부산대학교 도서관

The present study aims at evaluating the diagnostic efficacy of an enzyme-based colorimetric method (Enzolve's kit) for quantitative determination of phenylalanine in comparison to the gold standard tandem mass spectrometer (MS/MS). This study was conducted on 155 neonates aged 3-7 days attending the neurometabolic clinic of Cairo University Children Hospital as a part of the neonatal screening program. Samples of patients were selected according to their phenylalanine levels obtained by MS/MS. Group 1 included 49 normal neonates with phenylalanine level <150 μmol/L. Group 2 included 106 phenylketonuria (PKU)-affected neonates with phenylalanine level >150 μmol/L selected to cover the analytical range of the commercial kit. Blood samples on filter paper cards were reassayed by an enzyme-based colorimetric test kit. On correlating the phenylalanine level assayed using enzyme-based colorimetric technique using Enzolve kit and MS/MS technique, r = 0.83 and P < 0.01 were found. Also it yielded a regression equation; phenylalanine level assayed using Enzolve kit = (30.6 + 0.98 × phenylalanine level assayed using MS/MS). Upon detecting positive PKU cases using Enzolve's kit at a phenylalanine cutoff level of 127 μmol/L and by MS/MS technique at a cutoff level of 150 μmol/L, a statistically significantly association ( P = 0.000) and an agreement with kappa of 0.64 ( P = 0.000) were produced. On constructing ROC curve for assay of phenylalanine using Enzolve's kit, an area under the curve of 0.963 was found. The Enzolve kit is a simple ,cost-effective, rapid with an accepted overall accuracy test that can be used preliminary to the use of the more sophisticated and expensive MS/MS in screening as well as monitoring patients with PKU. [ABSTRACT FROM AUTHOR]