In hypothyroidism, the thyroid produces fewer hormones than the body needs. As a result, symptoms such as tiredness, depressive moods, weight gain and a feeling of cold may occur. Cause of the complaints is often the autoimmune disease Hashimoto's thyroiditis. Mostly, hypothyroidism can be treated well by man-made hormones - however, the drugs usually need to be taken for a lifetime.
Hypothyroidism - What is it?
The thyroid is an organ that produces the vital hormones triiodothyronine and thyroxine that are vital to us humans. Among other things, these are important for our circulation, our metabolism, our growth and our psychological well-being. If there is a deficiency of thyroid hormones, the metabolism works more slowly and the performance drops.
The production and release of thyroid hormones in the brain is controlled by the hypothalamus and pituitary gland. These produce hormones that stimulate the activity of the thyroid gland. If these centers of regulation in the brain or the thyroid gland itself are no longer functioning properly, fewer hormones are produced than the body needs. In such a case one speaks of a hypothyroidism.
Hypothyroidism is relatively common. In Germany, between 0.5 and 1 percent of the population are affected. Women are significantly more likely to suffer from the disorder than men. With age, the risk of hypothyroidism increases.
Causes of hypothyroidism
Behind hypothyroidism can hide various causes. The problems can be either in the thyroid itself or from the hypothalamus or pituitary gland. In addition, it may also happen that a hypofunction is triggered by medical measures that are performed, for example, in the treatment of hyperthyroidism.
In rare cases, hypothyroidism can be caused by a low-iodine diet. It is also rare that an inferior function is innate - this is the case with one in 4, 000 children. In contrast to this congenital form, a subfunction with a cause other than acquired hypothyroidism is called.
If a physical illness is the cause, three different forms are distinguished:
- Primary hypothyroidism: In this form, there is a thyroid dysfunction.
- Secondary hypothyroidism: In this form, hormone production in the pituitary gland is disturbed.
- Tertiary hypothyroidism: In this form, hormone production in the hypothalamus is disturbed.
Thyroiditis (Hashimoto's thyroiditis)
Thyroid hypofunction is most commonly caused in adults by chronic thyroiditis. The cause of the inflammation is usually the autoimmune disease Hashimoto's thyroiditis.
In this condition, which primarily affects women between the ages of 40 and 50, the body falsely identifies the thyroid gland as foreign tissue and produces antibodies against the organ. The result is a chronic inflammation, through which the tissue of the thyroid gland is partially destroyed. Over time, this creates a hypothyroid function.
Hypothalamic and pituitary disease
That hypothyroidism is triggered by diseases of the control centers in the brain is relatively rare. If there is a pituitary (pituitary gland) disorder, for example due to a tumor, it will produce too little TSH. The hormone ensures that hormone production in the thyroid gland is stimulated. If the TSH concentration is too low, insufficient thyroid hormones will be produced in the thyroid gland.
Hyperthyroidism can be caused not only by pituitary disease but also by the hypothalamus. The hypothalamus produces the messenger TRH. This in turn stimulates the formation and release of TSH in the pituitary gland. If there is a disease of the hypothalamus, this also indirectly affects the thyroid function.
4 facts about hypothyroidism - © istockphoto, ChesiireCat
In case of hyperthyroidism, the medical measures used to treat the disorder may trigger hypothyroidism. These measures include, for example, radioiodine therapy and surgical removal of parts or the entire thyroid gland. If too much tissue is destroyed or removed, the thyroid can not produce enough hormones.
In addition, high-dose antithyroid drugs may also lead to hypofunction. These drugs are used in hyperthyroidism to inhibit hormone production in the thyroid gland.
Congenital hypothyroidism is relatively rare. However, as early detection is of crucial importance in this form, all newborn children in Germany are screened. The concentration of the hormone TSH in the blood is measured. Because only if the hypothyroidism is recognized in time, lasting damage to the nervous system can be prevented.
There are various causes behind congenital hypothyroidism. It is possible, for example, that the thyroid is completely absent, that the thyroid tissue has not developed properly or that the hormone production is disturbed. In addition, the thyroid of the child in the womb may have been damaged - for example, by a low-iodine diet or radioiodine therapy during pregnancy.
Underactive thyroid glands typically show signs of decreased activity and dehydration during the first few 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 the bones. In such a case, cretinism is used.