Thyroid disease can affect anyone at any age, including children and newborns. Hormones produced by the thyroid (the small, butterfly-shaped gland in the front of the neck) help your child grow and develop normally, and regulate your child’s heart rate, blood pressure, metabolism, energy level and more.

If your child’s thyroid gland is underactive, meaning it does not make enough thyroid hormone, it’s called hypothyroidism. This is the most common thyroid disorder in children. Another type of thyroid condition, hyperthyroidism (also known as Graves’ disease) occurs from an overactive thyroid.

Hypothyroidism can be present at birth (congenital) or can be acquired any time during childhood or adulthood. Babies may be born with congenital hypothyroidism if the thyroid gland doesn’t develop properly. A test for this condition is usually part of the routine newborn screening performed in the hospital about 24 hours after your baby is born.

Acquired hypothyroidism in children and teens is most commonly caused by an autoimmune reaction in which the immune system attacks the thyroid gland, called chronic lymphocytic thyroiditis (CLT), also known as Hashimoto’s thyroiditis.

Acquired hypothyroidism is more common in girls than in boys and usually occurs during late childhood or adolescence. Certain children are at greater risk, including those with a family history of autoimmune disease, type 1 diabetes or Down syndrome. It may also occur in children who’ve had surgery, radiation or other damage to the thyroid or pituitary gland.Too much or too little iodine in the diet can lead to hypothyroidism.

The signs of hypothyroidism in children are usually subtle and gradual, so the condition can sometimes go undetected for years. A child with an underactive thyroid may experience:

• Poor growth
• Shorter height
• Fatigue (tiredness)
• Weight gain
• Constipation
• Sensitivity to cold temperatures
• Dry skin and brittle hair, hair loss
• Puffy face, hoarse voice, enlarged thyroid gland (goiter)
• Exercise intolerance
• Slow heart rate
• Permanent teeth that develop later
• Delayed puberty
• Heavy or irregular periods (in girls)
• Increased testicular size (in boys)

Sometimes acquired hypothyroidism is suspected if your child’s growth chart starts to show poor linear growth (height to weight ratio), meaning your child is getting bigger but not taller.

Sometimes parents wonder if their child’s weight gain is due to a thyroid problem, but being overweight is rarely caused by a sluggish thyroid (usually it’s the other way around).

Addressing the condition as early as possible is important, as hypothyroidism can impair your child’s normal growth and development, and delay puberty.

To diagnose the condition, your child’s doctor may order a blood test that measures T4 (thyroid hormone) and TSH (thyroid-stimulating hormone made by the pituitary gland) levels. When TSH levels are high and T4 levels are low, it could signal hypothyroidism.

Your child’s doctor may refer you to a pediatric endocrinologist who may prescribe a daily pill of synthetic thyroid hormone called levothyroxine (Synthroid^®). Your child will then need repeat bloodwork to check her/his check thyroid levels and customize the dose.

While hypothyroidism tends to be a lifelong condition, thyroid hormone replacement is an effective treatment. Some children will need to take hormones for life, while others may outgrow the disorder.

With proper treatment, most children can reach their normal height, achieve normal growth and development, and live a normal, healthy life.

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