The stability of hexacosanoyl lysophosphatidylcholine in dried-blood spot quality control materials for X-linked adrenoleukodystrophy newborn screening

Abstract

Objectives: Newborn screening for X-linked adrenoleukodystrophy utilizes tandem mass spectrometry to analyze dried-blood spot specimens. Quality control materials (dried-blood spots enriched with hexacosanoyl lysophosphatidylcholine) were prepared and stored at different temperatures for up to 518. days to evaluate the stability of this biomarker for X-linked adrenoleukodystrophy. Design and methods: Dried-blood spot storage included desiccant (45, 171, and 518. days) or omitted desiccant (53. days at >. 90% relative humidity). Specimens were stored for 171 and 518. days at -. 20. °C, 4. °C, ambient temperature, and 37. °C. Each weekday for 45. days, a bag of specimens stored at 4. °C was warmed to ambient temperature and one specimen was removed for storage at -. 80. °C. Specimens were analyzed by high-performance liquid-chromatography electrospray ionization tandem mass spectrometry and data was plotted as concentration (micromoles per liter) vs. time. Linear regression provided slope and y-intercept values for each storage condition. Results: Small slope values (0.01 or less) and y-intercept values close to the enrichment indicated less than 11% loss of hexacosanoyl lysophosphatidylcholine under all storage conditions tested. Conclusions: Quality control materials for X-linked adrenoleukodystrophy are stable for at least 1. year when stored with desiccant.