Corrected Reticulocyte Count Calculator

Created by Małgorzata Koperska, MD
Reviewed by Bogna Szyk and Steven Wooding
Based on research by
Priya P P, A R S. Role of absolute reticulocyte count in evaluation of pancytopenia-a hospital based study. Journal of Clinical and Diagnostic Research (August 2014)See 1 more source
Bessman JD. Reticulocytes. (Chapter 156) In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. (1990)
Last updated: Aug 16, 2022

The CRC – corrected reticulocyte count calculator estimates the reticulocyte index in the patient's blood, taking into account their reticulocyte and hematocrit levels. It is calculated similarly to the raw reticulocyte count, but, to avoid misinterpretation in anemic patients, the result is corrected using a coefficient of reticulocyte maturation.

In the advanced mode, there is also an option to input a desired normal hematocrit value. If you read on, you can learn the reticulocyte production index formula.

💡 Reticulocyte count is the proportion of immature red blood cells in a person's blood.

What is corrected reticulocyte count?

Corrected reticulocyte count (CRC), sometimes called reticulocyte index (RI), is a parameter for bone marrow response assessment used in the diagnosis of anemia. The reticulocyte index of a healthy person should be between 0.5% and 2.5%.

If the patient has anemia (hemoglobin of less than 13 to 14 g/dL in males and 12 to 13 g/dL in females), a reticulocyte index of less than 2% does not indicate loss of red blood cells, but decreased production of reticulocytes. Patients with an inappropriate marrow response may be further evaluated for nutritional deficiencies or bone marrow abnormalities.

A CRC of more than 3% in a person with anemia indicates loss of red blood cells (from causes such as destruction, bleeding, etc.), with increased compensatory production of reticulocytes to replace the lost red blood cells.

What's the reticulocyte production index formula?

The CRC – corrected reticulocyte count is calculated using this equation:

CRC = (Hematocrit / normal_Hematocrit) × (Reticulocytes / Maturation)

  • A value of 45% is most frequently used as normal hematocrit (normal_Hematocrit), but you can change it in the advanced mode in the reticulocyte index calculator.

  • Maturation is a coefficient used to correct for the longer lifespan of prematurely released reticulocytes in the blood, which is a phenomenon of increased red blood cell production.

    This factor equals 1.0 for a hematocrit of 36-45%, 1.5 for 26-35%, 2.0 for 25-16%, and 2.5 for a hematocrit of 15% or lower.

    You can see the assigned value by clicking advanced mode.

How to use the reticulocyte index calculator?

  1. Enter the patient's hematocrit (Hct) level in %.

  2. Enter the reticulocyte level in %.

  3. If you wish, enter advanced mode to change the normal hematocrit in %.

  4. The calculated corrected reticulocyte count is provided in % in the last field.

After you've finished with this calculator, you might also be interested in our hematocrit hemoglobin ratio calculator.

Małgorzata Koperska, MD
Hematocrit (Hct)
Corrected reticulocyte count (CRC)
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