What is Congenital Hypothyroidism?
Congenital hypothyroidism is a loss of thyroid function that affects infants
at birth. The condition is due to the failure of the thyroid gland to develop
correctly during pregnancy—sometimes the thyroid gland is absent. As
a result, the infant does not have enough thyroid hormone after birth. This
may result in abnormal growth and development, as well as slower mental function.
In fact, congenital hypothyroidism is one of the most common, preventable
causes of mental retardation.
How is Congenital Hypothyroidism Diagnosed?
Infants in the United States are tested for the disorder as newborns. State
public health programs perform these screening tests to detect some genetic
diseases for which early diagnosis and treatment are available. Although
the states vary in what tests they perform, all 50 states test for congenital
hypothyroidism. The test is done when the newborn is between 24 and 72 hours
The reason the test is done so early is that infants with congenital hypothyroidism
usually appear normal at birth and may not show any signs or symptoms of
the condition until they are several months old. Blood for the screening
test is obtained from the infant's heel and is placed on a piece of filter
paper. The laboratory measures the infant’s level of thyroid hormone and thyroid
stimulating hormone. If these tests indicate hypothyroidism,
the infant’s pediatrician is contacted immediately so treatment can
begin without delay. It is likely that the blood tests will be repeated to
confirm the diagnosis.
The pediatrician may also take an x-ray of the legs to look at the ends of
the bones. In infants with congenital hypothyroidism, the bones have an immature
appearance, which also helps to confirm the diagnosis. A scan of the thyroid may also be done to determine the location, or absence of the thyroid gland.
How is Congenital Hypothyroidism Treated?
If congenital hypothyroidism is treated within the first month of life, the
child can grow and develop normally. If congenital hypothyroidism is not
treated, the infant may develop brain damage, leading to mental retardation
and a delay in normal development.
Symptoms of congenital hypothyroidism are seldom apparent at birth. The age
at which the symptoms appear (and their severity) depends on the function
of the infant’s thyroid gland.
During the first few months of life, symptoms may include poor appetite, choking
while nursing, failure to gain weight and grow, constipation, breathing difficulties,
a hoarse cry, and sluggishness. The infant’s abdomen may be enlarged
and seem to protrude. The skin may feel cold and look mottled, and infant’s
genitals, hands, and feet may be swollen.
Congenital hypothyroidism is treated with thyroid hormone replacement. An
infant treated for the condition within the first month of life can expect
to grow and develop normally. Treatment must be continued for life.
The infant will require frequent visits to the doctor for blood tests. These
may be done weekly until laboratory values show normal thyroid levels. Once
the levels are normal, blood tests will become less frequent, generally every
2 - 3 months, for the first three years. Successful treatment depends on
life long daily medication with close follow up of thyroid hormone levels.
Taking medication on a routine basis needs to become a part of the child’s
lifestyle assure optimal growth and development.