A reticulocyte count is a blood test
that measures how fast
red blood cells called
reticulocytes are made by the bone marrow and released
into the blood.
The reticulocyte count is given as the
percentage of red blood cells that are reticulocytes (the number of
reticulocytes divided by the total number of red blood cells, multiplied by
The normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Results are ready in
Newborns have a normal reticulocyte count of 2.5% to 6.5%.
This value drops within 2 weeks to 0.5% to 2.0%.
- A high reticulocyte count may mean more red
blood cells are being made by the bone marrow. This can occur after a lot of
bleeding, a move to a high altitude, or certain types of anemia. These
conditions cause red blood cells to break down (hemolysis).
reticulocyte count rises after the treatment for
iron deficiency anemia, or
folic acid deficiency anemia starts working.
- A low reticulocyte count may mean fewer red
blood cells are being made by the bone marrow. This can be caused by
aplastic anemia or other types of anemia, such as iron
- A low reticulocyte count can also be caused by
exposure to radiation, a long-term (chronic) infection, or by certain medicines
that damage the bone marrow.
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
What To Think About
- In anemia, the reticulocyte count will be
abnormal because the levels of red blood cells and hemoglobin are low. Also,
reticulocytes make up a higher percentage of the blood count in anemia, which
makes the reticulocyte count falsely high. For this reason, a doctor will check
the reticulocyte count along with the reticulocyte index (RI) when checking for
anemia. The RI is a measurement for reticulocytes when anemia is
- A reticulocyte count may help a doctor choose other tests
that need to be done to diagnose a specific type of anemia or other disease. A
low reticulocyte count may mean a need for a bone marrow biopsy. This can tell
if there is a problem with how new reticulocytes are made by the bone marrow.
For more information, see the topic
Bone Marrow Aspiration and Biopsy.