Effect of Sample Processing Delays on the Values of Serum Based Biomarkers of Brain Injury Collected from the Umbilical Cord Blood of Neonates

Background: When a neonate is born with suspected brain injury, blood samples are often obtained from the umbilical cord blood but are not always processed immediately. Objective: Test the accuracy of brain injury biomarker assays on samples that experienced delayed processing. Methods: Healthy neonates who did not have risk factors for brain injury provided cord blood samples. Group 1 blood samples were centrifuged immediately, and the serum was removed and frozen at baseline, 4, and 8 hours. Group 2 had a baseline sample processed immediately and then blood samples remained in contact with the clotted portion until 4, and 8 hours and then were centrifuged. Enzyme-linked immunosorbent assays determined the concentrations of Ubiquitin C-Terminal Hydrolase L1 (UCH-L1) and Glial Fibrillary Acidic Protein (GFAP). Results: Group 1’s average concentrations of GFAP were 62±47 pg/ml at 0 hours (n=32) with a mean increase of 3±14% and a decrease of 0.2±9% at 4 and 8 hours, respectively. UCH-L1 average concentrations were 3306±3093 pg/ml at 0 hours (n=37) with a mean increase of 3±10% at 4 hours and a mean decrease of 0.6±11% at 8 hours. Group 2’s average GFAP concentrations were 104±111 pg/ml at 0 hours (n=9) with a mean decrease of 5±9% and 7±7% at 4 and 8 hours, respectively. UCH-L1 average concentrations were 3448±2456 pg/ml at 0 hour (n=8) with a mean increase of 9±6% and 6±18% at 4 and 8 hours, respectively. Conclusion: Delays in processing up to 8 hours did not significantly affect the concentration of UCH-L1 or GFAP.