Reticulocyte Count
Test OverviewA 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. The reticulocyte
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 DoneA reticulocyte count is done
to: - 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
working.
How To PrepareYou do not need to do anything before
you have this test. How It Is DoneThe health professional drawing blood
will: - 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
alcohol.
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
blood.
- Remove the band from your arm when enough blood is
collected.
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure on the site and then put on a
bandage.
How It FeelsThe 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
pinch. RisksThere is very little chance of a problem from
having a 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
minutes.
- 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.
ResultsA 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. NormalThe 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
100). 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
1 day. Reticulocyte countfootnote 1| Adults: | 0.5%-1.5% |
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| Newborns: | 3%-6% |
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High valuesLow values- 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
deficiency anemia.
- 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 TestReasons you may not be able to
have the test or why the results may not be helpful include: - Taking certain medicines. Medicines that affect the results include ones used for Parkinson's disease, rheumatoid arthritis, fevers, malaria, and cancer chemotherapy.
- Getting radiation therapy.
- Taking sulfonamide antibiotics (such as
Septra).
- Being pregnant.
- Having a recent
blood transfusion.
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
present.
- 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.
To learn more, see the topic
Bone Marrow Aspiration and Biopsy.
ReferencesCitations- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Other Works Consulted- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
CreditsByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Adam Husney, MD - Family Medicine
Specialist Medical ReviewerMartin J. Gabica, MD - Family Medicine Current as ofOctober 13, 2016 Current as of:
October 13, 2016 Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins. Last modified on: 8 September 2017
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