Evaluatie van de Quantase R Phenylalanine bepaling en het Millipore Multiscreen Assay System als methode voor de screening van pasgeborenen op PKU

The Quantase R Phenylalanine Assay, an enzymatic/colorimetric method for the determination of phenylalanine (Phe) in dried bloodspots, was evaluated for the neonatal screening on PKU. The within run variation (N=12) for bloodspot samples with 0.15, 0.29 and 0.53 mmol/l was 10%, 5% and 5%, respectively. The between run variation (N=56) for bloodspot samples with 0.38 and 0.96 mmol/l was 9% and 8%, respectively. The mean concentration and standarddeviation in 33630 bloodspot samples was 0.077 +- 0.025 mmol/l (%CV=32%). The measured Phe-concentration was elevated (>=0.24 mmol/l) in 13 samples (0.039%). Reanalysis of these samples, in the same bloodspots, revealed a Phe-concentration of