Hypothyroidism is a condition in which the thyroid gland is underactive and produces an insufficient amount of thyroid hormones. Hypothyroidism is the most common thyroid disorder affecting children. However, children with the disorder display different symptoms from adults. Hypothyroidism in the newborn, when left untreated, can lead to intellectual disability and profound developmental delays.
What causes hypothyroidism?
The most common cause of hypothyroidism is an autoimmune reaction in which the body's immune system slowly destroys the thyroid gland. Maternal antibodies produced against a woman's thyroid, or treatment of a mother's thyroid disorder (such as iodine), can affect her unborn child's thyroid function.
What are the symptoms of hypothyroidism?
The symptoms of hypothyroidism in children are different than in adults. The following are the late symptoms of the disorder. However, each child may experience symptoms differently, and often the symptoms are not seen at all. This is why all newborn infants should be screened for low thyroid function.
Congenital hypothyroidism is associated with an increased risk for congenital abnormalities of the cardiovascular, genitourinary, and skeletal systems.
Late symptoms in newborns (neonatal hypothyroidism):
- Jaundice (yellowing of the skin, eyes, and mucous membranes)
- Hoarse cry
- Poor appetite
- Umbilical hernia (navel protrudes out)
- Slow bone growth
Childhood (juvenile hypothyroidism) symptoms:
- Slow growth, sometimes resulting in abnormally short limbs
- Delayed tooth development
Adolescents (adolescent hypothyroidism) symptoms:
- Slow growth
- Delayed puberty
- Hoarse voice
- Slow speech
- Droopy eyelids
- Puffy and swollen face
- Hair loss
- Dry skin
- Slow pulse
- Weight gain
The symptoms of hypothyroidism may resemble other conditions or medical problems. Always consult your child's doctor for a diagnosis.
How is hypothyroidism diagnosed?
Congenital (present at birth) hypothyroidism is usually detected during the routine newborn screening. Blood samples taken may reveal abnormally low levels of T4 (the main hormone released from the thyroid or abnormally high levels of thyroid-stimulating hormone (TSH), suggesting thyroid problems. Released from the brain, TSH is the hormone that increases the size, number, and activity of the thyroid cells. TSH also stimulates the release of hormones that affect a person's metabolism and that are essential for normal growth and development. Evaluation may include a scan of the thyroid gland to check for abnormalities.
How is hypothyroidism treated?
Specific treatment for hypothyroidism will be determined by your child's doctor in consultation with you. Considerations include your child's current and past health status, age, medication tolerance, projected disease progression, and your beliefs and attitudes about the treatment alternatives.
Left untreated in newborns, hypothyroidism can lead to intellectual disability. Untreated hypothyroidism may also lead to anemia, low body temperature, and heart failure. The goal of treatment is to restore the thyroid gland to normal function, producing normal levels of thyroid hormones.
Treatment may include prescription of thyroid hormones to replace the deficient hormones. Some children will require hormone replacement therapy for the rest of their lives, while others appear to outgrow the disorder, often by the age of three. Regular monitoring of the child's thyroid hormone levels during the course of treatment, including a 30-day discontinuation of treatment to see how the thyroid responds, can help your child's doctor diagnose your child's condition more accurately.
What is congenital hypothyroidism?
Congenital hypothyroidism (CH) means the disorder is present at birth. CH is one of the most common and preventable causes of intellectual disability. Children born in the U.S. are tested for the disorder during their standard newborn screening. Newborn screening is performed in newborns in state public health programs to detect certain genetic diseases for which early diagnosis and treatment are available. Approximately one out of every 4,000 newborns is diagnosed with CH each year.
Most children born with CH appear normal at birth, usually because the maternal thyroid hormones have sustained the fetus in the womb. Significant signs that the infant may have hypothyroidism are low T4 (thyroxine, a hormone secreted by the thyroid gland that regulates metabolism) levels and high TSH levels in the blood. Some infants with CH will have low T4 levels, but normal TSH levels.