Reticulocyte count

Definition

Reticulocytes are slightly immature red blood cells. A reticulocyte count is a blood test that measures the amount of these cells in the blood.

Alternative Names

Anemia - reticulocyte

How the Test Is Performed

A blood sample is needed.

How to Prepare for the Test

No special preparation is necessary.

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.

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.

Normal Results

A normal result for healthy adults who are not anemic is around 0.5% to 2.5%.

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.

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)
• Bleeding
• 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.

Risks

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)

References

Bope ET, Kellerman RD. Hematology. In: Bope ET, Kellerman RD, eds. Conn's Current Therapy 2016. Philadelphia, PA: Elsevier; 2016:chap 12.

Bunn HF. Approach to the anemias. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 158.

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.