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Congenital hypothyroidism (CH) means the disorder is present at birth. CH is one of the most common, preventable causes of mental retardation. Children in the US 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 1,400 infants per 5,000,000 newborns are diagnosed with CH shortly after birth each year.
In about 10 percent cases, congenital hypothyroidism is inherited by an autosomal recessive gene, which means that two copies of the gene are necessary to produce the condition and both males and females are equally affected.
Most children born with CH appear normal at birth, possibly because the maternal thyroid hormones have sustained the infant's normal thyroid function in the womb. However, a significant sign that the infant may have hypothyroidism are low T4 (thyroxine, a hormone secreted by the thyroid gland which regulates metabolism) levels and high TSH (thyroid-stimulating hormone, a hormone that helps to increase the size, number, and activity of the thyroid cells; stimulates the release of hormones that affect a person's metabolism and that are essential for normal growth and development) levels (greater than 40 mU/L). However, researchers have found that some infants with CH will have low T4 levels, but normal TSH levels.
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