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Corrected Reticulocyte Count (CRC)

What is the meaning of corrected reticulocyte count?

Corrected reticulocyte count (CRC), also known as reticulocyte index (RI), is a measurement used to assess bone marrow response in diagnosing anemia. In a healthy individual, the reticulocyte index typically falls between 0.5% and 2.5%.

When a patient has anemia (hemoglobin levels below 13-14 g/dL in males and 12-13 g/dL in females), a reticulocyte index below 2% indicates reduced production of reticulocytes rather than a loss of red blood cells. Individuals with an inappropriate marrow response may require further examination for nutritional deficiencies or bone marrow abnormalities.

A CRC exceeding 3% in an anemic person suggests a loss of red blood cells (due to factors like destruction or bleeding), accompanied by increased compensatory production of reticulocytes to replenish the lost cells.

The corrected reticulocyte count Formula

The corrected reticulocyte count (CRC) can be calculated using the following equation:


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

The commonly used value for normal hematocrit (Normal Hematocrit) is 45%, but you can modify it in the advanced mode of the reticulocyte index calculator.

Maturation is a coefficient used to account for the longer lifespan of prematurely released reticulocytes in the blood, which occurs due to the increased production of red blood cells.

This coefficient is 1.0 for a hematocrit range of 36-45%, 1.5 for 26-35%, 2.0 for 16-25%, and 2.5 for a hematocrit of 15% or lower. You can find the assigned value by selecting advanced mode.

Reticulocyte index calculator

How do you use the reticulocyte index calculator?

  1. Enter the patient’s hematocrit (Hct) level as a percentage.
  2. Enter the reticulocyte level as a percentage.
  3. If desired, select advanced mode to adjust the normal hematocrit percentage.

The calculated corrected reticulocyte count will be displayed as a percentage in the final field.

Interpretation of Corrected Reticulocyte Count

The reticulocyte index it interpreted together with other hematological studies in order to determine the cause of anemia and whether the bone marrow is responding appropriately.

In general the following cut-offs are used

  • Normal Range – 0.5% and 2.5%
  • Anemic Patient  with CRC – < 2% – Decreased bone marrow function
  • Anemic Patient with CRC – >3% – Increased blood loss

Once you have finished using this calculator, you may also find our hematocrit hemoglobin ratio calculator of interest.

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