Abstract
S100B, a calcium-binding protein, is located primarily in astrocytes and Schwann cells. It is released into the circulation following traumatic brain injury (TBI) and a low concentration of SI00B has a good negative predictive value to not proceed to computed tomography (CT) scan. S100B measurement in patients presenting with suspected minor TBI could potentially reduce the number of CT scans performed by 30%. It may be particularly useful in alcohol-intoxicated patients where symptoms of brain injury and intoxication are similar. However, the effect of alcohol ingestion on serum S100B concentration is not established and previous studies have produced conflicting results.
The effect of increased blood alcohol concentration on serum S100B concentrations (Roche Elecsys) in two groups was investigated. Twelve healthy volunteers (group 1) were given an oral alcohol load (ethyl alcohol), followed by alcohol infusion until blood alcohol concentrations reached steady state (100 mg/dL). S100B was measured prealcohol infusion, and then hourly for five hours once steady state had been achieved. Group 2 comprised 61 non-traumatized, ethyl alcohol-intoxicated individuals (mean ethanol 251 ± 87 mg/dL) presenting to accident and emergency due to their intoxication but with no biochemical evidence of chronic alcohol abuse. S100B was measured on admission and compared against concentrations in 60 anthropometrically matched sober volunteers. An S100B concentration <0.105 μg/L was considered normal.
Alcohol infusion had no effect on S100B concentrations in group 1. However, mean serum S100B concentration in group 2 was raised (0.193 ± 0.45 μg/L) relative to the control group (0.063 ± 0.059 μg/L). Many (39%) intoxicated individuals, but no controls, had S100B concentrations >0.105 μg/L. No correlation was demonstrated between alcohol and S100B concentration.
Subjects were screened for extracranial sources of S100B before inclusion in the study; therefore, these results appear to show a genuine increase in S100B associated with alcohol consumption in some individuals. Differences between the intoxicated and infused groups could be explained by higher blood alcohol concentrations in most of the intoxicated individuals. In conclusion, alcohol concentrations above 100 mg/dL may result in an increase in S100B concentration.