Hyperthyroidism accelerates metabolism and heart rate - with far-reaching consequences such as weight loss, hair loss, high blood pressure, nervousness, sleep disorders or diarrhea.
Thyroid hyperfunction is a dysfunction of the thyroid gland: as a result of over-functioning, the thyroid gland forms too many hormones. These thyroid hormones - thyroxine (T4) and triiodothyronine (T3) - intervene in all metabolic processes of the body. That's why over-caring for the body with hormones boosts metabolism in general.
Strictly speaking, hyperthyroidism is not an independent thyroid disorder. Rather, hyperthyroidism is a symptom of various other disorders.
The symptoms associated with hyperthyroidism are extremely diverse. Because the oversupply of thyroid hormones, the metabolism is generally accelerated. Typical general symptoms of hyperthyroidism include:
- Weight loss with increased appetite and despite adequate nutrition
- Hair loss
- Increased sweating
- Heat intolerance (i.e., those affected quickly experience heat as unpleasant)
Hyperthyroidism also has a noticeable effect on individual organ systems. For example, the cardiovascular system works faster because the thyroid hormones make the body more sensitive to the stress hormones epinephrine and norepinephrine. This effect of hyperthyroidism can trigger the following symptoms:
- Accelerated pulse
- Palpitations to tachycardia
- High blood pressure (hypertension)
Due to its effect on the central nervous system (CNS = brain and spinal cord), thyroid hyperfunction causes symptoms such as:
- Nervousness, restlessness
- Trembling of the hands
- Sleep disorders with increased fatigue
- Mood swings
- Muscle pain and muscle weakness
Diarrhea may also be part of the symptoms of hyperthyroidism. A woman can also develop cycle disorders. In addition, hyperthyroidism usually enlarges the thyroid gland: physicians refer to it as goiter.
Depending on the cause of hyperthyroidism, additional symptoms may be added. For example, in the case of Graves' disease, the eye socket often becomes ill. This endocrine orbitopathy causes the eyeball to emerge. Physicians refer to this symptom as exophthalmos, colloquially called it also Glupschauge, Glotzauge or Glanzauge. How strong it is, says nothing about the degree of hyperthyroidism.
In about every other case, thyroid hyperfunction caused by Graves' disease has two symptoms of exophthalmos: an enlarged thyroid gland and palpitations. If these three classic symptoms for Graves' disease occur at the same time, doctors speak of Merseburger Trias.
Thyroid hyperfunction (hyperthyroidism) can cause many different diseases. The most common causes are Graves' disease and thyroid autonomy.
Hyperthyroidism is often a symptom of the autoimmune disease called Graves' disease (basedow's disease). In autoimmune diseases, the immune system is falsely targeted against the body's own tissue - the cause is unknown. However, hereditary predisposition seems to play an important role.
In Graves' disease, antibodies mistakenly activate hormone production in the thyroid tissue: an antibody directed against the body's own antibodies (autoantibodies) mimics the action of the thyroid stimulating hormone (thyroid stimulating hormone, TSH). The autoantibodies are called TRAK (TSH receptor autoantibodies). As a result, the thyroid gland produces an uncontrolled large amount of thyroid hormones - it comes to hyperthyroidism. Since autoimmune processes are behind it, Graves' disease also means:
- Immunogenic hyperthyroidism or
Thyroid hyperfunction often occurs as a result of thyroid autonomy. "Autonomy" in this context means that the thyroid works independently of external influences according to its own laws: The hormone formation decouples itself from the control by the higher centers in the brain - hypothalamus and pituitary gland (hypophysis).
The cause of thyroid autonomy - and the associated hyperthyroidism - is typically an iodine deficiency. Autonomy can affect the entire thyroid gland or just certain areas. Such an area is called an autonomous adenoma. Depending on the amount of autonomous thyroid tissue thyroid autonomy
- leave the normal thyroid function unimpaired,
- cause only mild hyperfunction of the thyroid gland or too
- associated with pronounced hyperthyroidism.
Only rarely are Graves' disease or thyroid autonomy responsible for hyperthyroidism, but a different disease or other influences. Rare causes of hyperthyroidism include:
- Hormone-forming tumor of the pituitary gland (pituitary gland)
The rare causes of hyperthyroidism include the use of iodine-containing substances (such as X-ray contrast agents or the drug amiodarone for cardiac arrhythmias). In addition, someone who takes too many thyroid hormones can develop a hyperthyroidism factitia. This form of thyroid hyperfunction is self-made in the sense.
About one percent of the population has hyperthyroidism. Women are affected much more often than men. In most cases, hyperthyroidism starts between the ages of 20 and 50 years.
