Extended storage of whole blood with 3-deazaadenosine for homocysteine assay

Background To assess the effectiveness of using 3-deazaadenosine (3DAA) to maintain plasma homocysteine concentrations (tHCy) in whole blood samples. Methods Blood was obtained from five volunteers and samples were maintained at room temperature, in cold packs or in a fridge (0-40 degrees C) with and without 3DAA. At time points ranging from 6 to 168 h, samples were processed and analysed for tHCy using the Abbott IMx system. Results There was a mean increase in tHCy of 29.4% at 6 h increasing to 242.6% after 168 h in whole blood kept at room temperature. There was no significant change in tHCy for 48 h when stored in cold packs, and for 72 h when stored in the fridge. The addition of 3DAA had a significant preservative effect (P < 0.001), maintaining tHCy to 48 h in whole blood at room temperature, 120 h in the fridge and 96 h in cool packs. There was no statistical difference in results obtained from samples containing preservative and controls when using the Abbott IMx system. Conclusion 3DAA is an effective preservative of tHCy in whole blood, particularly in samples maintained at 0-4 degrees C.