Causes
Primary hypothyroidism is the most common cause. In this form of hypothyroidism, the problem lies in the thyroid gland itself. The triggers for this can either be congenital or acquired.
In Germany, approximately one in 4000 newborns is born with hypothyroidism. The organ is either completely absent, incorrectly developed or the thyroid gland has a disrupted hormone production due to a genetic defect. An overly high dose of medication can also trigger an underactive thyroid in the newborn if the mother has an overactive thyroid during pregnancy.
Acquired primary hypothyroidism occurs with increasing age and is usually the result of a permanent inflammation of the thyroid tissue. The underlying disease is called Hashimoto’s thyroiditis. This is an autoimmune disease of unknown origin.
In this case, the body produces proteins directed against the body’s own tissue, so-called antibodies, which falsely recognize the thyroid tissue as foreign, attack and destroy it. The destruction of the functioning thyroid cells ends in an underactive thyroid. Another cause of hypothyroidism can be caused as a complication by medical treatment with drugs, radiotherapy or surgical correction of hyperthyroidism, in which too much of the hormones are produced and the body runs permanently at full speed.
A cause of hypothyroidism that has become very rare in our country is iodine deficiency. To synthesize the already mentioned hormones T3 and T4, the thyroid gland needs iodine as a building block. In our latitudes, the trace element iodine is often added to food, so that deficiency symptoms can be avoided through food alone.If the cause of hypothyroidism does not lie in the organ itself, but in the control centers of the thyroid gland, which are located in our brain, we speak of secondary or tertiary hypothyroidism.
Damage to these brain structures can be caused by injuries, tumors, surgical interventions or radiotherapy in the head area. The hormones produced in the brain centers are sent from the brain to the thyroid gland via the bloodstream and normally control the production and distribution of thyroid hormones. A disturbance in their synthesis leads to the defective production of T3 and T4 in the thyroid gland.
The result is an underactive thyroid. When an infant is diagnosed with hypothyroidism, it can have various causes. The thyroid gland is not created or not present (athyreosis), the thyroid gland is maldeveloped (thyroid dysplasia) or is not in its physiological, normal anatomical position, which limits its function (thyroidectopia). Very rare causes of congenital hypothyroidism are faulty thyroid hormone production or resistance (= insensitivity) of the cells to the hormones, so that they do not react adequately to the hormonal signals.
