Haematology

Reticulocyte Production Index (RPI)

Marrow response corrected for anaemia and maturation.

Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.

When to use

Use in anaemia to judge whether the bone marrow response is adequate, correcting both for haematocrit and reticulocyte maturation time.

Why use

It refines the reticulocyte count into a true measure of marrow output.

Critical actions

RPI = retic% × (Hct/45) ÷ maturation factor (1 at Hct≥35, 1.5 at 25–34, 2 at 20–24, 2.5 if <20).

Evidence & references

  1. Reticulocyte production index — standard maturation-corrected calculation.

Related calculators

Corrected Reticulocyte CountReticulocyte count adjusted for anaemia.Mentzer IndexThalassaemia trait vs iron-deficiency anaemia.

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