The correction of the reticulocyte count for the degree of anemia is called the "hematocrit correction" or the "reticulocyte index (RI)". This consists of multiplying the observed reticulocyte count by the ratio of the patient's hematocrit to the "normal" hematocrit of 45%.


Calculate the RI (corrected reticulocyte count for degree of anemia)


reticulocyte index = corrected reticulocyte count for anemia =

= (observed reticulocyte count, as a percent) * (patient's hematocrit) / 45 / 1%



• The patient's hematocrit is taken as a whole number.

• The denominator 45 represents the normal hematocrit.

• The denominator 1% indicates the normal reticulocyte count; division by 1% also allows the reticulocyte count to appear as a whole number.



• Manual reticulocyte counts have a relatively high counting error. This can be reduced by the use of counting reticulars in the ocular lens of the microscope.



• Is the equation appropriate for use in situations where hematocrits are > 45%, as is seen in newborns?


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