Why get tested?
If you have anaemia (too few red blood cells) or polycythaemia (too many red blood cells), to assess its severity, and to monitor response to treatment

When to get tested?
As part of a full blood count (FBC), which may be requested for a variety of reasons

Sample required?
A blood sample drawn from a vein in your arm or by a finger-prick (children and adults) or heel-prick (newborns)