Hypothyroidism or underactive thyroid, is a condition in which thyroid gland does not produce enough of thyroid hormones.

The most common causes of hypothyroidism are iodine deficiency and thyroiditis. Other causes include:

-  Thyroid gland’s damage.

- Virus infections.

-  Immune system disorders (autoimmune thyroiditis).

- Pregnancy (postpartum thyroiditis).

-  Underactive thyroid gland in children (congenital hypothyroidism).

-  Pituitary gland dysfunction.

- Hypothalamic dysfunction.

- Side-effect to certain drugs.

-  Radiation.

After completing a history and physical exam, thyroiditis can be diagnosed with blood tests, including complete blood count, thyroid stimulating hormone (TSH), and free thyroxine (T4).