Reticulocyte (Retic.)Count | laboratory experiment

Reticulocyte (Retic.)Count | laboratory experiment

Reticulocyte is immature RBCs. typically composing about 1% of the red cells in the human body. Reticulocytes develop and mature in the red bone marrow and then circulate for about a day in the blood stream before developing into mature red blood cells. Like mature red blood cells, reticulocytes do not have a cell nucleus. They are called reticulocytes because of a reticular (mesh-like) network of rRNA that becomes visible under a microscope with certain stains such as methylene blue.

Reticulocyte (Retic.)Count | laboratory experiment

The reticulocyte count is blood test performed to assess the percentage of circulating red blood cells that are in the reticulocyte stage. A reticulocyte count is usually performed when patients are evaluated for anemia and response to its treatment. It is sometimes called a retic count.

The normal range of values for reticulocytes in the blood depends on the clinical situation and the lab, but broadly speaking is 0.5% to 1.5%. However, if a person has anaemia, their reticulocyte percentage should be higher than “normal” if the bone marrow’s ability to produce new blood cells remains intact.


A reticulocyte count provides information about the rate at which the bone marrow is producing red cells. A normal count means that the production is adequate; a decreased count means it is not. This information helps determine whether a lack of red cells in an anemic person is caused by a bone marrow problem, by excessive bleeding, or by red cell destruction.

The test is also used to monitor the response of bone marrow to treatment for anemia. The reticulocyte count rises within days if the treatment is successful. It is also used following bone marrow transplant to evaluate the new marrow’s cell production.

Ribosomes react with NEW METHYLENE BLUE to form a blue precipitate of granules or filaments. The reaction takes place only in vitally stained unfixed preparations. Cells containing the blue precipitate or filaments are expressed as a percentage of the red cells counted.

Equipments and reagents

12 x 75 mm disposable tube | Glass slides | Disposable pipettes | Microscope | New Methylene Blue SPECIMEN: Whole blood collected in EDTA tube.

1. Mix equal volume of whole blood and New Methylene Blue in a glass or plastic tubes.

2. Incubate the mixture at 37° C for 20 minutes.

3. Resuspend the cells by gentle mixing.

4. Make a blood film of the mixture.

5. Examine the film under oil immersion.

6. Count one thousand RBCs while tallying the number of reticulocytes.
Reticulocytes appear as cells containing dark blue granules or a blue network. The number of reticulocytes is reported as a percentage of the total red cells.

In a healthy patient, the reticulocyte percentage is very stable. When the number of RBCs decreases (thus the hematocrit decreases), the percentage of reticulocytes may appear increased compared to the overall number of RBCs.

In order to get a more accurate assessment of bone marrow function, the calculated reticulocyte percentage (%) is often corrected with a calculation called a corrected reticulocyte count or a reticulocyte index (RI). This calculation compares the patient’s hematocrit with a normal hematocrit value.

Reticulocyte (%) = [Number of Reticulocytes / Number of Red Blood Cells] X 100
Reticulocyte Index = Reticulocyte count (%) X [Measured hematocrit / Normal hematocrit]

Normal results
Adults have reticulocyte counts of 0.5-2.5%. Women and children usually have higher reticulocyte counts than men.

Abnormal results

A low reticulocyte count indicates that the bone marrow is not producing a normal number of red blood cells. Low production may be caused by a lack of vitamin BR12R, folic acid, or iron in the diet; or by an illness affecting the bone marrow (for example, cancer). Further tests are needed to diagnose the specific cause.

The reticulocyte count rises when the bone marrow makes more red cells in response to blood loss or treatment of anemia.


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