What are reticulocytes?
Reticulocytes are immature red blood cells (so-called erythrocytes). They no longer have a cell nucleus, but they are still able to carry out metabolic processes, as some cell organelles are still functional. One of these cell organelles is the endoplasmic reticulum.
In addition, the genetic information (RNA) is stored in the reticulocytes. Reticulocytes are formed in the bone marrow and enter the bloodstream. Maturation in the blood takes place within one day – during this process, the RNA and the endoplasmic reticulum are released. After this maturation process, the reticulocyte has now become an erythrocyte. In diagnostics, the number of reticulocytes is of relevance, as it allows the bone marrow activity to be assessed.
The reticulocyte values
The reticulocyte values are given in relation to the erythrocytes (red blood cells): That is the number of reticulocytes per 1000 erythrocytes (‰). The reference range is about 30. 000 – 80. 000 ul/blood. However, the reference range may vary slightly depending on the laboratory and should be taken into account in the evaluation.
The Reticulocyte Production Index
The reticulocyte production index is a more accurate value for assessing the maturation process of erythrocytes. In medical terminology this maturation process is called erythropoiesis. It is calculated as follows: (Reticulocyte count in percent x actual hematocrit : shift in days x normal hematocrit of 45) Two specific factors are taken into account for the calculation – once the hematocrit and once the reticulocyte shift.
The hematocrit describes the proportion of cellular components of the blood. The normal range is 33% – 43% for women and 39% – 49% for men. However, to determine the index, the hematocrit is set at a value of 45%.
This makes it easier to compare the values. The reticulocyte shift, on the other hand, prescribes a shift – there are more reticulocytes in the blood than in the bone marrow. The shift is still set in relation to the hematocrit.
In healthy people, the reticulocyte production index is one. If anemia is present, it can be seen whether it is caused by disturbed erythropoiesis. In this case the value is less than 2.
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