Outcome of patients suffering from traumatic brain injury (TBI) depends on the development of secondary brain damage. In this context, recent studies underlined the role of the natriuretic peptides- atrial natriuretic peptide and brain natriuretic peptide (BNP)-in aneurysmatic subarachnoidal hemorrhage (SAH). Especially BNP correlates with intracranial pressure and clinical outcome after SAH. Since its role in TBI remains unclear, the intracranial and systemic concentrations of N-terminal (NT)-proBNP were analyzed in patients suffering from severe TBI. We measured NT-proBNP levels in cerebrospinal fluid (CSF) and serum of 14 patients suffering from severe TBI (GCS<or=8 points) and 10 healthy control patients, using proBNP assay (Roche Diagnostics). Samples were collected after placement of a ventricular catheter, and at 12, 24, 48, and 72 h after TBI. CSF/serum albumin ratio (Q<a) was daily calculated. At 90 days after TBI, outcome was evaluated using the Glasgow Outcome Scale (GOS). In patients exhibiting a mean ICP of >15 mm Hg (n=6), the serum (800+/-150 pg/mL) and CSF levels (55+/-9 pg/mL) of NT-proBNP were significantly increased after 24 h, as compared to patients with ICP<or=15 mm of Hg (n=8) as well as to control group. However, Qa as well as GOS did not significantly differ among both groups. For the first time, we evaluated intrathecal and systemic NT-proBNP concentrations in patients suffering from severe TBI. Interestingly, NT-proBNP in CSF and serum was significantly elevated in patients exhibiting an ICP of >15 mm Hg. Further studies are currently performed to elucidate the physiologic role of NT-proBNP in TBI.