This article evaluates whether early serum thyroxine (T4) concentrations predict neurological and psychological outcomes following moderate-to-severe traumatic brain injury (TBI).

This prospective cohort enrolled 56 adults (44 men) with moderate (Glasgow Coma Scale [GCS] 9–12; n = 19) or severe (GCS ≤ 8; n = 37) TBI at a tertiary trauma center. Total T4 and free T4 (fT4) were measured within 10 days of injury, then at 6 and 12 months. Neurological outcome was assessed using Glasgow Outcome Scale-Extended (GOSE); depression and anxiety were evaluated with Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) at 1 year. Multivariable logistic regression examined independent associations between baseline T4 and unfavorable outcome (GOSE ≤ 4), as well as clinically significant depressive (PHQ-9 ≥ 10) or anxiety (GAD-7 ≥ 10) symptoms.

Median baseline fT4 was significantly lower in severe versus moderate TBI (0.77 vs. 0.89 ng/dL, p = 0.021) and correlated positively with admission GCS (ρ = 0.34, p = 0.010). Unfavorable neurological outcome at 6 months occurred in 26/54 evaluable patients (48%). After adjusting for age, sex, admission GCS, and cranial computed tomography score, each 0.1 ng/dL decrease in baseline fT4 increased odds of unfavorable outcome by 28% (adjusted odds ratio [OR] 1.28; 95% confidence interval 1.07-1.55; p = 0.007). At 1 year, 18/50 (36%) and 15/50 (30%) screened positive for depression and anxiety, respectively. Lower early fT4 independently predicted both depressive (adjusted OR 1.35 per 0.1 ng/dL decrease; p = 0.004) and anxiety symptoms (adjusted OR 1.29; p = 0.017). Serial measurements demonstrated spontaneous T4 normalization in most survivors by 6 months.

Early reduction in serum fT4 frequently occurs after moderate-to-severe TBI and independently predicts functional recovery and subsequent affective morbidity. Routine fT4 measurement during the acute phase may enhance prognostication and identify patients requiring endocrine and psychological surveillance.

K.G. contributed to concept, data acquisition, analysis, and manuscript draft. R.K.A. contributed to supervision and critical revision. S.S. contributed to statistical analysis. All authors approved the final manuscript.

Approved by the Institutional Ethics Committee, AIIMS Rishikesh (IEC/19/NeuSurg/45).

Article published online:
29 April 2026

© 2026. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

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