Causes for Hypothyroidism

Hypothyroidism may be caused by several reasons.

Hypothyroidism may be caused by several reasons. The causes are broadly divided into primary and secondary causes. 

Primary causes of hypothyroidism: They refer to the conditions directly affecting the thyroid gland and causing it to make low levels of thyroid hormones. Primary causes of hypothyroidism are far more common than secondary causes. They include:

• Hashimoto’s thyroiditis: It is the most common of the primary causes. It is an autoimmune condition in which the body’s immune system attacks and damages the thyroid. The damage prevents the gland from making and releasing adequate thyroid hormones.
• Thyroiditis: It is the inflammation of the thyroid gland.  Thyroiditis is commonly caused by an autoimmune attack or by a viral infection. This may cause the thyroid to release its entire supply of stored thyroid hormone into the blood at once, causing transient hyperthyroidism (excessive amounts of thyroid hormones in the blood) followed by hypothyroidism.
• Congenital hypothyroidism: This type of hypothyroidism is present at birth. The baby may be born without a thyroid, a partly formed thyroid, non-functional thyroid hormones, or a thyroid in the wrong place (ectopic thyroid)
• Surgical removal of part or all of the thyroid: It may be done due to cancer or non-cancer swellings of the thyroid and other conditions.
• Radiation treatment of the thyroid: radiation due to conditions such as certain diseases of the thyroid or cancers of the head and neck region may damage the thyroid gland.
• Certain medicines: Some medications such as amiodarone, lithium, interferon-alpha, and interleukin-2 can prevent adequate thyroid hormone production. 
• Excess or deficiency of iodine: Iodine is needed for making thyroid hormones. Too much or too little iodine in the diet can cause hypothyroidism.

Secondary causes: This refers to the conditions that cause the pituitary gland to fail. This means that the pituitary gland cannot send the thyroid-stimulating hormone (TSH) to the thyroid gland to make and release the thyroid hormones normally. The pituitary gland may be damaged by tumor, radiation, or surgery.

The thyroid gland is a small butterfly-shaped endocrine gland (a gland that secretes a substance called a hormone into the bloodstream). It is normally located in the lower part of the front of the neck. It makes the thyroid hormones, which are released into the blood and then carried to various body parts. Thyroid hormones are needed for the body to use energy, maintain body temperature, and keep the brain, heart, muscles, and other organs working properly. Hypothyroidism is a medical condition in which the thyroid gland becomes underactive. The gland is not able to make enough thyroid hormone to keep the body functioning normally. Lab investigations show that people with hypothyroidism have low thyroid hormone levels in their blood. Some of the common causes of this condition are autoimmune diseases, such as Hashimoto’s thyroiditis, surgical removal of the thyroid, and radiation treatment. Hypothyroidism is a common condition affecting around 4.6% of the U.S. population ages 12 and older.

Women are more likely to get hypothyroidism after menopause than earlier in life. Hypothyroidism is a common condition affecting around 4.6% of the U.S. population ages 12 and older. It is particularly common in women over 60 years of age. Hypothyroidism, however, can affect people of all genders, ages and ethnic backgrounds.