High serum protein S100B levels in brain-dead patients

S100B is a protein synthesized in astroglial and Schwann cells in the central nervous system (CNS). Only very low concentrations of this protein are normally present in serum, whereas high levels of S100B have been found in the blood of patients suffering from a variety of CNS disorders, including tumors, cerebrovascular insults or traumatic brain injury (BI). Data on S100B in patients with brain-death are sparse. To clarify this issue, 48 brain-dead (BD) patients (34 men, 14 women) with a mean (± SD) age of 48 ± 21 years (range 14–85 years) were studied. Brain-death was due to trauma (n = 35), spontaneous intracerebral hemorrhage (n = 11), intracerebral thrombosis (n = 1) and intracerebral aneurysm (n = 1). For comparison, 36 patients (32 men, 4 women), with severe traumatic BI who did not develop brain-death, having a mean age of 33 ± 15 years (range 17–70 years) were also studied. All patients were intubated and mechanically ventilated. In BD patients, blood samples for S100B determination were obtained after clinical diagnosis of brain-death. In BI patients, blood samples were collected upon admission in the hospital and every 24 hours thereafter, for a maximum of seven consecutive days; in these patients peak and average values of S100B were used for analysis. Protein S100B levels in BD patients (median 7.68 μg/l, interquartile range 4.06–14.10 μg/l) were significantly higher compared to the peak (median 1.30 μg/l, interquartile range 0.60–1.90 μg/l, P < 0.001, Mann–Whitney U test) or to the average (median 0.60 μg/l, interquartile range 0.36–0.97 μg/l, P < 0.001, Mann–Whitney U test) values of S100B in BI patients. In conclusion, serum concentrations of protein S100B are high in brain-death victims. Further prospective studies are required to determine the predictive value of S100B levels in the early diagnosis of brain-death.