In order to diagnose hyperthyroidism, the doctor determines the thyroid levels in the blood. In an overactive thyroid
- the values for the free thyroid hormones T3 and T4 are almost always increased,
- while the value for thyroid stimulating hormone (thyroid stimulating hormone, TSH) is typically decreased.
If the blood test results in an average TSH value, hypothyroidism is considered excluded.
An oversupply of thyroid hormones alone, however, says nothing about why it came to the thyroid hyperfunction. Therefore, a thorough survey (e.g., about medications taken and previous examinations) and, if necessary, further examinations are needed to narrow down the cause of hyperthyroidism.
Whether a Graves disease is behind the hyperthyroidism, the doctor can determine the so-called Merseburger Triassic (= protruding eyeball, enlarged thyroid gland, tachycardia). In case of doubt, the detection of certain autoantibodies (so-called TRAK, TSH receptor autoantibodies) or a tissue examination using a fine needle biopsy can confirm the diagnosis. In ultrasound examination (sonography), the structure of the thyroid gland in Graves' disease usually looks changed (it is hypoechoic).
If a thyroid autonomy has caused hyperthyroidism, a scintigraphy is helpful: Here you get injected a radiolabeled substance into the vein. After about 20 minutes, the substance can be detected in the thyroid tissue by a special camera. Since healthy and diseased thyroid tissue absorb the substance to varying degrees, the physician can differentiate areas with increased hormone formation (so-called hot knots) from those with normal, low or missing formation (so-called cold knots).
A special diet that helps against hyperthyroidism does not exist. Proper nutrition plays a major role in hyperthyroidism:
- On the one hand, it is advisable that you do not additionally stimulate your metabolism, which is already accelerated by the excess supply of thyroid hormones, with caffeine-containing drinks or alcohol.
- On the other hand, you do not have to make your diet completely iodine-free despite hyperthyroidism. Because iodine is indispensable for the formation of the vital thyroid hormones, which control the metabolism of almost all organ systems (including brain and spinal cord).
Adults have an average daily requirement of about 150 to 200 micrograms of iodine (in pregnancy and lactation, the need for iodine is higher). Normally, it has no negative effects on existing hypothyroidism to absorb these amounts of iodine through the daily diet (with iodine salt, etc.).
Sea fish such as haddock, saithe, plaice and cod are rich in iodine: 100 grams of these fish can contain up to 140 micrograms of iodine. Other important sources of iodine are milk and milk products as well as foods made with iodized table salt (e.g., bread).
If you are on-demand and balanced, you do not have to worry about taking too much iodine. But beware: There should never be more than 500 micrograms of iodine a day in case of hyperthyroidism! When eating a larger iodine intake is therefore essential to avoid. Incidentally, the same applies to external contact with iodine. Therefore, in hyperthyroidism:
- No consumption of sea algae (e.g., sushi) in large quantities because the iodine content of algae varies widely and can be extremely high
- No consumption of iodine-containing healing water
- No use of iodine-containing skin or wound disinfectants
- No iodine-containing medications (like amiodarone)
- No studies with strongly iodine-containing X-ray contrast media
When hyperthyroidism (hyperthyroidism), the treatment primarily aims to improve the symptoms. This can be done by
- an operation or
- radioiodine therapy (i.e., by delivery of radioactive iodine).
Whether medications are suitable for treatment of hyperthyroidism and what the doctor prescribes depends mainly on the cause of hyperthyroidism.
If Graves' disease is behind your hyperthyroidism, you will receive mainly tablets from the drug group of thyroid drugs (thiamazole and carbimazole). These drugs inhibit the formation of thyroid hormones and so relieve the symptoms of hyperthyroidism.
Often it is advisable in the case of Graves' disease to take the antithyroid drugs for about one year, as relapses are common within the first few months. If a relapse occurs after several years, an operation or a radioactive iodine therapy is possible to remedy the hyperthyroidism.
However, if you have hyperthyroidism as a result of thyroid autonomy, antithyroid drugs are not suitable for the treatment: although antithyroid drugs inhibit thyroid hormone production even in this case. After discontinuation of the medication, however, the autonomy remains unchanged. For the therapy to have a lasting effect, you should continue to take the medication. The problem is the possible side effects - such as:
- Allergic reactions with rash,
- joint pain,
- muscle aches and
- in very rare cases also a disturbed blood formation and disturbed liver function.
Lifetime use of the medication is therefore not advisable. Therefore, with thyroid hyperfunction, thyroid autonomy often precludes the choice of surgery or radioiodine therapy.
If your organism's sensitivity to the stress hormones epinephrine and norepinephrine is increased as a result of hyperthyroidism, there are other medicines available for treatment: in this case, beta-blockers such as the propranolol active ingredient help.
