Abstract
BACKGROUND: The use of dried blood spots (DBS) for the assay of lysosomal enzymes has facilitated the implementation of pilot studies for newborn screening for lysosomal storage disorders in various developed countries. The aim of the study was to determine the influence of ambient temperature during DBS preparation and storage on lysosomal enzyme activity in a developing, tropical country. METHODS: Blood samples from 12 healthy subjects collected on a S&S 903 filter paper were dried and stored at different temperatures for different periods of time. Activities of five lysosomal enzymes (acid α-glucosidase, acid α-galactosidase, acid β-glucocerebrosidase, acid sphingomyelinase, and galactocerebrosidase) were determined by tandem mass spectrometric and fluorimetric (acid α-glucosidase and acid β-glucocerebrosidase only) assays. RESULTS: The mean activities of all five enzymes decreased significantly when DBS was dried at temperatures above 24°C (P<.0001). DBS stored at 4°C, 24°C, 30°C, 37°C, and 45°C for 10 days and more, also showed significant reduction in activities of all five enzymes (P<.0001). CONCLUSION: The results highlight the importance of maintaining the correct ambient temperature during DBS preparation and storage to avoid false positive results when screening for lysosomal storage disorders.