Corrected Reticulocyte Count calculator
Result
1.6% (corrected)
RPI < 1 — Hypoproliferative anaemia (iron deficiency, aplasia, B12/folate)
Reticulocyte Production Index: 0.8 (CRC ÷ maturation factor 2).
How to use it
- 1
CRC = Retic% × (patient Hct / 45). Adjusts for the dilutional effect of anaemia on % reticulocytes.
- 2
RPI = CRC / maturation factor. Maturation factor is 2 for Hct 25–35% (days reticulocytes spend in blood).
- 3
RPI < 2. Bone marrow is not responding appropriately to anaemia.
When to use it
- Anaemia classification
- Differentiates haemolysis/blood loss (RPI ≥2) from hypoproliferative causes (RPI <2).
- Treatment response
- Iron, B12, or EPO therapy: RPI rising = early sign of marrow response.
- Sickle cell / haemolytic anaemia
- RPI > 3 confirms ongoing haemolysis despite apparent stability.
A reference for clinicians and students, not medical advice. A score supports a decision; it does not make one. Check every result against the patient in front of you and your local protocol.
At a glance
- Specialty
- Haematology
- Inputs
- 2
- Type
- Formula
