Disclosed herein are assays and methods of diagnosing strokes using glycogen phosphorylase-BB (GPBB) as the biomarker. Specifically, assays and methods are described herein for distinguishing an ischemic brain condition from myocardial infarction, or distinguishing an ischemic brain condition from stroke mimics, or distinguishing an ischemic stroke from a hemorrhagic stroke. The diagnostic results offered by these assays and methods allow early and appropriate treatment for the specific condition. Also disclosed is a method to identify whether a subject having an ischemic stroke exhibits salvageable brain tissue.
