The thyroid gland is a butterfly-shaped endocrine gland that is located in the lower front of the neck, just above the collarbone. The thyroid’s job is to make thyroid hormones, which are released into the blood and then carried to every tissue in the body. In children, thyroid hormone helps to ensure that growth and development occur normally and that the body’s energy, metabolism, heart, muscles, and other organs are working properly.
Hypothyroidism is thyroid hormone deficiency.
In children, hypothyroidism can be present at birth (a condition called congenital hypothyroidism) or it can develop later in childhood. When the thyroid gland stops working despite being normal in the newborn period it is called ‘acquired’ hypothyroidism.
Causes of Hypothyroidism in Children
The most common cause of hypothyroidism in children is a family history of the disease. Children whose parents, grandparents, or siblings have hypothyroidism are at a higher risk for thyroid disease. This is also true if there’s a family history of immune problems that impact the thyroid.
Autoimmune conditions, such as Graves’ disease or Hashimoto’s thyroiditis, more commonly appear during puberty. These thyroid conditions more frequently affect girls than boys.
Other common causes of hypothyroidism in children include:
- not enough iodine in a child’s diet
- being born with a nonfunctional thyroid or without a thyroid gland (also called congenital hypothyroidism)
- improper treatment of a mother’s thyroid disease during pregnancy
- abnormal pituitary gland
Symptoms of hypothyroidism
There are no signs or symptoms that are unique to hypothyroidism. Also, because the condition can develop slowly over many years, the symptoms may be less noticeable or ignored.
- Two important symptoms in children are:
- Slowing of height – an important early sign of hypothyroidism in children and
- Pubertal development that may be delayed in adolescents.
An important finding on physical exam is an enlarged thyroid, also called a goiter
Other hypothyroid symptoms may include:
- Fatigue (being more tired than expected)
- Increased sensitivity to cold
- Dry skin
- Dry and brittle hair (more in the shower, on brush, clothing and bedding)
- Irregular and/or heavy menstrual periods
- Weight gain. Hypothyroidism can slow metabolism, but most people do not gain excess weight only because of low thyroid hormone.
Because the symptoms are so variable and nonspecific (may be caused by things other than the thyroid), the only way to know for sure whether a child or teenager has hypothyroidism is to perform a blood test.
How to Diagnosis?
The diagnosis of hypothyroidism is made with a blood test for two hormones:
- TSH (thyroid-stimulating hormone) is the most sensitive test for hypothyroidism. TSH is made in the pituitary, a gland at the base of the brain that controls our hormone system. If the thyroid gland is not working, the pituitary releases more TSH to try to get the thyroid to make more thyroid hormones (T3 and T4). Less commonly, the thyroid may be normal and it is the pituitary that cannot make enough TSH. This is called ‘central’ hypothyroidism and may be caused by medications, illness, a brain injury or a mass/tumor near the pituitary.
- T4 levels measure the amount of the thyroid hormone thyroxine (T4) that is in the blood. Often this test will measure the level of “free T4” (abbreviated FT4). FT4 is the form that is not attached to a protein and can enter and affect the body’s cells.
- Thyroid auto-antibodies – the immune system makes antibodies against thyroid proteins (called thyroid peroxidase or TPO) and the antibody levels may be measured to confirm the diagnosis of Hashimoto’s. Many patients who have thyroid autoantibodies continue to have normal thyroid hormone levels. In this situation, it may be hard to predict if and/or when the person will need thyroid medication.