In hypothyroidism, the thyroid gland produces fewer hormones than the body needs. As a result, symptoms such as fatigue, depressed moods, weight gain, and feeling cold may occur. The cause of the symptoms is often the autoimmune disease Hashimoto’s thyroiditis. In most cases, hypothyroidism can be treated well with artificially produced hormones – however, the medication usually has to be taken for the rest of the patient’s life.
Hypothyroidism – what is it?
The thyroid gland is an organ that produces the hormones triiodothyronine and thyroxine, which are vital for us humans. These are important for our circulation, metabolism, growth, and psychological well-being, among other things. If there is a deficiency of thyroid hormones, the metabolism works more slowly and performance decreases. The production and release of thyroid hormones is controlled in the brain by the hypothalamus and the pituitary gland. These produce hormones that stimulate thyroid activity. If these control centers in the brain or the thyroid gland itself no longer function properly, fewer hormones are produced than the body needs. In such a case, one speaks of hypothyroidism. Hypothyroidism occurs relatively often. In Germany, between 0.5 and 1 percent of the population is affected. Women suffer from the disorder significantly more often than men. The risk of hypothyroidism increases with age.
Causes of hypothyroidism
There can be several causes behind hypothyroidism. The problems can either be in the thyroid gland itself or originate from the hypothalamus or pituitary gland. In addition, hypothyroidism may also be triggered by medical procedures, such as those performed to treat hyperthyroidism. In rare cases, hypothyroidism can be caused by a diet low in iodine. It is also rare for hypothyroidism to be congenital – this is the case in about one in 4,000 children. In contrast to this congenital form, hypothyroidism with a different cause is called acquired hypothyroidism. If a physical disease is the cause, three different forms are distinguished:
- Primary hypothyroidism: in this form, there is a dysfunction of the thyroid gland.
- Secondary hypothyroidism: In this form, the hormone production in the pituitary gland is disturbed.
- Tertiary hypothyroidism: In this form, hormone production in the hypothalamus is disturbed.
Thyroiditis (Hashimoto’s thyroiditis).
Hypothyroidism in adults is most often caused by chronic thyroiditis. The cause of the inflammation is usually the autoimmune disease Hashimoto’s thyroiditis. In this disease, which primarily affects women between the ages of 40 and 50, the body mistakenly recognizes the thyroid gland as foreign tissue and produces antibodies against the organ. This results in chronic inflammation, which partially destroys the tissue of the thyroid gland. Over time, this results in hypothyroidism.
Disease of the hypothalamus and pituitary gland.
That hypothyroidism is caused by diseases of the regulatory centers in the brain is relatively rare. If there is a disorder of the pituitary gland – for example, due to a tumor – it produces too little of the hormone TSH (thyrotropin or thyroid-stimulating hormone). The hormone ensures that hormone production in the thyroid gland is stimulated. If the TSH concentration is too low, not enough thyroid hormones are produced in the thyroid gland. Hypothyroidism can be caused not only by disease of the pituitary gland, but also of the hypothalamus. The hypothalamus produces the neurotransmitter TRH (thyroliberin or thyrotropin-releasing hormone). This in turn stimulates the formation and release of TSH in the pituitary gland. If there is a disease of the hypothalamus, this thus indirectly affects thyroid function.
Medical measures as a cause of hypothyroidism
In the case of hyperthyroidism, the medical measures used to treat the disorder may eventually trigger hypothyroidism.These measures include, for example, radioiodine therapy and surgical removal of parts or all of the thyroid gland. If too much tissue is destroyed or removed, the thyroid gland can no longer produce enough hormones. In addition, too high a dose of thyrostatic drugs can also lead to hypothyroidism. These drugs are used in hyperthyroidism to inhibit hormone production in the thyroid gland.
Congenital hypothyroidism
Congenital hypothyroidism occurs relatively rarely. However, because early detection is crucial in this form, screening is performed on all newborn infants in Germany. This involves measuring the concentration of the hormone TSH in the blood. Only if hypothyroidism is detected in time can permanent damage to the nervous system be prevented. There can be various causes behind congenital hypothyroidism. It is possible, for example, that the thyroid gland is completely missing, that the thyroid tissue has not developed properly or that hormone production is disturbed. In addition, the child’s thyroid gland may have been damaged in the womb – for example, by a diet low in iodine or radioiodine therapy during pregnancy. In the case of hypothyroidism, symptoms such as reduced activity as well as weakness in drinking typically become noticeable in the first months of life. In addition, neonatal jaundice may last longer than usual. If the dysfunction is not detected in time, it can lead to developmental disorders of the nervous system and bones. In such a case, it is called cretinism.
