Under-activity of thyroid gland can happen because of a wide variety of factors. The causes of Hypothyroidism include:
- Autoimmune Thyroiditis: When the body starts attacking its own cells, the phenomenon is called autoimmunity. When such a situation arises in the thyroid gland and causes hypothyroidism, it is called autoimmune thyroiditis or Hashimoto's thyroiditis, which is one of the commonest causes of Hypothyroidism.
- Surgery / Radiation of Thyroid Gland: Certain conditions like cancer of thyroid, thyroid nodules and goiter may be subjected to surgery or radiation therapy. Post such procedures, the functioning of the gland may be hampered leading to hypothyroidism.
- Conventional treatment for Hyperthyroidism: People suffering from Hyperthyroidism are often treated with radioactive iodine or anti-thyroid medications to normalize their thyroid function. This can sometimes go overboard and cause hypothyroidism.
- Medications for other diseases: Drugs like Amiodarone, Lithium, Interferon-Alpha inhibit the production of thyroid hormones and figure prominently as one of the causes of Hypothyroidism.
- Pituitary abnormalities: Diseases of the pituitary including tumors, as well as pituitary surgery can affect TSH secretion, and in turn decrease secretion of thyroid hormones.
- Iodine deficiency: This is amongst the most preventable causes of Hypothyroidism. Iodine is essential for the synthesis of thyroid hormones and inadequate iodine will lead to inadequate hormone production.