Question

A reticulocyte count reveals 305 reticulocytes per 1000 RBCs on a 6 year old black male with sickle cell disease. The patient's RBC count is 2.95 x 106/L and the hematocrit is 27%. Calculate the following values: a. Uncorrected reticulocyte count b. Absolute reticulocyte count Corrected reticulocyte count d. Reticulocyte production index e. Are the values consistent with patient's disease state, explain.

Answer 1

a. Uncorrected reticulocyte count

Uncorrected reticulocyte count = 305 / 1000 * 100 =0.305 *100

=30.5 %

It is calculated as percentage.

b. Absolute reticulocyte count

Absolute reticulocyte count = Reticulocyte % * RBCs count / 100

=30.5 * 2950000/100

=899750

c. Corrected reticulocyte count

Corrected reticulocyte count = Reticulocytes % * actual hematocrit / normal hematocrit

= 30.5 * 27 / 45 (normal hematocrit count in male is 45)

= 30.5 * 0.6

=18.3 cells/uL

d. Reticulocyte production index

Reticulocyte production index (RPI) = Corrected reticulocyte count / Maturation time (days)

= 18.3 / 2 (maturation time for 25 -34% hematocrit is 2 days)

= 9.15

e.No. the values are not consistent with the disease state. RPI > 3%  indicates loss of red blood cells with an increased compensatory production of reticulocytes to replace the lost RbCs.