Low Thyroid Function in Teens

Hypothyroidism is more common in adults, but it can also occur in teens 3. With hypothyroidism, the thyroid gland in the front of the neck fails to produce enough thyroid hormones 3. Because thyroid hormones influence growth, development and puberty, teens with reduced thyroid hormones can have signs and symptoms related to these processes. Symptoms of low thyroid function in teens are often vague, but it's important to spot them because simple treatment can help prevent long-term problems.

Causes and Risk Factors

Hypothyroidism is more common in girls than boys 3. Hypothyroidism in teens is most often caused by Hashimoto thyroiditis, an autoimmune disorder in which the immune system mistakenly attacks the thyroid gland 3. Teens with other autoimmune diseases, such as type 1 diabetes, or a family history of autoimmune hypothyroidism have increased risk of developing the condition 3. Teenagers with certain genetic conditions, including Down syndrome, are also at increased risk. Other causes of hypothyroidism include side effects from certain medications and problems with the hypothalamus or pituitary gland 3. Less common causes of hypothyroidism include iodine deficiency, exposure to pesticides or chemicals, radiation therapy, thyroid surgery or viral illness 3.

Unique Signs and Symptoms

Undiagnosed hypothyroidism in children and teens often causes problems with growth and development 3. While teens with hypothyroidism often gain weight, their growth rate can slow, and they may be shorter than expected and look young for their age 3. Untreated hypothyroidism can also delay puberty 3. Boys may have increased testicle size, and girls may not develop breasts or start menstruating. If the hypothyroidism develops after a teenage girl has started menstruating, she may experience heavy or irregular bleeding 3. Low thyroid function can also lead to mood and behavioral problems in teens, as well as difficulties with school performance.

Other Signs and Symptoms

In teens with early hypothyroidism, symptoms can be subtle and difficult to spot 3. But as metabolism slows, the lack of thyroid hormones affects multiple body systems with signs and symptoms that mirror those of hypothyroidism in adults, including:
-- Fatigue, sluggishness, depression, difficulty concentrating and forgetfulness 3. -- Cold sensitivity, dry skin and brittle hair and nails. -- Constipation and weight gain. -- Facial puffiness, hoarseness and thyroid gland enlargement. -- Muscle and joint pain and stiffness.

Diagnosis and Treatment

Blood tests are used to diagnose hypothyroidism, focusing on the thyroid hormone called thyroxine, or T4, and thyroid-stimulating hormone, or TSH 3. The pituitary gland produces TSH to stimulate the thyroid to release hormones. With hypothyroidism, the pituitary gland produces large amounts of TSH in a futile attempt to stimulate the thyroid to produce adequate amounts of thyroid hormones 3. So people with hypothyroidism have high TSH and low T4 levels 3.

Hypothyroidism is treated with a daily dose of synthetic thyroid replacement hormone, which alleviates symptoms over time 3. Frequent blood tests may be needed initially to adjust the medication dosage. Thereafter, testing is done periodically -- often yearly -- to be sure the dosage is still appropriate.

Warnings and Precautions

If your teen experiences any signs or symptoms that may indicate low thyroid function, make an appointment to see your healthcare provider to determine the cause of your youngster's symptoms.

For teens being treated for hypothyroidism, call the doctor between checkups if symptoms are not improving or getting worse 3. Too much medication can cause chest pain, an irregular heartbeat or weight loss -- and potential long-term problems, including osteoporosis. Different brands of thyroid medications sometimes work differently, so check with your teen's doctor if the pharmacy changes the medication brand.

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