OBJECTIVE: To develop a standard preparation for measurement of phenylalanine in blood spots in phenylketonuria against which manufacturers of kits for phenylalanine determination could calibrate their own blood spot calibrators. METHODS: As most of the variation of phenylalanine concentration in dried blood spots is due to the way the blood spot calibrators are prepared, a minimum set of prerequisites for the preparation of blood spot calibrators was established by a group of scientific experts and manufacturers. A "European working standard for phenylalanine in blood spots" (EWS-Phe-01) was prepared and distributed to manufacturers taking part in this project. RESULTS: The control of the homogeneity, linearity, and stability of the EWS-Phe-01 batch gave results within expected ranges. The preliminary results of the recalibration of calibrators for phenylalanine against EWS-Phe-01 by the participating manufacturers were promising; the differences between measurements were much decreased. CONCLUSION: Manufacturers have agreed to use EWS-Phe-01, and since November 1996 EWS-Phe calibrators have been routinely available from these companies. This pilot study may act as a model for minimising discrepancies found in other screening tests.
OBJECTIVE: To develop a standard preparation for measurement of phenylalanine in blood spots in phenylketonuria against which manufacturers of kits for phenylalanine determination could calibrate their own blood spot calibrators. METHODS: As most of the variation of phenylalanine concentration in dried blood spots is due to the way the blood spot calibrators are prepared, a minimum set of prerequisites for the preparation of blood spot calibrators was established by a group of scientific experts and manufacturers. A "European working standard for phenylalanine in blood spots" (EWS-Phe-01) was prepared and distributed to manufacturers taking part in this project. RESULTS: The control of the homogeneity, linearity, and stability of the EWS-Phe-01 batch gave results within expected ranges. The preliminary results of the recalibration of calibrators for phenylalanine against EWS-Phe-01 by the participating manufacturers were promising; the differences between measurements were much decreased. CONCLUSION: Manufacturers have agreed to use EWS-Phe-01, and since November 1996 EWS-Phe calibrators have been routinely available from these companies. This pilot study may act as a model for minimising discrepancies found in other screening tests.
Authors: Stuart J Moat; Danja Schulenburg-Brand; Hugh Lemonde; James R Bonham; Cas W Weykamp; Joanne V Mei; Graham S Shortland; Rachel S Carling Journal: J Inherit Metab Dis Date: 2019-10-02 Impact factor: 4.750