taken and an ultrasound of the thyroid gland or a radioactive uptake test with iodine or technetium can be performed (a test that makes the functioning thyroid gland tissue visible).

A blood sample is taken from a blood vessel in your arm or hand (vene puncture) to see how much free T4, T3 and TSH is present. With Graves' disease, free T4 is too high and TSH is low. The TSI autoantibody levels are clearly increased, and the antibodies against TPO are normal or increased.

With an ultrasound of the throat, you can clearly see the structure and size of the thyroid gland. When you have Graves' disease, there are no nodules on the thyroid gland.

For a radioactive uptake test, a small amount of labeled iodine (I-123) or technetium will be introduced into your bloodstream via an IV. After that, a series of images (a scintigram) will be made at various moments. These images show to what extent the thyroid gland takes up the labeled iodine or technetium. In Graves' disease, the thyroid gland tissue takes up more iodine or technetium.

How is Graves' disease treated?
There are several treatments for a thyroid gland that works too quickly:

• Medicines;
• Administration of radioactive iodine;
• Surgery.

Medicine is the treatment most commonly chosen, because improvements in the condition can occur spontaneously. This is also called remission.

Thiamazole. Thyrostatic medicines (e.g. thiamazole) inhibit the function of your thyroid gland. As a result, you no longer produce your own thyroid hormone. Since you need thyroid hormone, you will also have to take levothyroxine daily. During the course of this treatment, the TSI levels in your blood must occasionally be tested. If no more TSI is found after two years, you may stop the treatment. You will have to have regular check-ups, though. There is a chance that you will relapse (recidivism). This occurs in approximately 70-80% of all children.

Thiamazol (Strumazol®) prevents the synthesis of thyroid hormone in the thyroid gland. The tablets (10 or 30 mg) must be taken once or twice per day. The number of pills you must take depends on your body weight. This medicine does not work as soon as you start taking it. You must take it for several days to several weeks before it works optimally. Thiamazole also has a number of side effects: a reduction in the number of white blood cells, reduced liver function, allergic reactions, and muscle and joint pains. If you have too few white blood cells, you are less optimally protected against infections. So, if you take this medicine and have fever, throat pain or other signs of infection, you must immediately contact the hospital or your treating physician. You will be given antibiotics. Regular blood tests, which check the number of white and red blood cells and your liver function, are important.

If you do not have enough thyroid hormone, you must take a daily dose of the hormone in the form of levothyroxine (Thyrax®, Euthyrox® or Eltroxin®). With levothyroxine, you may choose tablets or a drink; the lowest single-tablet dose is 25 micrograms. However, the tablets are easy to split into two or four pieces. The official advice is to take levothyroxine approximately one half hour before eating and not to mix it with food containing locust bean gum or soy. These substances bind with the thyroid hormone in the levothyroxine. Levothyroxine can be taken in the morning or in the evening. Contrary to the official advice, you may also take this medicine shortly before eating. In this case, however, you should take it in the same way every day so that it becomes a habit. If you take other medicines (such as gastric acid blockers or medicines containing iron), this may have an influence on the uptake of the thyroid hormone. Your doctor and pharmacist can tell you more about this. To verify that the prescribed dosage is correct, blood will be taken regularly and tested for TSH and FT4 levels.
Thyroid hormone can also cause side effects; if you take too much, you may develop heart palpitations and feel stressed and agitated. It can also cause sleep problems.

If you are suffering from hyperthyroidism, it may be necessary to use extra medicines. If your heart rate is too fast or if you regularly experience heart palpitations, you may be given a medicine to return your heart action to normal. For example, propanolol can be prescribed. Propanolol is a beta blocker that slows the heart rate and lowers blood pressure.

Treatment with radioactive iodine. A thyroid gland that works too quickly can also be treated with radioactive iodine. This iodine-131 can be injected directly into the bloodstream via an IV, but you can also swallow it in tablet form. This way, the radioactive iodine is taken up by your blood from the stomach-intestinal tract. The radiation emitted by the radioactive iodine will damage the thyroid gland cells that take up this iodine and reduce the function of the thyroid gland. In young children, the thyroid gland must be switched off completely. The hypothyroidism that results from this, must then be treated with thyroid hormone in the form of thyroxine tablets.

Surgery (thyroidectomy). One of the options for treatment of hyperthyroidism is surgery in which the entire thyroid gland is removed. The operation is performed under anesthesia. This procedure must be executed with the utmost precision, because many vulnerable organs are situated next to the thyroid gland, such as nerves and the parathyroid glands. After the operation, you must take thyroxine (thyroid gland hormone), and the functioning of your parathyroid glands will be carefully monitored.

Hashitoxicosis

Hashitoxicosis is a thyroid gland that is temporarily working too quickly. After a few months, this thyroid gland will begin to work too slowly. In such cases, Graves' disease is first suspected, but then the diagnosis (quickly) changes to Hashimoto's thyroiditis. In the first phase of this disorder, the thyroid gland produces too much thyroid hormone because it is being stimulated by antibodies against the TSH receptor (TSI, thyroid-stimulating immunoglobulin, and TBI, thyroid-blocking immunoglobulin). After that, the thyroid gland cells are attacked by the immune system. As a result of this attack, they are severely damaged. At this stage, antibodies against TPO and Tg can often be found in the blood.

