Who is likely to develop hypothyroidism?
Women are much more likely than men to develop hypothyroidism. The disease is also
more common among people older than age 60. The American Thyroid Association recommends
that adults, particularly women, have a blood test to detect thyroid problems every
5 years starting at age 35.
Certain factors can increase a person’s chances of developing thyroid disorders.
Individuals may need more regular testing if they
- have had a
thyroid problem before, such as goiter or thyroid surgery
- have a family
history of thyroid disease
- have other
autoimmune diseases including Sjögren’s syndrome, pernicious anemia, type 1 diabetes,
rheumatoid arthritis, or lupus
- have Turner
syndrome, a genetic disorder that affects girls and women
- are older than
- have been pregnant
or delivered a baby within the past 6 months
- have received
radiation to the thyroid or to the neck or chest
Getting tested routinely helps uncover thyroid problems—especially subclinical problems.
Subclinical means a person has no apparent symptoms. Some doctors treat subclinical
hypothyroidism immediately; others prefer to leave it untreated but monitor their
patients for signs that the condition is worsening.
What causes hypothyroidism?
Hypothyroidism has several causes, including
or inflammation of the thyroid gland
hypothyroidism, or hypothyroidism that is present at birth
- surgical removal
of part or all of the thyroid gland
- radiation treatment
of the thyroid
- some medications
Less commonly, hypothyroidism is caused by too much or too little iodine in the
diet or by abnormalities of the pituitary gland.
Hashimoto’s disease, also called chronic lymphocytic thyroiditis, is the most common
cause of hypothyroidism in the
States. Hashimoto’s disease is an autoimmune disorder, which means the body’s immune system,
which normally protects the body by attacking foreign organisms, acts against its
own healthy cells and tissues. In Hashimoto’s disease, the immune system makes antibodies
that attack cells in the thyroid and interfere with their ability to produce thyroid
Thyroiditis causes stored thyroid hormone to leak out of the inflamed thyroid gland.
At first, the leakage raises hormone levels in the blood, leading to hyperthyroidism
that lasts for a month or two. Most people then develop hypothyroidism before the
thyroid is completely healed. Several types of thyroiditis can lead to hypothyroidism:
Subacute thyroiditis. This condition
involves painful inflammation and enlargement of the thyroid. Doctors aren’t sure
what causes subacute thyroiditis, but it may be related to a viral or bacterial
infection. The condition usually goes away on its own in a few months.
Postpartum thyroiditis. Some women
who have been pregnant develop postpartum thyroiditis within a few months of giving
birth. In some women, the thyroid does not heal and their hypothyroidism is permanent.
Postpartum thyroiditis is believed to be an autoimmune condition.
This type of thyroiditis is called “silent” because it is painless, as is postpartum
thyroiditis, even though the thyroid may be enlarged. Silent thyroiditis is probably
an autoimmune condition and sometimes develops into permanent hypothyroidism.
Some babies are born with a thyroid that is not fully developed or does not function
properly. If untreated, congenital hypothyroidism can lead to mental retardation
and growth failure. Most newborns in the
are screened for hypothyroidism, and early treatment can prevent these complications.
Removal of the Thyroid
Part or all of the thyroid gland may be surgically removed as a treatment for
when the thyroid makes too much thyroid hormone
- a large goiter,
which is an enlarged thyroid gland that may cause the neck to appear swollen and
can interfere with normal breathing and swallowing
- thyroid nodules,
which are lumps in the thyroid that can produce excess thyroid hormone
- thyroid cancer
When part of the thyroid is removed, the remaining part may produce normal amounts
of thyroid hormone, but some people who have this surgery develop hypothyroidism.
Removal of the entire thyroid always results in hypothyroidism.
Treatment of the Thyroid
Radioactive iodine, a common treatment for hyperthyroidism, gradually destroys the
cells of the thyroid. Almost everyone who receives radioactive iodine treatment
eventually develops hypothyroidism. People with Hodgkin’s disease, other lymphomas,
and head or neck cancers are treated with radiation, which can also damage the thyroid.
Some drugs can interfere with thyroid hormone production and lead to hypothyroidism.
These drugs include
a heart medication
alpha, a cancer medication
- lithium, a
bipolar disorder medication
a kidney cancer medication
Endocrine and Metabolic Diseases Information Service