The thyroid gland is located in the area of the larynx. It surrounds the trachea laterally and from the front. The right and left lateral lobes of the thyroid gland are connected by a small bridge. This structure gives the thyroid gland its typical butterfly shape.
The size of the thyroid gland varies from person to person without necessarily being pathological. In the case of a pathological enlargement of the thyroid gland(goitre), there may be
- a visible thickening of the thyroid gland and
- breathing or swallowing difficulties if there is an inward thickening,
may occur.
The position and appearance of the thyroid gland © SciePro | AdobeStock
The thyroid gland produces and stores the hormones triiodothyronine (T3) and tetraiodothyronine (T4). These influence
- the energy metabolism,
- the oxygen consumption of the cells
- the function of the cardiovascular system and
- the gastrointestinal tract.
They are also important for the growth and mental development of unborn babies and children.
An important component of both thyroid hormones is iodine. It must be present in the body in sufficient quantities for the thyroid hormones to be produced. Iodine enters the blood via the gastrointestinal tract and then into the thyroid gland, where it is incorporated into the thyroid hormones.
The thyroid gland can adapt iodine intake to the supply and store available iodine. Excess iodine is excreted via the kidneys.
When and in what quantity the thyroid hormones are produced and released is regulated by higher-level bodies in the brain. Responsible for this are
- the hypothalamus (part of the diencephalon) and
- the pituitary gland (hypophysis).
If the hormone level in the blood falls below the normal value, the pituitary gland releases a hormone called TSH (thyroid stimulating hormone). It stimulates the production of thyroid hormones. These are then released into the blood so that the hormone level in the blood rises again.
The release of TSH is controlled by the hormone TRH (thyrotropin releasing hormone), which is released by the hypothalamus. If the hormone level in the blood rises sharply above the normal value, this control mechanism is set in motion in the opposite direction.
The most common thyroid diseases include hyperthyroidism (overactive thyroid), hypothyroidism (underactive thyroid) and thyroid cancer.
Overactive thyroid (hyperthyroidism)
In hyperthyroidism, there is an oversupply of thyroid hormones in the body. The most common causes of hyperthyroidism are Graves' disease and thyroid autonomy.
Like Hashimoto's thyroiditis (see hypothyroidism),Graves' disease is an autoimmune disease. As a result of an excessive reaction of the immune system, the body produces antibodies against the body's own tissue. These activate the receptors for TSH located on the thyroid cells. This leads to uncontrolled production and release of large quantities of thyroid hormones.
In thyroid autonomy, parts of the thyroid gland produce thyroid hormones uninhibitedly. At the same time, they do not obey the higher-level centers.
The autonomous thyroid tissue can be diffusely distributed or present in one or more nodules. This is referred to as an autonomous adenoma or a hot nodule.
Hyperthyroidism leads to weight loss despite an unchanged or even increased appetite. It can lead to
- hair loss,
- increased sweating,
- diarrhea,
- in women also menstrual cycle disorders
may occur. As thyroid hormones have a stimulating effect on the cardiovascular system, the heart rate increases.
The influence of hyperthyroidism on the central nervous system manifests itself in
- Nervousness,
- restlessness,
- trembling and
- sleep disorders.
Underactive thyroid (hypothyroidism)
In hypothyroidism, the body receives too few thyroid hormones. The most common cause of hypothyroidism is autoimmune thyroiditis (e.g. Hashimoto's thyroiditis). This destroys thyroid tissue.
The thyroid gland is therefore unable to meet the demand for thyroid hormones. The effect of thyroid hormones in the body can also be insufficient.
A distinction is made between primary, secondary and tertiary hypothyroidism.
Primary hypothyroidism can already be congenital. In this case, the body either has no thyroid gland or one that is too small, or the thyroid gland cannot utilize ingested iodine. More frequently, however, primary hypothyroidism develops in the course of life,
- after inflammation of the thyroid gland,
- after thyroid surgery or radiation,
- after radioiodine therapy or
- due to the intake of certain medications.
