What this calculator does
Reticulocyte production index (RPI) works out corrects a reticulocyte percentage for anaemia severity and cell maturation time. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaCorrected retic% = retic% × (patient Hct / 45); RPI = corrected retic% / maturation factor (1.0 at Hct 36-45%, 1.5 at 26-35%, 2.0 at 16-25%, 2.5 at ≤15%)
The inputs explained
| Field | What to enter |
|---|---|
| Reticulocyte count (%) | A number, measured in %. Starts at 1.5. |
| Haematocrit (%) | A number, measured in %. Starts at 30. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with reticulocyte count
Every other input is held at the calculator’s starting values while reticulocyte count varies. Select any row to load that scenario into the calculator.