A reticulocyte count is a blood test that measures the percentage of reticulocytes in the blood. Reticulocytes are slightly immature red blood cells.
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.
A normal result for healthy adults who are not anemic is around 0.5%-1.5%.
The normal range depends on the level of hemoglobin. The range is higher if there is low hemoglobin due to bleeding or red cell destruction. Hemoglobin is a protein in red cells that carries oxygen.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor 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)
Blood disorder in a fetus or newborn known as 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 drug toxicity, tumor, radiation therapy, or infection)
Reticulocyte count may be increased during pregnancy.
There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient 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:
Fainting or feeling light headed
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)
Mathur SC, Schexneider KI, Hutchison RE. Hematopoiesis. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 31.
Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.