The thyroid gland is located in the front portion of the neck and makes a hormone called thyroxine, or T4. This hormone plays an integral role in the development and growth of children. Any disorder that affects this gland, interferes with its development or prevents production of T4 can have a devastating effect on the health and development of children. Infant thyroid problems may develop before or after birth, with some requiring lifelong treatment.
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Congenital hypothyroidism, a condition that causes the body to produce inadequate levels of thyroid hormone, affects about one in every 4,000 newborns, according to the Texas Department of State Health Services. Some infants develop a transient form of hypothyroidism that disappears during childhood, explains Children's Hospital Boston. Hyperthyroidism, or an overactive thyroid gland, is rare in infants and typically occurs only if the mother developed the condition before or during her pregnancy.
The Texas Department of State Health Services explains that symptoms of thyroid problems in infants are often subtle and may go undiagnosed without testing. In cases of hypothyroidism, infants may exhibit pale or blotchy skin, show little interest in eating, become frequently constipated, and have low blood pressure, a slow heart rate or cold hands and feet. Growth may be slow, with many hypothyroid infants showing poor weight gain and growth beginning in late infancy. Some infants may appear lethargic, cry infrequently and feel floppy when picked up. Over time, signs of intellectual disability, an enlarged tongue and coarse facial features may appear, explains Merck.
Hyperthyroidism in infants causes a high metabolic rate, rapid breathing and heart rate, excessive hunger, irritability and poor weight gain. Some infants develop bulging eyes. Merck warns that hyperthyroidism may interfere with breathing, or cause heart failure and death.
The most common cause of thyroid problems in infants is improper growth of the thyroid gland during pregnancy. Some babies are born without a thyroid gland, and some thyroid problems stem from understimulation of the thyroid by the pituitary gland. In other cases, the thyroid gland itself is not damaged or underdeveloped, but it still fails to produce enough thyroid hormone. Transient hypothyroidism usually develops in response to maternal antithyroid medications or iodine deficiency during pregnancy.
Hyperthyroidism generally occurs when the mother produces antibodies during the pregnancy that stimulate the thyroid gland to make extra thyroid hormone. These antibodies affect the baby's thyroid after crossing the placenta.
Most states require newborns to undergo a simple blood test following after birth to check for indications of a thyroid disorder. If the results of this test show a problem, or if your infant's doctor suspects a thyroid problem, your baby will need to see a pediatric endocrinologist for additional testing.
A thyroid uptake test uses radioactive iodine isotopes to show how well the gland is working, and a bone age X-ray can show the lack of bone maturity commonly associated with thyroid disorders in infants. A TRH stimulation test can help detect low levels of pituitary TSH to determine if too little pituitary stimulation is affecting your baby's thyroid. Elevated levels of thyroid-stimulating antibodies and thyroid hormone can confirm a diagnosis of hyperthyroidism.
Doctors treat hypothyroidism with daily doses of synthetic thyroid hormone. The synthetic hormone behaves identically to natural thyroid hormone in the body and causes no side effects when administered at proper doses. This medication is available in a tablet form that can be dissolved or crushed for infants. Hyperthyroidism is treated with medications that slow thyroid hormone production in the body. Treatment is only necessary until the mother's antibodies disappear from the baby's blood.