The high cases of hypothyroidism (roughly 95% or more) are caused by thyroid gland. A much smaller number of cases (roughly 5% or less) are caused by other problems in the brain or pituitary gland, a small gland located beneath the brain.
The causes of hypothyroidism include:
* A condition called Hashimoto's thyroiditis
* Treatment of hyperthyroidism
* Treatment of thyroid tumors
* Radiation
* Interference from drugs
* Subacute thyroiditis
* Postpartum thyroiditis
* Problems in the pituitary gland