🩸 Reticulocyte Production Index (RPI)
Assess marrow response to anaemia with the reticulocyte production index (RPI).
Reticulocyte Production Index (RPI)
Reticulocyte (%)
Haematocrit (%)
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.