Reticulocyte Index
Corrects the reticulocyte count for anemia and estimates marrow response.
When to use
Adults with anemia, to estimate whether the marrow is responding adequately.
Pearls and pitfalls
- The index corrects the reticulocyte percentage for the patient hematocrit.
- The maturation factor increases as hematocrit falls.
- An index below 2 suggests an inadequate marrow response.
- The index does not replace assessment of hemolysis, bleeding and nutritional deficiencies.
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Formula
Index = reticulocytes (%) × (hematocrit ÷ 45) ÷ maturation factor, with factor 1, 1.5, 2 or 2.5 according to hematocrit.
Evidence
Index derived to correct the reticulocyte count for anemia and estimate the erythropoietic response.
References
- Hillman RS, Finch CA. Erythropoiesis: normal and abnormal. Semin Hematol. 1967;4(4):327-336. https://pubmed.ncbi.nlm.nih.gov/4865988/
Frequently asked questions
What is Reticulocyte Index?
Corrects the reticulocyte count for anemia and estimates marrow response. Adults with anemia, to estimate whether the marrow is responding adequately.
How is the result calculated?
Index = reticulocytes (%) × (hematocrit ÷ 45) ÷ maturation factor, with factor 1, 1.5, 2 or 2.5 according to hematocrit.
How should the result be interpreted?
Index derived to correct the reticulocyte count for anemia and estimate the erythropoietic response.
What are the sources?
Hillman RS, Finch CA. Erythropoiesis: normal and abnormal. Semin Hematol. 1967;4(4):327-336.