Diseases of the higher-level centers, i.e. the pituitary gland or the hypothalamus, lead to secondary or tertiary hypothyroidism. In this case, the thyroid gland itself is intact, while the production and release of the hormones TSH and TRH are impaired (usually as a result of a tumor).
In Hashimoto's thyroiditis, antibodies are formed against the body's own thyroid tissue. This leads to inflammation of the thyroid gland, as a result of which an insufficient amount of thyroid hormones can no longer be produced.
Those affected often suffer from
- tiredness,
- lack of drive,
- an increased need for sleep,
- memory disorders,
- frequent chills,
- constipation and
- weight gain.
Their skin is dry, cool and pale, hair and nails are brittle. The pulse is slow and muscle reflexes are weakened. Women may experience menstrual irregularities.
Warning signs in newborns in the case of congenital hypothyroidism are
- Unwillingness to drink,
- constipation and
- a slow pulse.
Newborns and children with hypothyroidism often have no desire to move and usually have flabby muscles.
Thyroid cancer (malignant tumors of the thyroid gland)
Thyroid cancer, also known as thyroid carcinoma, can occur in any part of the thyroid gland. In around 75% of cases, thyroid carcinomas originate from the cells of the thyroid gland in which thyroid hormones are produced. Tumors of this origin are also known as differentiated carcinomas.
Thyroid cancer is a rather rare tumor disease in Germany , with around 7,000 people being diagnosed each year. It can occur at any age, but is most common between the fourth and fifth decade of life. Women are affected more frequently than men.
If thyroid cancer is detected early, the chances of recovery are good.
The doctor examines the patient's general condition and takes a medical history (anamnesis).
Palpation of the thyroid gland provides an initial impression of the size and extent of the thyroid gland. An ultrasound examination(sonography) can provide more precise information about the shape, size and extent of the thyroid gland.
The TSH value (see hormone regulation cycle) is first determined by means of a blood test. If this is outside the normal range, the amount of thyroid hormones in the blood can be determined. The determination of antibodies can also provide further information (e.g. in the case of Hashimoto's thyroiditis or Graves' disease).
Thyroid diagnostics using ultrasound © Alexander Raths | AdobeStock
Another diagnostic option is scintigraphy. Among other things, it can be used to examine the functional state of the thyroid gland in more detail. A distinction can be made between areas with different levels of activity. The radiation exposure of a scintigraphy is usually lower than that of an X-ray examination. In addition, tissue particles from the thyroid gland can be removed and examined by means of a puncture.
In addition, a general laboratory examination and an electrocardiogram (ECG) are performed before thyroid surgery under general anesthesia.
In individual cases, it may be useful to check the function of the vocal cords. An ear, nose and throat specialist would also be consulted for this.
In addition to the comprehensive examination, the patient's suitability for anesthesia and surgery must be clarified.
Thyroid hormones should be within the normal range at the time of thyroid surgery. This means that any malfunction (especially hyperthyroidism) should be treated temporarily with medication.
An enlarged thyroid gland should be operated on if it is obstructing other organs. For example, a constricted trachea or oesophagus can cause swallowing or breathing difficulties or a feeling of pressure in the throat.
Other indications for thyroid surgery are
- a malignant thyroid tumor
- "cold" nodules that are disturbing due to their size, grow quickly or suggest malignancy,
- "hot" nodules that cause hyperthyroidism, which can only be treated inadequately with medication and radioiodine therapy.
- Graves' disease, if radioiodine treatment is not appropriate or not desired.
Symptoms and various diseases of the thyroid gland © Henrie | AdobeStock
Most thyroid operations are performed under general anesthesia and take around one to two hours.
Thyroid surgery is performed via a small incision (4-5 cm) below the neck (known as a collar incision). The surgeon then exposes the thyroid gland and removes diseased tissue.
