A methods, kits and compositions for diagnosing a central nervous system disorder, particularly transient ischemic attack or stroke, comprising measuring the level of NR2A and/or NR2B NMDA receptor or fragment thereof, in a biological sample from a human subject, and optionally measuring other biomarkers such as homocysteine and glutamate. The method is particularly useful for identifying individuals that are at risk for stroke, and for diagnosing stroke in an emergency room setting.