M. Morsed Zaman Miah
Automated reticulocyte counts are widely used in the clinical laboratory due to their greater precision, accuracy and reproducibility compared to those obtained using the microscope. Automated methods employ a wide variety of reagents for reticulocyte RNA and these show different sensitivity on binding to RNA. Automated reticulocyte counts not only provide enhanced precision and accuracy, but also perform reliable measurements of mRNA content and of cellular indices such as volume, haemoglobin concentration and content. These novel parameters have prompted interest and studies regarding their clinical usefulness, the utility of reporting and their interpretation. Immature reticulocyte fraction (IRF) assesses reticulocyte maturation by the intensity of the staining of reticulocytes, which reflects mRNA content. IRF seems to be useful for the evaluation of engraftment in bone marrow or stem cell transplantation and bone marrow regeneration following chemotherapy. The clinical utility of IRF has been reported in a variety of conditions such as in the monitoring of anaemia treatment, neonatal transfusion needs, prognosis in prematurity, in AIDS anaemia, renal transplant engraftment due to erythropoietin production, the detection of occult or compensated haemorrhages or haemolysis, aplastic crisis in haemolytic anaemias and to verify aplastic anaemia. IFR help to differentiate aplastic anaemia from megaloblastic anaemia which are the most common cause of pancytopenia. Reticulocyte haemoglobin content is a reliable and early indicator of bone marrow iron status and may detect functional iron deficiency with more sensitivity than bio-chemical parameters. Iron-sequestration syndromes occur in chronic diseases when iron is not available for erythropoiesis, due to inappropriately high serum hepcidin values, which determine iron sequestration in reticuloendothelial system macrophages. One of the major determinants of the anaemia of chronic disease is iron sequestration. Serum hepcidin was shown not to be clinically useful or superior to more standard iron status tests, for managing iron therapy in HD patients on ESA treatment; reticulocyte haemoglobin content and percentage of hypochromic red blood cells were shown to be more useful, either alone or in combination with the transferrin saturation ratio and ferritin levels. The clinical utility of reticulocyte haemoglobin content has been well established as a reliable marker of functional iron deficiency in haemodialysis patients, exhibiting high specificity and sensitivity in the management of IV iron therapy. If the absolute reticulocyte count and IRF are simultaneously increased, an interpretative comment could be added to emphasize the increase of erythropoietic activity. This comment could help physicians assess cases of suspected haemolytic anaemia or in monitoring the treatment of anaemia.
Correspondence: M. Morsed Zaman Miah, Assistant Professor of Haematology, Rajshahi Medical College & Hospital, Rajshahi, Bangladesh. Email: [email protected].