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

Abstract

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. Test the accuracy of brain injury biomarker assays on samples that experienced delayed processing. 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). 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. Delays in processing up to 8 hours did not significantly affect the concentration of UCH-L1 or GFAP.