APLIKASI KLINIS RETIKULOSIT

Abstract

Reticulocytes are immature nonnucleated erythrocytes that are released from the bone marrow following enucleation of
the normoblast. Under the in! uence of erythropoietin, committed erythroid progenitor cells divide and differentiate through a
series of stages, giving rise basophilic normoblasts, polychromatophilic normoblasts, and orthochromic normoblastsin sequence.
Reticulocytes are similar to mature red blood cells, except that they retain functioning polyribosomes and continue to synthesize
hemoglobin. Because the reticulocyte stage of erythroid differentiation only lasts a few days, the number of reticulocytes in the
blood is a useful clinical indicator of the rate of erythropoiesis. Reticulocytes exist in the circulation for only 1 ? 2 days and signal
the marrow erythropoietic activity 3 ? 4 days after iron was actively incorporated into haemoglobin. Early changes in reticulocyte
count may simply re! ect the release of immature reticulocytes from the marrow rather than the true expansion of erythropoiesis.
Reticulocyte counts have once again acquired great interest and importance following the introduction of instruments that use
dyes speci" c for RNA. This has resulted in precise and accurate counts even at low reticulocyte concentrations The latest
generation of automated analyzer provides additional information on reticulocytes, such as the immature reticulocyte fraction
(IRF) and other reticulocyt indices, eg, mean reticulocyte volume (MCVr) and mean reticulocyte haemoglobin content (CHr).
To date, the most widely studied of the reticulocyte indices is the CHr. The hemoglobin content is considered to be constant
throughout the lifetime of erythrocytes and circulating reticulocytes1 unless structural changes take place that compromise the
amount of cytoplasm or cause cellular fragmentation. The normal value for the ! owcytometry method can range from 1% to
2% depending on the cut off point used to separate reticulocytes from the normal red blood cell population. Since reticulocyte
enumeration provides information about the bone marrow activity and the effectiveness of red blood cell production, it is crucial
in the clinical application of reticulocytes parameters to aid the diagnosis of anemic patients, and for monitoring bone marrow
transplantation patients, patients undergoing therapy with marrow toxic drugs, and patients being treated for anemia