How can Hashitoxicosis be treated?
Since the functioning of the thyroid gland changes after a few weeks or months, you will primarily receive medicines to treat the symptoms. For severe heart palpitations due to a thyroid gland that is working too rapidly, for example, you may be prescribed propanolol. Propanolol is a beta blocker that slows the heart rate and lowers blood pressure.

In exceptional cases, if you are suffering from many complaints and symptoms of hyperthyroidism, the function of the thyroid gland is inhibited using thiamazole (Strumazol®). Thiamazole (Strumazol®) prevents the synthesis of thyroid hormone in the thyroid gland. The tablets (10 or 30 mg) must be taken once or twice per day. The number of pills you must take depends on your body weight. This medicine does not work as soon as you start taking it. You must take it for several days to several weeks before it works optimally. Thiamazole also has a number of side effects: a reduction in the number of white blood cells, reduced liver function, allergic reactions, and muscle and joint pains. If you have too few white blood cells, you are less optimally protected against infections. So, if you take this medicine and have fever, throat pain or other signs of infection, you must immediately contact the hospital or your treating physician. You will be given antibiotics. The use of thiamazole may cause your thyroid gland to grow. If you already have goiter, then it must be closely monitored. Regular blood tests, which check the number of white and red blood cells and your liver function, are important.

If you do not have enough thyroid hormone, you must take a daily dose of the hormone in the form of levothyroxine (Thyrax®, Euthyrox® or Eltroxin®). With levothyroxine, you may choose tablets or a drink; the lowest single-tablet dose is 25 micrograms. However, the tablets are easy to split into two or four pieces. The official advice is to take levothyroxine approximately one half hour before eating and not to mix it with food containing locust bean gum or soy. These substances bind with the thyroid hormone in the levothyroxine. Levothyroxine can be taken in the morning or in the evening. Contrary to the official advice, you may also take this medicine shortly before eating. In this case, however, you should take it in the same way every day so that it becomes a habit. If you take other medicines (such as gastric acid blockers or medicines containing iron), this may have an influence on the uptake of the thyroid hormone. Your doctor and pharmacist can tell you more about this. To verify that the prescribed dosage is correct, blood will be taken regularly and tested for TSH and FT4 levels.

Thyroid hormone can also cause side effects; if you take too much, you may develop heart palpitations and feel stressed and agitated. It can also cause sleep problems.

Toxic multinodular goiter

With this disorder, your thyroid gland works too quickly. An enlarged thyroid gland with several nodules can be seen on an ultrasound. Blood work does not show any autoantibodies (TSI). A radioactive uptake test shows that the nodules take up too much iodine and are extremely active; they produce too much thyroid hormone. This condition does not occur very frequently in childhood. It occurs more frequently in children with McCune-Albright Syndrome; approximately one in three of these children have this type of hyperthyroidism.

How is toxic multinodular goiter treated?
You will be treated with antithyroid medicines, such as thiamazole. Surgery or treatment with radioactive iodine may be necessary in some cases.

Thiamazole (Strumazol®) prevents the synthesis of thyroid hormone in the thyroid gland. The tablets (10 or 30 mg) must be taken once or twice per day. The number of pills you must take depends on your body weight. This medicine does not work as soon as you start taking it. You must take it for several days to several weeks before it works optimally. Thiamazole also has a number of side effects: a reduction in the number of white blood cells, reduced liver function, allergic reactions, and muscle and joint pains. If you have too few white blood cells, you are less optimally protected against infections. So, if you take this medicine and have fever, throat pain or other signs of infection, you must immediately contact the hospital or your treating physician. You will be given antibiotics. The use of thiamazole may cause your thyroid gland to grow. If you already have goiter, then it must be closely monitored. Regular blood tests, which check the number of white and red blood cells and your liver function, are important.

Treatment with radioactive iodine. A thyroid gland that works too quickly can also be treated with radioactive iodine. This iodine-131 can be injected directly into the bloodstream via an IV, but you can also swallow it in tablet form. This way, the radioactive iodine is taken up by your blood from the stomach-intestinal tract. The radiation emitted by the radioactive iodine will damage the thyroid gland cells that take up this iodine and reduce the function of the thyroid gland. In young children, the thyroid gland must be switched off completely. The hypothyroidism that results from this must then be treated with thyroid hormone in the form of levothyroxine tablets.

Surgery (thyroidectomy). One of the options for treatment of hyperthyroidism is surgery in which the entire thyroid gland is removed. The operation is performed under anesthesia. This procedure must be executed with the utmost precision, because many vulnerable organs are situated next to the thyroid gland, such as nerves and the parathyroid glands. After the operation, you must take levothyroxine (thyroid gland hormone), and the functioning of your parathyroid glands will be carefully monitored.