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. Reticulocytes are in the blood for about 2 days before
developing into mature red blood cells. Normally, about 1% to 2% of the red
blood cells in the blood are reticulocytes.
count rises when there is a lot of blood loss or in certain diseases in which
red blood cells are destroyed prematurely, such as
hemolytic anemia. Also, being at high altitudes may
cause reticulocyte counts to rise, to help you adjust to the lower oxygen
levels at high altitudes.
Why It Is Done
A reticulocyte count is done
- See whether
anemia is caused by fewer red blood cells being made
or by a greater loss of red blood cells.
- Check how well bone marrow is working to make red blood cells.
- Check to see if treatment
for anemia is working. For example, a higher reticulocyte count means that iron
replacement treatment or other treatment to reverse the anemia is
How To Prepare
You do not need to do anything before
you have this test.
How It Is Done
The health professional drawing blood
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure to the site and then a
How It Feels
The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
There is very little chance of a problem from
having blood sample taken from a vein.
- You may get a small bruise at the site. You can
lower the chance of bruising by keeping pressure on the site for several
- In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.
- Ongoing bleeding can be a
problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and
other blood-thinning medicines can make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your doctor before your blood sample is taken.