gms | German Medical Science

Objective: The neurotrophic glial protein S100B has been promoted as a marker of brain injury for more than a decade. However, evidence suggests that extracranial sources may contribute to S100B serum levels. Furthermore, no data exist about the renal elimination of S100B. In the present study we aim investigate the S100B release into serum and urine in a larger cohort.

Method: In 154 subsequent patients treated on the operative intensive care unit, we measured S100B and creatinine in serum and urine. Blood samples were taken daily, immediately centrifuged for 10 min at 1.300 xG and 4° C and stored at a temperature of –80°C until the assays were performed. Analysis was performed with commercially available kits on automated immunoanalyzers (LIAISON^® Sangtec^®100 by chemiluminescence immunoassay, Diasorin). The Sensitivity of the assay was 0.02 ng/ml. Statistical analysis was performed with SPSS, and p<0.05 was accepted as significant.

Results: The mean age of the patients was 66.1 (17 to 95) years, 74 were male and 80 female. Patients were included from the Depts. of General Surgery (n=46), Gynecology (n=7), Urology (n=5), Orthopedic Surgery (22), Vascular Surgery (n=26), Neurosurgery (n=42), and Internal Medicine (n=6). S100B in serum was increased following surgery without intracranial injury (0.44±0.07 ng/ml) as well as following neurosurgery (0.26±0.07 ng/ml). Furthermore, S100B in urine was above the detection limit following surgery without intracranial injury (0.08±0.04 ng/ml) as well as following neurosurgery (0.03±0.01 ng/ml). The renal function as estimated by the creatinine clearance did not affect the S100B secretion into urine.

Conclusions: The 10.5 KD monomeric protein S100B is not completely reabsorbed in the kidneys following an increased release into serum and urine mearsurements may thus offer an alternative source to screen for elevated S100B levels. Major surgery even without concomitant brain injury does affect S100B serum levels significantly.