charged from the hospital, and repeated four to six weeks later. Immediately after birth, thyroxine levels are considerably higher in the infant than in adults. By the end of the first week, thyroxine levels decrease significantly. Low thyroxine levels in an infant's blood indicate a need for additional tests to clarify the diagnosis. A complete thyroid workup including tests for triiodothyronine, thyroxine-binding globulin, and free thyroxine levels is necessary to confirm a diagnosis of congenital hypothyroidism before treatment can begin.
Because hypothyroidism is a fairly common disorder and can be successfully treated with hormone replacement therapy, screening for congenital hypothyroidism is common in many countries (Leger, 1998). In France, screening began in the late 1970s using the measurement of serum thyroid stimulating hormone (TSH) in an eluate of whole blood collected on filter paper when the babies are three days old. The experience in France has been that early diagnosis and treatment prevents most of the serious problems of cong
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