What causes low thyroid?

Hello Anon

Thank you for writing!

An underactive thyroid does not produce the normal level of hormones, which affects metabolism.

Patients with an underactive thyroid will have an elevated level of TSH, as the pituitary gland makes more TSH when thyroid hormones are low. The physician may also use a T4 test and a thyroid autoantibody test to diagnose an underactive thyroid.

The most common cause is inflammation of the thyroid gland. Hashimoto’s thyroiditis is the most common example of this type of inflammation. It occurs when the immune system inappropriately attacks the thyroid gland.

Severe iodine deficiency can also cause hypothyrodism. The thyroid needs iodine to make thyroid hormones so if you’re lacking in it, the thyroid can’t make the required amount.

Other causes are radiotherapy (radiation fired at the neck can damage the thyroid gland) and radiation to the brain. Radioactive iodine or surgery used to treat hyperthyroidism may induce hypothyroidism. Certain medications used to treat depression, psychosis, or heart disease may also result in hypothyroidism.

Sometimes, hypothyroidism is caused by a virus. If this is the case, it may be temporary and you may not need further treatment. In children, hypothyroidism may be caused by a congenital defect, although this is very rare and occurs in only one in 4,000 children.

Hypothyroidism can also be caused by pregnancy.

I hope this helps-

Best,
Susan