Measurement of serum aipha-fetoprotein in early infancy: Utilization of dried blood specimens

Abstract

Serum alpha-fetoprotein (AFP) concentrations were measured in dried blood spots and the biologic half-life of AFP was deter¬mined during the first month after parturition. AFP blood levels, in babies at all birthweight groups during the first wk, were partitioned according to birthweight and sex. A synthetic surge of serum AFP at postnatal day 3 was observed in babies of the low birthweight category (<6 lb 8 oz), whereas a concomitant surge could not be demonstrated in babies of medium, (6 lb 8 oz to 8 lb 8 oz), and high birthweight, (>8 lb 8 oz), categories. All babies weighing less than 6 lb 8 oz, regardless of prematurity likewise displayed the synthetic surge. The sex of the infant appeared to have no influence on AFP serum concentrations. In a population of infants ranging in age from 1-30 days, the biologic apparent half-life of AFP was calculated as 5.7 days; however, the half-life of AFP was found to differ among the three groups of infants when subdivided by birthweight and was higher (7.7 days) in babies of low birthweight. Our determination of 2 S.D. cutoff values for AFP in the first wk of life should prompt further studies in which the relationship of AFP to newborn disorders should be more fully explored. © 1983 International Pediatric Research Foundation, Inc.