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Screening for congenital hypothyroidism: results of screening one million North American infants
Insights
Newborn screening for congenital hypothyroidism in North America has detected 284 infants, with an overall incidence of 1 in 3,684 live births. Early detection and treatment appear to support normal infant development.
Area of Science:
- Endocrinology
- Pediatrics
- Public Health
Background:
- Congenital hypothyroidism (CH) screening programs were initiated in North America in 1972.
- Long-term data from early pilot programs provide insights into CH incidence and outcomes.
Purpose of the Study:
- To report the cumulative findings from the five oldest newborn screening programs for CH in North America.
- To determine the incidence of CH and its subtypes.
- To evaluate the effectiveness of screening in early detection and potential developmental outcomes.
Main Methods:
- Analysis of data from 1,046,362 screened infants across five established North American programs.
- Calculation of incidence rates for primary and secondary-tertiary CH.
- Review of etiological factors for primary CH (glandular aplasia/hypoplasia, normal/enlarged glands, ectopic tissue).
Main Results:
- A total of 284 infants with CH were detected, yielding an overall incidence of 1 in 3,684 live births.
- Primary CH occurred in 246 infants (1 in 4,254 births), with glandular abnormalities being the most common cause.
- Secondary-tertiary CH incidence was 1 in 68,200 births; TBG deficiency incidence was estimated at 1 in 8,913 births.
- Only 8 of 277 detected cases were clinically suspected prior to screening confirmation.
- Screening costs ranged from $0.70 to $1.60 per infant.
Conclusions:
- Newborn screening effectively detects congenital hypothyroidism, often before clinical suspicion.
- Early treatment, as suggested by Quebec data, may lead to normal developmental outcomes.
- The established incidence rates provide valuable epidemiological data for public health planning.
Abstract:
Pilot programs for screening of newborn infants for congenital hypothyroidism began in North America in 1972. To date, the five oldest programs (Quebec, Pittsburgh, Toronto, Oregon Regional, and New England Regional) have screened 1,046,362 infants. A total of 277 infants with congenital hypothyroidism have been detected and seven have been missed, resulting in a total of 284 affected infants in the screened population and an overall incidence of one in 3,684 live births. Of the affected infants, 246 were determined to have primary hypothyroidism, an incidence of one in 4,254 births. Ten infants with secondary-tertiary hypothyroidism were detected in Quebec, Oregon, and Toronto, an incidence of one in 68,200 births. Of all the infants with primary hypothyroidism who were adequately studied, 63% were determined to have aplastic or hypoplastic glands, 14% normal or enlarged glands, and 23% ectopic thyroid tissue. The estimated minimum incidence of infants with TBG deficiency is one in 8,913 births. Only 8 of the 277 detected infants were suspected clinically to have congenital hypothyroidism prior to the time of confirmation of the diagnosis at 4 to 8 weeks of age. The cost of screening varied from $0.70 to $1.60 per infant, depending on which costs were included in the estimate. Preliminary evidence from Quebec suggests that infants treated in the program have normal developmental testing scores at 18 months of age.