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Sometimes certain treatments for childhood cancer can affect the thyroid gland.
This damage is usually very easy to treat.
Signs and symptoms may not show up for years after treatment.
The thyroid gland is located in the lower part of the neck in front of the trachea, also known as the windpipe.
The gland produces 2 hormones: triiodothyronine (T3) and thyroxine (T4). These hormones play an important role in:
The pituitary gland makes thyroid stimulating hormone (TSH). It releases TSH in response to the levels of T3 and T4 in the blood.
If the levels are low, the pituitary gland makes more TSH to increase the production of thyroid hormones. If T3 and T4 levels are high, the pituitary makes less TSH to signal the thyroid gland to slow down production.
People who received radiation to areas affecting the thyroid and/or pituitary glands are at risk for thyroid problems. The risk of thyroid problems increases with increasing dose of radiation.
These areas include:
Other treatments that may affect thyroid function include:
Other factors may include being:
Thyroid problems may occur soon after radiation but generally do not occur until several years later.
Problems that may occur:
Hypothyroidism is the most common thyroid problem in childhood cancer survivors.
It occurs when the thyroid is not active enough. Thyroid hormone levels are low and body’s metabolism slows down.
Three types of hypothyroidism occur in childhood cancer survivors:
All types of hypothyroidism are treated with daily thyroid pills. Treatment is usually for life. In some cases of compensated hypothyroidism, treatment may be stopped if the thyroid gland begins to work normally.
Symptoms of hyperthyroidism may include:
Hyperthyroidism may be treated with:
Treatment for hyperthyroidism may result in hypothyroidism. It is then treated with a daily thyroid pill.
Treatment involves surgery. The surgeon may remove a part of the thyroid or the whole thyroid in addition to affected lymph nodes in the neck. Treatment with radioactive iodine (I-131) may be necessary to destroy remaining thyroid tissue. After treatment, most people will need to take daily thyroid hormone replacement pills.
Ask your oncologist about your risks of developing late effects.
Inform your primary health care provider about your risks. Share a copy of your Survivorship Care Plan, which includes a treatment summary. The summary includes details about your cancer treatment and information about health problems that may occur because of treatment.
Survivors should have yearly check-ups with a health care provider.
The check-up should include evaluation of growth in children and teens, examination of the thyroid gland, and a blood test to measure the levels of TSH and T4.
During periods of rapid growth, health care providers may recommend more frequent monitoring of thyroid levels.
If problems with thyroid levels are identified, health care providers may refer survivors to an endocrinologist. If a lump is detected on the thyroid, survivors may be referred to a surgeon or other specialist.
Female survivors at risk for thyroid problems who are planning to become pregnant should have their thyroid function checked before attempting pregnancy.
Expectant mothers with thyroid disease have a higher chance of having babies with developmental problems.
It is also important to monitor thyroid levels periodically during pregnancy.
Reviewed: November 2019