Reticulocyte Count
Overview
Reticulocyte count measures the number of immature red blood cells (reticulocytes) in peripheral blood, expressed as a percentage or absolute count, reflecting bone marrow erythropoietic activity. Reticulocytes are young erythrocytes that mature over 1-2 days, serving as an indicator of recent red cell production in response to anemia or hemolysis. Elevated counts indicate adequate bone marrow response to anemia, blood loss, or hemolysis, while low counts suggest bone marrow failure or ineffective erythropoiesis; it is clinically useful for distinguishing hypoproliferative from hemolytic anemias and monitoring bone marrow recovery.Clinical Use Cases
- Differentiating hemolytic anemia from bone marrow failure.
- Evaluating response to anemia treatment (iron, B12, folate).
- Monitoring recovery after chemotherapy or bone marrow transplant.
- Assessing blood loss or hemolysis severity.
- Diagnosing transient erythroblastopenia of childhood.
Specimen Types
- Whole blood (EDTA tube).
- Capillary blood (point-of-care).
Measurement Methods
- Automated hematology analyzers with fluorescence flow cytometry.
- Manual supravital staining with brilliant cresyl blue.
- RNA-content based immature reticulocyte fraction (IRF).
Test Preparation and Influencing Factors
- No fasting required.
- Collect promptly after blood loss or treatment initiation.
- Recent transfusion suppresses reticulocyte response.
- Correct for anemia: Reticulocyte Index = %retic × (patient Hct/45).
- Time collection: peaks 5-7 days post-hemorrhage.
Synonyms
- Retics.
- Reticulocyte percentage.
- Absolute reticulocyte count (ARC).