Sysmex Xtra Online | March 2012 The term ‘NRBC’ - ‘nucleated red blood cells’ - refers to precursor cells of the red blood cell lineage which still contain a nucleus; they are also known as erythroblasts or - obsolete - normoblasts. In healthy adults and older children, NRBC can only be found in blood-building bone marrow where they mature. Their appearance in peripheral blood points to extramedullary erythropoiesis (outside the bone marrow) or disruption of the blood - bone marrow barrier. Both possible scenarios can only be found in the course of a severe disease. Physiologically, NRBC occur in peripheral blood only in neonates and premature babies. What does the NRBC count in neonates tell us? It is a well-known necessity to determine the number of NRBC in blood samples from neonates in order to receive an accurate result of the white blood cell (WBC) count -either by manual correction or by an automated correction on the haematology analyser. Beyond that, counting the NRBC in peripheral blood from neonates can give valuable additional information. Already in the year 1924, reference values for the number of NRBC found in neonates on their first day of life have been published [1]. 41 of the 42 neonates examined in this study showed NRBC in peripheral blood, namely with an average number of 500 NRBC/^L or 0.1 % of the circulating red blood cells, respectively. In the following decades, different authors showed similar results for neonates during their first days of life; some of these references are shown in table 1. The table also lists reference values for premature babies. In healthy neonates, the NRBC normally disappear from peripheral blood within the first week of life. Reference (first author) Sample number Time after birth Gestational age Buonocore[5] 47 8521 ± 1620 birth (cord blood) 24-27 weeks Table 1: Reference values from healthy neonates corresponding to time after birth and gestational age

Sysmex Xtra Online | March 2012 | 7 pages The clinical relevance of measuring NRBC in the XN-CBC Even in premature babies and neonates, knowing the exact number of NRBC allows drawing conclusions on their condition of health. Thus, NRBC counts greater than the indicated reference values may, for instance, refer to chronic or postnatal hypoxia, anaemia, maternal diabetes, or acute stress. Extremely increased values of up to 500 NRBC/100 WBC may even indicate an infectious disease such as congenital syphilis [6 ]. Although in 1 –2% of the cases extremely increased NRBC concentrations might be idiopathic...

Sysmex Xtra Online | March 2012 | 7 pages The clinical relevance of measuring NRBC in the XN-CBC Flow cytometric count There are different possibilities of determining NRBC with the help of antibody-mediated flow cytometry. All of these have in common that an antibody sensitive against surface characteristics of the cells (CD; ‘cluster of differentiation’) is needed. Usually, an antibody against CD71 is used, which is only expressed on red blood cells (RBC), both mature and immature. To make sure that mature non-nucleated RBC can be differentiated from immature nucleated RBC, nuclei and DNA,...

Sysmex Xtra Online | March 2012 | 7 pages The clinical relevance of measuring NRBC in the XN-CBC Side scattered light Nucleated red blood cells Very weak Very weak Granulocytes (neutrophils, eosinophils) Fig. 1: Labelling mechanism in the WNR channel With the haematology analysers of the XN-Series, NRBC can be accurately counted in both low and high measurement ranges and results are given as absolute (NRBC#) and relative values (NRBC %,/100 WBC) (fig. 3). Determining and displaying also the absolute count prevents e. g. the relative NRBC value to appear very low under the circumstances of a...

Sysmex Xtra Online | March 2012 | 7 pages The clinical relevance of measuring NRBC in the XN-CBC Fig. 3: Main screen view of a normal measurement result Studies on the clinical relevance of the NRBC count The below mentioned studies from the years 2002-2011 have all been carried out on the XE-2100 analyser. Nevertheless, the resulting conclusions can be applied to the XN-Series. ■ Study of stem cell transplanted patients, performed at Jikei University Tokyo, ■ NRBC detection rates in the peripheral blood of 44 patients with different malignant haematological diseases were compared, starting from...

Sysmex Xtra Online | March 2012 | 7 pages The clinical relevance of measuring NRBC in the XN-CBC ■ Study of thalassaemia patients, performed at two hospitals in Salerno und Palermo, Italy, published in 2009 [11]: ■ In this study, NRBC concentrations in the peripheral blood of 152 thalassaemia patients were evaluated and compared with the results of 26 patients with hereditary spherocytosis. ■ The number of NRBC reflected the ineffectiveness of the erythropoiesis: the highest numbers were found in thalassaemia syndromes with almost completely ineffective erythropoiesis whereas in patients with...

Sysmex Xtra Online | March 2012 | 7 pages The clinical relevance of measuring NRBC in the XN-CBC References [1] Lippman HS. (1924): Morphologic and quantitative study of blood corpuscles in the newborn period. Am J Dis Child 27 : 473 – 515. [2] Naye RL, Localio AR. (1995): Determining the time before birth when ischemia and hypoxemia initiated cerebral palsy. Obstet Gynecol 86 : 713 – 19. [3] Green DW. (1990): Mimoumi G. Nucleated erythrocytes in healthy infants and in infants of diabetic mothers. J Pediatr 166 : 129 –31. [4] Green DW, Hendon B, Mimouni FB. (1995): Nucleated erythrocytes and...