The Northwest Regional Screening Program to detect congenital hypothyroidism in infants born in Oregon, Montana, Alaska, and Idaho (combined birthrate of 69,000/yr) was added to our ongoing screening program in 1975. The program utilizes dried blood filter paper specimens collected routinely in the first few days of life in all four states and again at about 6 weeks of age in Oregon only. The screening tests consist of an initial thyroxine (T4) measurement; a thyroid-stimulating hormone (TSH) determination is performed on those specimens with T4 concentrations in the lowest 3% group. Serum samples obtained by venipuncture are requested for confirmation of the diagnosis. In the first two years of the program, 25 infants with primary hypothyroidism were detected among 110,667 infants screened, a frequency of 1:4,430. Fourteen cases of thyroxine-binding globulin deficiency were also detected, a frequency of 1:7,900. Using the T4 followed by TSH testing approach, the frequency of requests for repeat specimens was 0.4% in Oregon and 0.05% in the other states. The cost per specimen was $1.96. The majority of infants lacked clinical signs or symptoms of hypothyroidism; only one infant was clinically suspected of having hypothyroidism prior to detection. The most common neonatal symptoms were constipation, lethargy, and prolonged jaundice, while the most common physical signs were hypotonia, umbilical hernia, and large fontanels. Thyroid scans showed the most common etiology to be thyroid aplasia, followed by an ectopic gland, hypoplasia, and goitèr. Serum T4 concentrations were lowest in those infants with aplasia, intermediate in infants with an ectopic gland or hypoplasia, and normal in the infant with the goiter. Neonatal hypothyroidism varies in degree and has several different causes; the capacity to secrete thyroid hormone, the duration before hypothyroidism becomes clinically manifest, and possibly the eventual prognosis for intellectual function depend on the nature of the underlying cause. While the mean age at treatment was 59 days, the goal of diagnosing congenital hypothyroidism and treating affected infants by 1 month of age seems realistic.
A screening program for the detection of neonatal hypothyroidism has been in effect in Oregon since May 1975. Blood samples are obtained from all newborn infants to test for phenylketonuria and other metabolic diseases. A second specimen is obtained from more than 90% of these infants who are retested at 4 to 6 weeks of age. These Guthrie filter paper blood samples are analyzed for thyroxine (T4), and all samples with a low T4 value are analyzed for thyroid stimulating hormone (TSH). At the outset of the program, it was speculated that the screening might detect infants who had reduced