Reticulocyte Production Index

RPI = (Hct / 45) * Retic / Maturation


Decimal Precision  
  • The Maturation term represents the maturation time of RBC's (in days) at various levels of anemia.
  • Maturation = 1.0 for Hct ≥40%.
  • Maturation = 1.5 for Hct 30-39.9%.
  • Maturation = 2.0 for Hct 20-29.9%.
  • Maturation = 2.5 for Hct <20%.
  • An RPI >3 shows a normal marrow response to anemia. An RPI <2 is an inadequate response to anemia.
  • With a normal H&H, an RPI of 1 is normal.

  1. Hutchinson RE, Davey FR. Hematopoiesis. In: Henry JB, ed. Clinical Diagnosis and Management by Laboratory Methods 19th edition. WB Saunders 1996. NLMN ID: 9513812 NCBI Logo


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