Children and adolescents can have thyroid issues, which often surprises many parents. The thyroid gland, a small, butterfly-shaped organ at the base of the neck, produces hormones fundamental for a child’s healthy growth, brain development, and metabolism. When this gland produces too little hormone, the condition is called hypothyroidism, resulting in a system-wide slowdown. Conversely, an overactive gland that produces too much hormone leads to hyperthyroidism, which accelerates the body’s processes.
Understanding Pediatric Thyroid Conditions
Pediatric thyroid disorders are categorized by the gland’s function and whether the condition is present at birth or develops later. Hypothyroidism, an underactive thyroid, is the more common type in children. The most severe form is Congenital Hypothyroidism (CH), affecting approximately 1 in every 2,000 to 4,000 newborns. CH occurs when the thyroid gland fails to develop or function properly while the baby is still in the womb.
Because thyroid hormone is important for early brain development, untreated CH can lead to intellectual impairment. To prevent this, mandated newborn screening programs test every infant for CH shortly after birth. This screening detects most cases, allowing immediate treatment that is effective in preventing severe developmental problems.
Acquired hypothyroidism typically develops later in childhood or adolescence. The most frequent cause is the autoimmune disorder Hashimoto’s thyroiditis. In this condition, the immune system mistakenly produces antibodies that attack the thyroid gland, causing inflammation and gradual damage that reduces hormone output. This damage leads to an underactive thyroid, though some children may initially develop a goiter, which is an enlargement of the gland.
Hyperthyroidism, or an overactive thyroid, is much less common but is still a serious condition. The vast majority of pediatric hyperthyroidism cases are caused by Graves’ disease, also an autoimmune disorder. In Graves’ disease, the immune system creates an antibody called thyroid-stimulating immunoglobulin (TSI) that causes thyroid cells to produce an excessive amount of hormone. This overstimulation leads to thyrotoxicosis, where the body’s metabolism runs too fast.
Thyroid nodules and thyroid cancer can also affect children, though they are less frequent than functional disorders. Thyroid nodules, or lumps on the gland, occur in about 1% to 2% of the pediatric population. Although rare, pediatric thyroid nodules carry a much higher risk of malignancy—up to 26%—compared to the 5% to 10% risk seen in adults. The most common type of thyroid cancer in children is papillary thyroid cancer.
Recognizing Symptoms by Age Group
The signs of a thyroid disorder can be subtle and vary depending on the child’s age and the condition type. For infants with congenital hypothyroidism, symptoms are often mild or absent at birth, emphasizing the value of mandatory newborn screening. When symptoms appear, they are typically non-specific and may include prolonged jaundice (yellowing of the skin and eyes). Other signs include poor feeding, excessive sleepiness, and constipation.
More distinctive signs of severe hypothyroidism in an infant include a hoarse cry or a puffy face. The baby may also exhibit poor muscle tone (hypotonia). If left undiagnosed, the infant’s growth will slow, and developmental milestones may be delayed.
In older children and adolescents, acquired hypothyroidism (Hashimoto’s) reflects a general slowing of the body’s systems. A primary sign is a reduction in growth velocity, leading to a slowed increase in height. They may experience unexplained weight gain, chronic fatigue, and poor school performance due to difficulty concentrating.
Physical symptoms often include dry skin, coarse hair, and increased sensitivity to cold temperatures. For adolescent girls, hypothyroidism can lead to menstrual irregularities, such as heavy or prolonged periods. The child may also complain of chronic constipation and sluggishness.
Conversely, hyperthyroidism (Graves’ disease) causes symptoms related to an overstimulated system. These children often experience a rapid or irregular heart rate, sometimes felt as palpitations. Behavioral changes are common, including increased nervousness, anxiety, and hyperactivity.
Despite eating more, children with hyperthyroidism frequently lose weight or fail to gain weight due to their accelerated metabolism. Other physical signs include a fine tremor in the hands, difficulty sleeping, and heat intolerance. In some cases of Graves’ disease, Graves’ ophthalmopathy can cause the eyes to appear prominent or bulging.
Screening Tests and Treatment Options
Diagnosis often begins with the universal newborn screening process. This involves a simple heel-prick blood test performed a few days after birth, which measures levels of Thyroid-Stimulating Hormone (TSH) and sometimes T4 (thyroxine). A high TSH level suggests the pituitary gland is working hard to stimulate an underactive thyroid, requiring immediate follow-up testing.
For older children, diagnosis relies on comprehensive blood testing when symptoms are suspected. Primary tests measure TSH, free T4, and free T3 (triiodothyronine) to assess function. If an autoimmune cause is suspected, the doctor will also check for specific antibodies, such as thyroid peroxidase antibodies (TPO) for Hashimoto’s and TSH receptor antibodies (TRAb/TSI) for Graves’ disease.
Imaging tests, such as a thyroid ultrasound, may be used to examine the gland’s size, look for nodules, or assess the increased blood flow characteristic of Graves’ disease. Once a diagnosis is confirmed, treatment focuses on restoring thyroid hormone levels to a normal range.
Treatment for hypothyroidism, whether congenital or acquired, is straightforward and effective. It involves daily hormone replacement therapy using levothyroxine, a synthetic version of T4. For infants, the pill is crushed and mixed with breast milk or formula. Consistent dosing and regular blood monitoring are necessary to ensure the child receives the correct amount of hormone to support normal growth and development.
Managing hyperthyroidism is more complex and typically requires consultation with a pediatric endocrinologist. Initial treatment often involves anti-thyroid medications (ATDs), such as methimazole, which block the thyroid’s ability to produce excess hormone. Because the relapse rate is high, treatment may be required for two years or longer.
If medication is unsuccessful or causes side effects, other definitive options are considered. These include radioactive iodine therapy or surgery to remove part or all of the thyroid gland. These options resolve the hyperthyroidism but result in permanent hypothyroidism, requiring lifelong levothyroxine therapy. The choice between these treatments is individualized, considering the child’s age, disease severity, and family preferences.