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Reticulocyte Production Index (RPI)
Hematology / Anemia Workup
The RPI corrects the reticulocyte count for the degree of anemia and for premature release of reticulocytes into the circulation (shift reticulocytes). An RPI <2 suggests inadequate bone marrow response (hypoproliferative anemia); RPI >3 indicates active erythropoiesis (hemolysis or blood loss).
Maturation Factor Reference
| Hematocrit | Maturation Factor |
|---|---|
| ≥45% | 1.0 |
| 35–44% | 1.5 |
| 25–34% | 2.0 |
| <25% | 2.5 |
Formula
Corrected Retic = Retic% × (Patient Hct / 45)
RPI = Corrected Retic / Maturation Factor
RPI = Corrected Retic / Maturation Factor
Clinical Notes
RPI <2 (Hypoproliferative): Consider iron deficiency anemia, vitamin B12/folate deficiency, aplastic anemia, anemia of CKD, anemia of chronic disease, hypothyroidism, bone marrow infiltration.
RPI >3 (Hyperproliferative): Consider hemolytic anemia (autoimmune, microangiopathic, G6PD deficiency, hereditary spherocytosis), acute blood loss, recovery from nutritional deficiency.
RPI >3 (Hyperproliferative): Consider hemolytic anemia (autoimmune, microangiopathic, G6PD deficiency, hereditary spherocytosis), acute blood loss, recovery from nutritional deficiency.
For educational use only. Clinical decisions must incorporate full patient evaluation.
