The Effect of Underlying Neuropsychiatric Conditions on Blood Levels of GFAP and UCH-L1 in Children

While ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) and glial fibrillary acidic protein (GFAP) have demonstrated clinical relevance in evaluating traumatic brain injury (TBI), less is known about how underlying pediatric neurological or psychiatric diagnoses may influence baseline biomarker levels. Plasma samples from a pediatric biobank were analyzed for UCH-L1 and GFAP concentrations. Eligible participants were <19 years of age and had a documented diagnosis of attention-deficit/hyperactivity disorder, anxiety, depression, or seizure disorder but no recent history of trauma, infectious illness, or other chronic medical conditions. Biomarker levels were compared (1) across diagnostic categories, (2) with a separate group of historic controls ( n = 216), and (3) with adult thresholds used to guide head CT use in mild TBI (UCH-L1 400 pg/mL; GFAP 35 pg/mL). Among 88 participants (median age 15 years), UCH-L1 and GFAP values remained relatively stable across conditions. There were no significant differences between diagnostic groups or compared with controls. Approximately 6.8% of children had GFAP levels above the adult threshold, whereas <3% exceeded the UCH-L1 threshold. Underlying neuropsychiatric conditions do not appear to meaningfully modify baseline circulating GFAP or UCH-L1 levels in children, suggesting that these conditions may not preclude the use of these biomarkers in the evaluation of pediatric TBI.