The hypothesis is that a stroke causes release of purines from brain into blood and that this is a very early biomarker of brain ischaemia. The investigators propose a simple blood test of substances (the purines) that result from cellular metabolism and are produced in excess when brain cells are starved of oxygen and glucose (as occurs during a stroke).

In this study, the investigators propose to use newly developed biosensor technology (SMARTCap) to directly address whether purines are indicators of real strokes, and can distinguish strokes from other conditions with similar symptoms, more rapidly.

Inclusion Criteria:

1. Stroke patients: Admitted to the Hyperacute Stroke Unit having a suspected stroke within 1 hour of admission. Important to note that not all these patients will have suffered a stroke
2. Control participants: Relatives of patients admitted to the stroke treatment pathway, who are healthy and have no signs of cardiovascular illness
3. Healthy volunteers

Exclusion Criteria:

1. Stroke patients: Delay in admission exceeds the time window of 4 hours between stroke symptoms and admission
2. Control participants: Obvious signs or history of cerebrovascular disease
3. Unhealthy volunteers

320