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HematologyRPI

Reticulocyte Production Index Calculator

Calculate corrected reticulocyte percentage and reticulocyte production index.

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Corrected reticulocyte percentage

Reticulocyte Production Index

Reference Hct: % · Maturation factor:

About

The reticulocyte production index (RPI) first adjusts a reticulocyte percentage for the patient's hematocrit, then divides that corrected percentage by a selected maturation factor. The two outputs are distinct. Maturation factors are approximate conventions, and modern laboratories may also report absolute reticulocyte count or immature reticulocyte fraction.

Formula

Corrected reticulocyte (%) = reticulocyte (%) × patient hematocrit / reference hematocrit
RPI = corrected reticulocyte (%) / maturation factor

Interpretation

Worked example: Reticulocytes 6%, patient hematocrit 30%, reference hematocrit 45%, and factor 2 gives corrected reticulocytes 4% and RPI 2.

Reference hematocrit: Enter the reference value appropriate to the laboratory and context rather than assuming one universal normal value.

Limitations: The maturation factor is a semi-quantitative approximation. This calculator reports the arithmetic and does not label marrow response as adequate or inadequate.

References

  1. Hillman RS. Characteristics of marrow production and reticulocyte maturation in normal man in response to anemia. J Clin Invest. 1969;48:443-453.
  2. American Society of Hematology. Reflections on the Reticulocyte Count: The Importance of a Complete Blood Count. 2021.

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Disclaimer

Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.