Cord blood thyrotropin screening for primary hypothyroidism on Caribbean island: a rapid communication

Screening programs using determinations of serum thyroxine have demonstrated that congenital hypothyroidism occurs in one in 4,000 live births in North America. More than 90 percent of affected infants have primary hypothyroidism with elevated plasma thyrotropin (TSH) levels. Since the feasibility of newborn screening and incidence of congenital hypothyroidism in other less well developed areas of the world is not well defined, a study was undertaken of neonatal primary hypothyroid screening infants born on the Caribbean island of St. Lucia in the Lesser Antilles. Three hundred thirteen cord blood samples were collected on filter paper and transported 3,000 miles to Loyola University of Chicago, Stritch School of Medicine (LUMC). From LUMC, the samples were transported to the Illinois State Metabolic Screening Laboratory for determination of TSH by radioimmunoassay (RIA). In this group of newborns, the mean TSH level in cord blood was 10.23 +/- 0.29 microIU per ml (SEM). It is concluded that screening programs for neonatal primary hypothyroidism can be performed using reference laboratories far removed from the population under observation.