Criteria for a clinically informative serum biomarker in acute ischaemic stroke: a review of S100B.

BACKGROUND AND PURPOSE Serum S100B has been widely studied as a biomarker in acute ischaemic stroke. The main objective of this review was to appraise the published literature on S100B and determine its clinical applicability. METHODS Medline was searched to identify studies on S100B (or S-100B) in acute ischaemic stroke. The authors have proposed the criteria for a clinically informative serum biomarker for acute ischaemic stroke, and relevant articles relating to these criteria were then selected. RESULTS Studies have shown that S100B has a low specificity for acute ischaemic stroke because of its tendency to be raised from extracranial sources. Data regarding S100B kinetics compiled from 6 longitudinal studies show that serum levels are not raised immediately following acute ischaemic stroke and peak 3 days after symptom onset. However, serum S100B levels correlate well with infarct volume and are higher in stroke patients at risk of malignant infarction or haemorrhagic transformation after thrombolysis. In addition, serum S100B levels correlate well with functional outcome. CONCLUSION The evidence suggests that S100B is not a valuable biomarker for diagnosing acute ischaemic stroke. Instead, it may have a more promising role in non-specialist hospitals, as an additional tool for identifying patients at increased risk of specific early neurological complications after stroke and as a surrogate marker of cerebral damage and functional outcome, particularly in a research setting.