Do you have hypothyroidism and how is it caused?

Do you have hypothyroidism and how is it caused?

Hypothyroidism: where does it come from?

As with many diseases and disorders, the causes of hypothyroidism do not all come from a specific source. Most cases of hypothyroidism (the underactive thyroid) are caused by problems that begin in the thyroid.

These cases are called primary hypothyroidism. Secondary hypothyroidism is caused by problems affecting the pituitary gland, while tertiary hypothyroidism develops due to problems occurring in the hypothalamus. To understand the causes of hypothyroidism, the first step is to divide it into the three types of hypothyroidism – primary, secondary and tertiary.

Hashimoto's thyroiditis is the most common cause of primary hypothyroidism. Hashimoto's is an autoimmune disease in which the body's immune system begins to attack the thyroid gland, preventing it from producing the proper amount of hormones. To combat this disease, the thyroid tries to work even harder, often resulting in an enlargement of the thyroid gland - medically known as a goiter.

Another, less common cause of hypothyroidism is an adverse reaction to radioactive ablation therapy. This type of therapy is commonly given to patients who have been diagnosed with hyperthyroidism or who have recently received surgical treatment for thyroid cancer. It is estimated that 80-90% of patients undergoing this therapy develop hypothyroidism within 2 to 3 months.

Other thyroid diseases derived from primary hypothyroidism include subacute, silent, and postpartum thyroiditis.

• Subakute Thyreoiditis: Verursacht durch eine Virusinfektion, die das Immunsystem veranlasst, eine große Menge an Lymphozyten (Blutzellen, die die Immunantwort auf ein Virus bestimmen) freizusetzen. Diese Lymphozyten greifen das Schilddrüsengewebe an, was entweder zu einer vorübergehenden oder dauerhaften Hypothyreose führt.
• Stille Thyreoiditis: Verursacht durch eine Autoimmunerkrankung, bei der das Immunsystem Lymphozyten freisetzt, die in die Follikel der Schilddrüse eindringen. In diesem Fall wird auch die Schilddrüse angegriffen, was zu Unteraktivität und entweder vorübergehender oder dauerhafter Hypothyreose führt.
• Postpartale Thyreoiditis: Zwischen 6 und 8 % der Frauen entwickeln Symptome einer Hyperthyreose gefolgt von einer Hypothyreose 6 Wochen bis 6 Monate nach der Geburt. In vielen Fällen normalisiert sich die Schilddrüse nach einem Jahr wieder, in anderen Fällen kommt es zu einer dauerhaften Hypothyreose.

In rare cases, primary hypothyroidism may be the result of radiation exposure to the neck, certain medications that affect thyroid hormone production, or iodine deficiency. Since the thyroid relies on iodine to function properly, a deficiency of this mineral can lead to Thyroid problems. Due to the fact that most foods in the United States are fortified with iodine, this deficiency is almost exclusively reserved for underdeveloped countries.

Secondary hypothyroidism is less common, but is typically caused by damage to the pituitary gland from radiation, surgery, or a tumor.

• Hypopituitarismus ist die Abnahme der Sekretion eines oder mehrerer Hormone, die von der Hypophyse produziert werden, während Panhypopituitarismus die vollständige Erschöpfung der gesamten Hormonproduktion durch die Hypophyse ist. Da diese Drüse der Schilddrüse sagt, was sie tun soll, beeinflusst eine Veränderung der Hormonproduktion der Hypophyse auch die Hormonproduktion der Schilddrüse.
• Das Sheehan-Syndrom entwickelt sich typischerweise nach der Schwangerschaft aufgrund von niedrigem Blutdruck. Dieses Syndrom verursacht eine postpartale Hypophysenhypophyse, die entweder zu einer vorübergehenden oder dauerhaften sekundären Hypothyreose führen kann.
• Die Entwicklung von Hypophysentumoren kann auch die Hormonproduktion der Hypophyse beeinträchtigen, was wiederum zu einer Fehlfunktion der Schilddrüse führt, die zu einer Hypothyreose führt.

The third, least common hypothyroidism is tertiary hypothyroidism, which is typically caused by dysfunction of the hypothalamus. This part of the brain is responsible for telling the pituitary gland what to do and how many hormones to produce. When this part of the brain is negatively affected by a disorder, both the pituitary and thyroid are affected.

Although each of these three types of thyroid disease is caused by different factors, the symptoms of thyroid problems remain the same regardless of which subtype of hypothyroidism you have.

However, the symptoms of thyroid disease differ between hypothyroidism and hyperthyroidism (overactive thyroid), so it's important to understand the differences between the two when determining which type of thyroid disease you have.

Understanding the causes of hypothyroidism is one of the first steps to better understanding your body and getting better treatment. The more you know, the better informed you will be when making treatment decisions.

Inspired by Claire Christina Rathausky