🩸 Reticulocyte Production Index (RPI)
Assess marrow response to anaemia with the reticulocyte production index (RPI).
Clinical takeaway
RPI ≥ 2–3 indicates an adequate marrow response.
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When to use
Distinguish hypoproliferative from hyperproliferative anaemia.
How it works
RPI = (reticulocyte% × Hct/45) / maturation factor (1–2.5 by Hct).
Key points
- RPI ≥ 2–3 indicates an adequate marrow response.
- RPI < 2 suggests hypoproliferative anaemia.
- Corrects for anaemia severity and maturation.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Reticulocyte | 3 % |
|---|---|
| Haematocrit | 30 % |
→RPI1.3
- Corrected reticulocyte：2.0%
- Maturation factor：1.5
- Interpretation：< 2 — inadequate response (hypoproliferative anaemia).
Frequently asked questions
- What is Reticulocyte Production Index (RPI)?
- Assess marrow response to anaemia with the reticulocyte production index (RPI).
- How is Reticulocyte Production Index (RPI) calculated? What is the core formula?
- RPI = (reticulocyte% × Hct/45) / maturation factor (1–2.5 by Hct).
- When is Reticulocyte Production Index (RPI) used?
- Distinguish hypoproliferative from hyperproliferative anaemia.
- What are the key clinical points for Reticulocyte Production Index (RPI)?
- RPI ≥ 2–3 indicates an adequate marrow response. RPI < 2 suggests hypoproliferative anaemia. Corrects for anaemia severity and maturation.
- What are the limits and cautions when using Reticulocyte Production Index (RPI)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Reticulocyte Production Index (RPI) calculated in practice? Can you show a worked example?
- Inputs: Reticulocyte 3 %, Haematocrit 30 % → Result: RPI 1.3（Corrected reticulocyte: 2.0%, Maturation factor: 1.5, Interpretation: < 2 — inadequate response (hypoproliferative anaemia).）