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Serum S-100B Protein in Severe Head Injury

2000; Lippincott Williams & Wilkins; Volume: 46; Issue: 4 Linguagem: Inglês

10.1227/00006123-200004000-00063

1524-4040

Chris Woertgen, Ralf Dirk Rothoerl,

Neonatal Respiratory Health Research

To the Editor: Raabe et al. (2) have collected a large amount of data in this prospective study of patients sustaining severe head injury. However, we have some concerns about this study, which we would like to explain. The biological half-life of the protein S-100B in serum is 2 hours, as mentioned by Raabe et al. The first serum sample in this study was obtained between 2 hours and 40 hours after trauma. According to Ingebrigtsen et al. (1) and our own experience with this serum marker (6), a rapid posttraumatic release of the protein into the serum and, according to the half-life, a rapid decline in the first hours after trauma have to be expected (3–5). Therefore, the collected data of Raabe et al. are questionable regarding the correlation between the first serum level of S-100B and the primary brain damage after head injury. Another flaw of this study is that S-100B was measured with two different assays. The radioimmunoassay kit used in this study had a detection limit of 0.2 μg/L, and the immunoluminometric assay kit used had a detection limit of 0.02 μg/L. To obtain comparable results, especially in the lower concentrations of S-100B, it does not seem advisable to use two different kits with a 10-fold difference in detection limit, especially when the definition of normal values is defined as low as 0.13 μg/L (p 478, Patients and Methods). To calculate the specificity and sensitivity of S-100B serum levels concerning outcome, Raabe et al. used the peak values of serum levels obtained during the first 10 days of treatment. According to the kinetics of S-100B after severe head injury, it does not seem advisable to use peak values at any time point during treatment (with gaps of 24 hours) to calculate the sensitivity with regard to outcome. What is the benefit for the neurosurgeon and/or patient in knowing that a serum level is elevated during the first 10 days when there are other online parameters (e.g., intracranial pressure, Licox)? The S-100B estimation takes at least 3 to 4 hours, and there is no single probe kit. Contrary to Raabe et al., we think that S-100B serum levels collected between 2 and 6 hours after trauma are more able to reflect primary brain damage with a better specificity (82%) and sensitivity (75%), regarding the correlation with long-term outcome (6). Thus, the S-100B serum level could be used as an objective indicator of the severity of brain damage during the first few hours after trauma to determine whether to initiate an invasive treatment. Chris Woertgen Ralf Dirk Rothoerl