Jl. Dhondt et al., PREPARATION OF THE FIRST EUROPEAN WORKING STANDARD FOR PHENYLALANINE DETERMINATION IN DRIED BLOOD SPOTS, Journal of medical screening, 5(2), 1998, pp. 63-66
Objective-To develop a standard preparation for measurement of phenyla
lanine in blood spots in phenylketonuria against which manufacturers o
f kits for phenylalanine determination could calibrate their own blood
spot calibrators. Methods-As most of the variation of phenylalanine c
oncentration in dried blood spots is due to the way the blood spot cal
ibrators are prepared, a minimum set of prerequisites for the preparat
ion of blood spot calibrators was established by a group of scientific
experts and manufacturers. A ((European working standard for phenylal
anine in blood spots)) (EWS-Phe-01) was prepared and distributed to ma
nufacturers taking part in this project. Results-The control of the ho
mogeneity, linearity, and stability of the EWS-Phe-01 batch gave resul
ts within expected ranges. The preliminary results of the recalibratio
n of calibrators for phenylalanine against EWS-Phe-01 by the participa
ting manufacturers were promising; the differences between measurement
s were much decreased. Conclusion-Manufacturers have agreed to use EWS
-Phe-01, and since November 1996 EWS-Phe calibrators have been routine
ly available from these companies. This pilot study may act as a model
for minimising discrepancies found in other screening tests.