Commercial radioimmunoassay kit for measurement of alpha-fetoprotein adapted for use with dried blood specimens from newborns.

We adapted a commercial RIA kit to measure alpha-fetoprotein (AFP) in 0.785-microliters portions of 60-microliters spots of dried blood from newborns. We evaluated sample elution, temperature and time stability, between- and within-assay variability, sensitivity, and use of liquid vs dried specimens of blood. Also, we present normal AFP concentrations for healthy neonates during the first postnatal week. Our procedure permits measurement of AFP concentrations both in maternal liquid plasma and in spots of dried blood from the infant with the same RIA kit reagents and standards. The sensitivity, precision, stability, and simplicity of this procedure makes more practical the routine measurement of AFP in dried blood specimens from newborns than measurement in liquid plasma or serum. Blood-sample collection by heel stick suffices for this simple, efficient, inexpensive determination of AFP concentration in the newborn.