BNP and NT-proBNP Concentrations in Paired cerebrospinal Fluid and Plasma Samples of Patients with Traumatic Brain Injury

Background: The aim of this study was to investigate the secretion pattems of brain natriuretic peptide (BNP) and N-terminal-proBNP (NT-proBNP) after traumatic brain injury (TBI) and to analyze the source of them in cerebrospinal fluid (CSF). Materials and methods: We synchronously measured BNP and NT-proBNP concentrations in paired CSF and plasma samples from 22 moderate to severe TBI patients and 40 healthy control patients. The CSF and/or plasma ratio of albumin (Q(Albumin)) was calculated daily. The BNP and NT-proBNP levels of CSF and plasma were compared between TBI patients and control patients. Results: CSF BNP and NT-proBNP levels peaked on day 3 after injury, as did the plasma BNP and NT-proBNP levels. The CSF BNP and NT-proBNP levels in TBI patients were elevated from day 1, which was significantly higher than control group (P < 0.05 and P < 0.01, respectively). However, in plasma, only NT-proBNP levels were significantly higher than in the control group from day 2 (P < 0.05). In addition, Q(BNP), defined as CSF BNP concentration and/or plasma BNP concentration, was significantly higher in TBI patients than in the control group (P < 0.01). However, Q(Albumin) remained within ranges of a mild to moderate dysfunction of blood-brain-barrier in TBI patients. Conclusions: CSF BNP concentrations are elevated and peak on day 3 after moderate to severe TBI. CSF BNP may originate from the brain and may be a potential biomarker of TBI. (C) 2021 Elsevier Inc. All rights reserved.