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Neonatal hypothyroidism detected by the Northwest Regional Screening Program
Insights
The Northwest Regional Screening Program effectively detects congenital hypothyroidism in newborns using thyroxine (T4) and thyroid-stimulating hormone (TSH) tests. This screening identifies infants needing timely treatment, improving outcomes for neonatal hypothyroidism.
Area of Science:
- Pediatrics
- Endocrinology
- Public Health
Background:
- Congenital hypothyroidism (CH) is a critical condition requiring early detection and treatment to prevent developmental issues.
- Neonatal screening programs are vital for identifying CH in asymptomatic infants.
- The Northwest Regional Screening Program was established to screen infants in Oregon, Montana, Alaska, and Idaho.
Purpose of the Study:
- To evaluate the effectiveness and efficiency of the Northwest Regional Screening Program for congenital hypothyroidism.
- To determine the incidence of primary hypothyroidism and thyroxine-binding globulin deficiency in the screened population.
- To assess the diagnostic approach and associated costs.
Main Methods:
- Utilized dried blood filter paper specimens collected from newborns in four states.
- Implemented a two-tiered screening strategy: initial thyroxine (T4) measurement followed by thyroid-stimulating hormone (TSH) testing for low T4 values.
- Confirmed diagnoses with serum samples via venipuncture.
Main Results:
- Detected 25 cases of primary hypothyroidism (1:4,430) and 14 cases of thyroxine-binding globulin deficiency (1:7,900) in 110,667 infants.
- Achieved a low repeat specimen request rate (0.4% in Oregon, 0.05% in other states) with the T4/TSH approach.
- Identified common etiologies including thyroid aplasia, ectopic gland, hypoplasia, and goiter.
Conclusions:
- The screening program successfully identified infants with congenital hypothyroidism, many lacking clinical signs.
- The T4 followed by TSH testing strategy is efficient and cost-effective for neonatal screening.
- Early diagnosis and treatment, ideally by one month of age, are achievable and crucial for infant prognosis.
Abstract:
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 test consist of an initial thyroxine (T4) measurement; a thyroid-stimulating hormore (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 amont 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 request 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 goiter. 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.