At a Glance
Why Get Tested?
To evaluate any change in the number of red blood cells in your blood
When to Get Tested?
As part of a full blood count (FBC), which may be requested for a variety of reasons
A blood sample drawn from a vein in your arm or by a finger-prick (children and adults) or heel-prick (newborns)
The Test Sample
What is being tested?
This test counts the number of red blood cells (RBC) in a litre of blood. Red blood cells, which are made in the bone marrow, carry oxygen from the lungs to the cells and transport carbon dioxide from the cells to the lungs. Women tend to have lower RBC counts than men, and levels tend to decrease with age. Changes in RBC are usually associated with changes in haemoglobin levels. When the values of the RBC and haemoglobin decrease by more than 10% of the expected normal value, the patient is said to be anaemic. When the values increase above this range, the patient is said to be polycythaemic.
How is the sample collected for testing?
The test is performed on a blood sample taken by a needle placed in a vein in the arm or by a finger-prick (for children and adults) or heel-prick (for newborns).
Ask a Laboratory Scientist
* indicates a required field!
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.