Under certain circumstances, an operative treatment is possible in case of hyperthyroidism. The operation is useful in an overactive thyroid, for example, if
- Graves' disease causes your hyperthyroidism and you have a relapse (recidivism) despite treatment with drugs or
- Thyroid autonomy is the cause of your hyperthyroidism.
To surgically repair thyroid hyperfunction, the surgeon must remove as much of the functional thyroid tissue as possible so that the remainder is insufficient to flood the body with thyroid hormones. This means:
- If hyperthyroidism is due to thyroid autonomy, which affects only a specific area of the thyroid gland (autonomic adenoma), the surgeon removes only this area.
- An overall enlarged thyroid removed the surgeon almost completely (subtotal).
If there is not enough thyroid tissue left after the operation to supply the body with sufficient hormones, hypothyroidism is replaced by hyperthyroidism. However, these can be treated without any problems with hormone replacement therapy (with the active ingredient L-thyroxine).
Most thyroid surgery has no lasting consequences. Only in two to three out of a hundred cases permanent and serious complications occur. Examples:
- When the surgeon injures the vocal cord nerve (recurrent laryngeal nerve), which is just behind the thyroid gland, it often causes hoarseness and a weak voice.
- If the surgeon inadvertently removes the parathyroid glands with the thyroid tissue, there may be a lack of calcium in the blood with muscle spasms (tetany), which can be treated by medication.
The surgical treatment of hyperthyroidism also carries - as any surgery - the risk that it may subsequently lead to rebleeding. In any case, carefully consider whether hyperthyroidism requires surgical treatment. In addition, it is recommended to look for an experienced surgeon.
Under certain circumstances, surgical treatment may be useful in case of hyperthyroidism, but too risky. Some people also strongly refuse to undergo surgery for hyperthyroidism. In such cases, radioiodine therapy can help.
The radioiodine therapy used for hyperthyroidism is a radiation treatment of the thyroid gland. To do this, take a radioactive iodine isotope - iodine 131 -, which specifically targets the thyroid tissue and thus reduces thyroid hyperfunction. For other organs, treatment means only a negligible dose of radiation. Also, a connection between this form of therapy and cancer is not yet known.
In pregnancy and lactation, however, it is not recommended to proceed with a radioactive iodine therapy for hyperthyroidism. After treatment, it is also recommended to postpone a possible desire to have children for at least six months.
In the case of hyperthyroidism, the course and prognosis depend primarily on what causes the dysfunction of the thyroid gland:
- Graves' disease, which is often associated with hyperthyroidism, is self-limiting in up to 50 percent of the cases - in other words, the disease returns on its own. However, the disease can recur even after several years.
- Thyroid autonomy, also often responsible for hyperthyroidism, has a less favorable prognosis: it never returns on its own. In addition, the amount of autonomous tissue in the thyroid gland that causes hyperfunction may increase over years. Then the hyperthyroidism may worsen until the thyrotoxic crisis. To prevent this, surgery or radioiodine therapy is advisable if the thyroid is autonomous.
Hyperthyroidism may be associated with various complications in its course.
A possible complication of any hyperthyroidism - regardless of its cause - is the thyrotoxic crisis. This hyperthyroidism makes life-threatening worse. Symptoms include:
- high fever
- accelerated pulse (tachycardia)
- muscle weakness
If the hyperthyroidism remains untreated in such a condition, it leads to disturbances of consciousness and confusion in the further course of the crisis and finally to coma and circulatory failure. The thyrotoxic crisis is a life-threatening emergency situation that requires rapid intensive medical care.
A thyrotoxic crisis in hyperthyroidism may have various causes. Often it arises in an unrecognized hyperthyroidism of the thyroid by the supply of too much iodine (for example, in X-ray contrast media). Insufficiently treated hyperthyroidism as well as additional stress (for example secondary diseases, severe infections, accidents or narcosis) can trigger a thyrotoxic crisis.
Other possible complications of hyperthyroidism include sudden hypoperfusion (ischemia) of the brain and related strokes. Even young adults with hyperthyroidism are nearly 50 percent more likely to have a stroke than people whose thyroid gland is functioning normally.
Thyroid hyperfunction (hyperthyroidism) can only be prevented to a limited extent. Because it is often caused by diseases whose formation you can not influence.
But an overactive thyroid can also have other - external - causes that can be avoided. For example, hyperthyroidism can be caused by overdosage of thyroid hormones or application of iodine-containing substances (such as medications or X-ray contrast agents). To prevent such hyperthyroidism means: take the respective substances only in the prescribed dose or administer only carefully!
Therefore, it is advisable to always examine the thyroid function before the regulation of iodine-containing substances or before surgery.