Transient Association Between Elevated NSE and Reduced fT3 Levels Following Mild Traumatic Brain Injury: A 12-Month...

Background/Objectives: In recent years, the perception of mild traumatic brain injury (mTBI) has significantly changed, which implies the need to revise the approach towards post-injury monitoring. Since post-concussion symptoms may overlap with manifestations of neuroendocrine dysfunction, we investigated whether thyroid hormone measurements may provide complementary information to neuron-specific enolase (NSE), a commonly used biomarker of neuronal injury by assessing the association between NSE and thyroid hormone levels following mTBI and to explore potential neuroendocrine alterations during a 12-month follow-up period. Methods: We conducted a prospective cohort study. Participants, adults aged ≥18 years with mTBI meeting the inclusion criteria, were recruited from a tertiary trauma center emergency department (ED) in northern Poland from January 2023 to October 2025. During their post-head injury admission to the ED, patients had a blood sample taken and were asked to complete online questionnaires. The procedure was repeated after 3, 6 and 12 months. The NSE, pituitary and thyroid hormones were measured using a chemiluminescence immunoassay method (CLIA). The questionnaires used in the study were: Rivermead Post-Concussion Symptoms Questionnaire (RPQ), Hospital Anxiety and Depression Scale (HADS) and Pittsburgh Sleep Quality Index (PSQI) and the Polish validation of EQ-5D-5L. Results: Higher NSE levels were associated with lower fT3 levels at 3 months post injury. No significant association was found at 6- and 12-month follow up. Conclusions: In patients with persistently elevated NSE levels three months after mTBI, reduced fT3 concentrations were observed. Although exploratory, these findings suggest a potential link between neuronal injury biomarkers and post-traumatic neuroendocrine responses, supporting further investigation of multi-marker approaches for post-mTBI monitoring.