The amount of tissue to be removed depends on whether it is a single nodule or the size of a possible malignant tumor. Occasionally, an entire thyroid lobe or the entire thyroid gland has to be removed. In the case of thyroid cancer, the entire thyroid gland, including the surrounding lymph nodes, is usually removed.
If a malignant tumor is suspected, the removed tissue is examined during the procedure(frozen section examination). If there is no evidence of malignancy, a further detailed histological examination is carried out after the thyroid operation. This means that it is only possible to determine with certainty whether thyroid cancer is present or not a few days after the operation.
During thyroid surgery, care is taken to protect the vocal cord nerves and the parathyroid glands.
Before the wound is closed, a drainage tube is inserted to allow blood and wound secretions to drain away. The wound is usually closed using self-dissolving stitches and a cosmetically inconspicuous suturing method.
Like any operation, thyroid surgery also involves risks. In addition, the vocal cord nerves and parathyroid glands may be injured. However, these complications only occur in a very small proportion of patients.
If the parathyroid glands have been injured or removed during thyroid surgery, the patient must be given calcium and vitamin D tablets after the thyroid operation. However, the parathyroid glands can be reimplanted elsewhere in the body (e.g. neck muscles).
The thyroid gland is one of the organs with the best blood supply. Therefore, post-operative bleeding can occur immediately after thyroid surgery. Patients should therefore remain under inpatient observation for at least 24 hours after thyroid surgery.
In around 0.5 percent of patients, one or both vocal cord nerves are permanently paralyzed after the procedure (recurrent paresis). In around 3 percent, only temporary paralysis occurs.
The risk to the vocal cord nerves during thyroid surgery is related to their particular proximity to the thyroid gland. A vocal cord nerve runs along the back of each thyroid lobe. Swelling or bruising in the surgical area can temporarily irritate these nerves after thyroid surgery. However, permanent paralysis is also possible due to strain, pressure or an incision.
Irritation of the nerves can lead to
- a change in voice quality
- hoarseness
- considerable problems when speaking
can occur. If the nerves have only been irritated, the voice impairment usually passes six to twelve weeks after thyroid surgery. In exceptional cases, it can take a year for normalization to occur.
If the vocal cord nerves are permanently damaged, the impairment can be treated with speech training (speech therapy).
As a rule, the duration of hospitalization for thyroid surgery is two to three days. Patients can get up the day after thyroid surgery and are allowed to drink and eat.
The wound drains (tubes for draining blood and secretions) are removed on the first or second day after the thyroid operation. The skin sutures follow on the fifth to seventh day, unless self-dissolving sutures were used. In most cases, the vocal cord function is also checked by an ear, nose and throat specialist.
Five to seven days after discharge from hospital, patients can usually resume all their usual activities.
Four to six weeks after the thyroid operation, the metabolic status is checked by taking a blood sample. The doctor then decides whether and in what quantity thyroid hormones should be administered.
After the complete removal of the thyroid gland, a lifelong intake of thyroid hormones is required. Accordingly, the hormone level should be checked regularly.
If thyroid tissue has been left in place, an additional dose of iodine is recommended, depending on the size of the remaining thyroid gland. This can counteract renewed enlargement or nodule formation.
If the operation was performed due to thyroid cancer, radioiodine therapy is usually followed four to six weeks later. The exception is medullary thyroid carcinoma, which does not absorb radioiodine.
After thyroid surgery, the tumor markers in the blood are checked and a scintigraphy is carried out to monitor them.
The wound should be protected with a plaster immediately after thyroid surgery. You can even take a shower the day after thyroid surgery. However, bathing should be avoided for about two weeks after thyroid surgery.
One week after the thyroid operation, the wound has healed to such an extent that a plaster is no longer required. However, there may still be slight swelling and redness at this point.
In the three months following the thyroid operation, the scar should be protected from sunlight. Sauna sessions, perfume, chlorine or salt water are not recommended during this period.
