Interpretation
| Result | Meaning |
|---|---|
| < 2 | Hypoproliferative (production defect) |
| ≥ 2 | Appropriate marrow response (hemolysis, blood loss) |
Formula
Corrected retic (%) = retic % × Hct ÷ 45. RPI = corrected retic ÷ maturation time; maturation time = 1.0 d (Hct >35%), 1.5 d (26–35%), 2.0 d (16–25%), 2.5 d (≤15%).
Clinical pearls
- Maturation-time cut-offs come from Hillman's data (Hct 45/35/25/15% ≈ 1.0/1.5/2.0/2.5 days); calculators differ slightly at band edges.
- Some references use a normal Hct of 40% for women; this calculator uses 45% for everyone.
- If the lab reports an absolute reticulocyte count, >100 ×10⁹/L generally indicates an adequate response.
Examples
reticulocyte index retic 6% hct 25rpi for retic 2 percent and hematocrit 40what is the corrected reticulocyte count with retic 10% and crit 30
FAQ
What is a normal reticulocyte production index?
About 1 in a non-anemic person. In anemia, an RPI under 2 indicates the marrow is not responding adequately; above 2 to 3 indicates an appropriate response.
Why correct the reticulocyte count?
In anemia the percentage is inflated by fewer red cells and by stress reticulocytes that circulate longer, so both corrections are needed to judge marrow output.