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Causes of hypothyroidism

The thyroid gland located in the front of the neck just below the voice box (larynx) is responsible for the release of thyroid hormones.

Following are the causes of hypothyroidism

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Autoimmune or Hashimoto's thyroiditis: Inflammation of the thyroid gland is the most common cause of hypothyroidism. This inflammation is most commonly caused by Autoimmune or Hashimoto's thyroiditis, in which the immune system attacks the thyroid gland and damages the cells of the gland.

Postpartum thyroiditis: After pregnancy, some women develop hypothyroidism which is commonly known as postpartum thyroiditis.

Few other common causes of hypothyroidism are:

Congenital (birth) defects: Research establishes that one out of every 4,000 babies is born without a properly functioning thyroid gland.

Due to radiation: Radiation treatments to the neck to treat different types of cancers, may also damage the thyroid gland. 

Radiation to the brain also lead to hypothyroidism

Radioactive iodine: Radioactive iodine used to treat an overactive thyroid (hyperthyroidism) cause hypothyroidism.

Viral thyroiditis: Viral thyroiditis, which may cause hyperthyroidism, and is often followed by temporary or permanent hypothyroidism. This condition is also known as Sub acute Thyroiditis as it occurs due to the inflammation of the thyroid gland after a viral disease. The sub acute thyroiditis is further classified as: sub acute granulomatous, lymphocytic thyroiditis; and postpartum thyroiditis.

Sub acute granulomatus: Sub acute granulomatus is characterized by neck pain and tenderness. Some patients experience difficulty swallowing or fever. Typically it starts with a period of hyperthyroidism lasting for four to six weeks, thereafter the thyroid hormone levels become normal for about four weeks. However, it does not stop at it and further declines toward a hypothyroid phase, which lasts for about four to six weeks.

Lymphocytic thyroiditis: Inflammation of the thyroid gland caused by a particular type of white blood cell known as a lymphocyte is known as Lymphocytic thyroiditis. This condition appears commonly after pregnancy.

Postpartum thyroiditis: Postpartum thyroiditis condition develops within one to six months following delivery. It is characterized by initial stages of hyperthyroid phase. However, this hyperthyroid phase is usually associated with significant damage to the thyroid as a consequence of the inflammation. As a result the hyperthyroid phase is followed by the development of hypothyroidism.

Sheehan syndrome: Sheehan syndrome, which is caused when a woman bleeds severely during pregnancy or childbirth resulting in the destruction of the pituitary gland.

Pituitary and hypothalamic disease: Pituitary and hypothalamic disease affects the amount of thyroid hormone made and secreted by the thyroid gland and causes hypothyroidism. Secondary hypothyroidism is the condition of hypothyroidism caused pituitary disease, while tertiary hypothyroidism is caused by hypothalamic disease.

Iodine deficiency:  Severe form of Iodine deficiency also causes hypothyroidismin mountainous areas of poor, less industrialized nations.

Surgical removal of part or all of the thyroid gland in order to treat other forms of thyroid problems.

Drugs that cause hypothyroidism are:
  • Amiodarone (Cordarone), a medication used for the treatment for irregular heart beat;
  • Medications used for treating hyperthyroidism (overactive thyroid), like propylthiouracil (PTU) and methimazole; and 
  • Lithium (Eskalith, Lithobid), used for preventing manic as well as depressive attacks.

Next page: Diet for Hypothyrodism

Written by: Healthplus24 team
Date last updated: July 31, 2012