Early elevation of S-100B protein in blood after cardiac surgery is not a predictor of ischemic cerebral injury.

Background: We hypothesized that early changes in S-100B levels after cardiac surgery are nonspecific and mostly reflect damage to tissues outside the brain rather than ischemic brain damage.

Methods: We measured serum levels of S-100B at several times perioperatively in 21 patients undergoing cardiac surgery. In addition, we measured levels of neuron specific enolase (NSE), glial fibrillary acidic protein (GFAP), creatine kinase (CK), the cardiac isoenzyme of CK (CK-MB), and myoglobin (MB) in these patients.

Results: Early increases in serum S-100B concentration were significantly (p<0.01) correlated with increases in markers of tissue injury outside the brain: S-100B/CK: r(2)=0.69; S-100B/CK-MB: r(2)=0.64; S-100B/myoglobin: r(2)=0.60; S-100B/NSE: r(2)=0.51; CK/NSE: r(2)=0.60; CK-MB/NSE: r(2)=0.59; and myoglobin/NSE: r(2)=0.54.

Conclusions: Our findings indicate that increases in S-100B in the early phase after cardiac surgery are not due to release of S-100B from brain alone but also from tissue outside the brain.