Pre-analytical stability of 25-hydroxy vitamin D in human serum

INTRODUCTION: In this study, the effects of pre-analytical storage conditions on 25-hydroxy vitamin D [25(OH)D] samples were examined. The aim was to observe the relative effects of different temperature and time-related storage conditions on the stability of vitamin D.
METHODS: Blood samples from 153 healthy individuals referred to Sakarya Training and Education Hospital polyclinics were stored under different conditions. Serum was obtained by centrifugation and 4 aliquots were stored. One aliquot was analyzed immediately after collection (0-hour sample) and accepted as the reference for the comparison of the other aliquots. Time intervals and different storage conditions for aliquots were categorized as Group 1: 0-hour measurement (n=153), Group 2: 24 hours at 2-8°C (n=153), Group 3: about 2 months at -20°C (n=153), and Group 4: 3 months at -40°C (n=153). Vitamin D analysis was performed using chemiluminescence in the biochemistry laboratory.
RESULTS: There was no statistical difference in 25(OH)D between the 0-hour sample and the 2-8°C, -20°C, or -40°C samples (p=0.462, p=0.958, p=0.063, respectively); 25(OH)D was stable under different storage conditions.
DISCUSSION AND CONCLUSION: Vitamin D is an analyte that is generally not affected by preanalytical variables, and the storage conditions did not affect the acridinium ester magnetic particle chemiluminescence method used.