Significance of Elecsys (R) S100 immunoassay for real-time assessment of traumatic brain damage in multiple trauma patients

Background: The neuroprotein S100 released into the circulation has
been suggested as a reliable marker for primary brain damage.
However, safe identification of relevant traumatic brain injury
(TBI) may possibly be hampered by S100 release from peripheral
tissue. The objective of this study was to measure early S100
levels using the Elecsys((R)) S100 immunoassay for real-time
assessment of severe TBI in multiple trauma. Methods: Consecutively
admitted multiple trauma patients (injury severity score >= 16
points) were stratified according to the results of the initial
cerebral computed tomography (CCT) examination. S100 serum levels
were determined at admission and at 6, 12, 24, 48 and 72 h after
trauma. Data were correlated to creatine phosphokinase (CK) and
lactate dehydrogenase (LDH) serum levels. Using receiver operating
characteristic (ROC) analysis, the discriminating power of S100
measurement was calculated for the detection of CCT+ findings.
Results: Median S100 levels of CCT+ patients (n=9; 37 years)
decreased from 3.30 mu g/L at admission to 0.41 mu g/L 72 h after
trauma. They revealed no significant differences to CCT- patients
(n=18; 44 years), but remained elevated compared to controls.
Median CK and LDH levels correlated with the corresponding S100
levels during the first 24 h after trauma. ROC analysis displayed a
maximum area under the curve of only 0.653 at 12 h after trauma. No
significant difference was calculated for the differentiation
between CCT+ and CCT- patients. Conclusions: Measurements of S100
serum levels using the Elecsys((R)) S100 immunoassay are not
reliable for the real-time detection of severe TBI in multiple
trauma patients. Due to soft tissue trauma or bone fractures, S100
is mainly released from peripheral sources such as adipocytes or
skeletal muscle cells.