MedlinePlus Medical Encyclopedia: Reticulocyte count

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Reticulocyte count

Contents of this page:
Illustrations Definition How the test is performed How to prepare for the test How the test will feel	Why the test is performed Normal Values What abnormal results mean What the risks are Special considerations

Illustrations

Reticulocytes

Definition Return to top

This is a test that measures the percentage of reticulocytes (slightly immature red blood cells) in blood.

How the test is performed Return to top

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

For infants and small children, the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

A special stain can be used to identify reticulocytes, because they contain a substance called RNA, while fully mature red blood cells do not. The number of reticulocytes in the blood indicates how quickly they are being produced and released by the bone marrow. Normally, the body will respond to bleeding or hemolytic anemia (breakdown of red blood cells) by an increased rate of red blood cell production. A lower-than-normal percentage of reticulocytes usually indicates a nutritional deficiency.

How to prepare for the test Return to top

No special preparation is necessary for adults.

For infants and children:
The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics:

infant test or procedure preparation (birth to 1 year)
toddler test or procedure preparation (1 to 3 years)
preschooler test or procedure preparation (3 to 6 years)
schoolage test or procedure preparation (6 to 12 years)
adolescent test or procedure preparation (12 to 18 years)

How the test will feel Return to top

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed Return to top

To determine if red blood cells are being created in the bone marrow at an appropriate rate.

Normal Values Return to top

The normal range is 0.5-2%.

The normal range is higher if there has been any blood loss or red blood cell destruction.

What abnormal results mean Return to top

A higher-than-normal percentage of reticulocytes may indicate:

erythroblastosis fetalis
hemolytic anemia
post-hemorrhage (bleeding)
kidney disease with increased erythropoietin production

A lower-than-normal percentage of reticulocytes may indicate:

bone marrow failure (for example, from toxicity, tumor, fibrosis, infection)
cirrhosis of the liver
folate deficiency
iron deficiency
radiation therapy
vitamin B-12 deficiency
kidney disease with decreased erythropoietin production

Additional conditions under which the test may be performed:

What the risks are Return to top

excessive bleeding
fainting or feeling light-headed
hematoma (blood accumulating under the skin)
infection (a slight risk any time the skin is broken)
multiple punctures to locate veins

Special considerations Return to top

The reticulocyte count may be increased during pregnancy.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Update Date: 6/1/2003

Updated by: Marcia S. Brose, M.D., Ph.D., Division of Hematology/Oncology, Hospital of the University of Pennsylvania, Philadelphia, PA. Review provided by VeriMed Healthcare Network.

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