D-Dimer Elevation as a Blood Biomarker for Detection of Structural Disorder in Mild Traumatic Brain Injury

CT scans are useful in patients with traumatic brain injury (TBI), but the potential risks associated with ionizing radiation are unknown. Further, CT scans are not commonly available in developing countries. In this study, coagulopathy and abnormal fibrinolysis were investigated as blood biomarkers for detection of structural disorder in mild traumatic brain injury (TBI). A total of 88 patients with mild and isolated TBI (Glasgow Coma Scale [GCS] score 14-15) were admitted to Kenwakai Ootemachi Hospital between October 2014 and March 2016. After exclusion of those treated with oral antiplatelet agents and anticoagulants, 73 patients were included in this study. Patients were classified into those with (lesion [+]) and without (lesion [-]) intracranial structural disorder, based on CT scans at admission and follow-up CT or MRI. Age, GCS score, and blood test findings (platelet count, international normalized ratio of prothrombin time [PT-INR], activated partial thromboplastin time [APTT], fibrinogen, fibrin/fibrinogen degradation products [FDP], and D-dimer) on admission were compared between the two groups. The lesion(+) and lesion(-) groups comprised 54 (74%) and 19 patients (26%), respectively. In multivariate logistic regression analysis, D-dimer (3.6 vs. 0.8 μg/mL) was the only significant independent risk factor for structural disorder (p < 0.001). Platelet counts (23.9 vs. 23.5 × 10⁴ /μL), PT-INR (1.05 vs. 1.07), APTT (29.3 vs. 31.7 sec), FDP (12 vs. 2.4 μg/mL), and fibrinogen levels (260.6 vs. 231.3 mg/dL) were not associated with structural disorder. These results show that D-dimer is associated with intracranial structural disorder in mild TBI.