All content on Lab Tests Online has been reviewed and approved by our Editorial Review Board.
At a Glance
Why Get Tested?
To evaluate the number of red blood cells (RBCs); used to screen for, help diagnose, or monitor conditions affecting red blood cells
When to Get Tested?
As part of a complete blood count (CBC), during a health examination, or when a health practitioner suspects that you have a condition such as anemia (decreased number of RBCs) or polycythemia (increased number of RBCs)
A blood sample drawn from a vein in your arm or by a fingerstick (children and adults) or heelstick (newborns)
Test Preparation Needed?