Reticulocytes are slightly immature red blood cells. A reticulocyte count is a blood test that measures the amount of these cells in the blood.
How the Test is Performed
A blood sample is needed.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
How to Prepare for the Test
No special preparation is necessary.
A normal result for healthy adults who are not anemic is around 0.5% (0.005 × 10-3) to 2.5% (0.025 × 10-3).
The normal range depends on your level of hemoglobin. Hemoglobin is a protein in red blood cells that carries oxygen. The range is higher if hemoglobin is low, from bleeding or if red cells are destroyed.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Multiple punctures to locate veins
- Hematoma (blood buildup under the skin)
- Infection (a slight risk any time the skin is broken)
What Abnormal Results Mean
A higher than normal reticulocytes count may indicate:
- Anemia due to red blood cells being destroyed earlier than normal (hemolytic anemia)
- Blood disorder in a fetus or newborn (erythroblastosis fetalis)
- Kidney disease, with increased production of a hormone called erythropoietin
A lower than normal reticulocyte count may indicate:
- Bone marrow failure (for example, from a certain drug, tumor, radiation therapy, or infection)
- Cirrhosis of the liver
- Anemia caused by low iron levels, or low levels of vitamin B12 or folate
- Chronic kidney disease
Reticulocyte count may be higher during pregnancy.
Why the Test is Performed
The test is done to determine if red blood cells are being created in the bone marrow at an appropriate rate. The number of reticulocytes in the blood is a sign of how quickly they are being produced and released by the bone marrow.
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Chernecky CC, Berger BJ. Reticulocyte count – blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. Philadelphia, PA: Elsevier; 2013:980-981.