Thyroid surgery. Part or all of the thyroid
gland may be removed to treat disorders such as having too much thyroid hormone
(hyperthyroidism), an enlarged thyroid gland (goiter) that makes swallowing difficult, thyroid
thyroid nodules that may be overactive or cancerous.
Hypothyroidism results when the thyroid gland is removed or when remaining
thyroid tissue does not function properly.
therapy, which is often used to treat hyperthyroidism. Radioactive iodine
therapy can destroy the thyroid gland, leading to
External beam radiation, which is used to treat
some cancers, such as
Hodgkin's lymphoma. This radiation treatment can
destroy the thyroid gland.
Less common causes include:
Infections. Viral and bacterial infections can
temporarily damage the thyroid gland. This causes a short-term form of the
condition. Hypothyroidism caused by infection usually does not result in
In rare cases, disorders of the
pituitary gland or the
hypothalamus (secondary and tertiary forms of
hypothyroidism). The pituitary gland and hypothalamus produce hormones that
control the thyroid and, as a result, affect its ability to produce thyroid
Excessive iodine, which, in food or medicines, can reduce
the function of the thyroid gland. This is usually
Congenital hypothyroidism. In rare cases, an infant is
born without a properly functioning thyroid gland. All children born in a
hospital in the U.S. are tested at birth for hypothyroidism.