Automated nRBC Measurement Using the Sysmex XE-5000 Hematology Analyzer: Frequency and Clinical Significance of the nRBC Count
David H Hwang, David M Dorfman, Dick G Hwang, Patricia A Senna, Olga Pozdnyakova. Brigham and Women's Hospital, Boston, MA; Virginia Mason Medical Center, Seattle, WA
Background: The importance of counting nucleated red blood cells (nRBC) in peripheral blood (PB) is two-fold. First, the correct white blood cell count (WBC) and leukocyte differential count depend on recognizing nRBC and, second, it is important clinically since its presence in PB is usually associated with pathologic conditions. Until recently, the only reliable method for nRBC enumeration in PB was the manual count of peripheral smears with a low detection limit of 1 nRBC per 100 WBC. Automated nRBC enumeration by hematology analyzers has been limited by low sensitivity and specificity especially when dealing with low numbers.
Design: Validation of automated nRBC enumeration by the Sysmex XE-5000 hematology analyzer was performed on 463 PB samples from patients with different hematologic malignancies; the measured results were correlated with the manual nRBC count. Once the results were validated, complete blood count (CBC) with nRBC measurement was performed on 9272 sequential PB samples.
Results: Two hundred and eighty-one PB samples from patients with hematologic malignancies showed presence of nRBC by both manual and automated count. Nucleated RBC ranged from 1-390 per 100 WBC by manual count and 0.3-339 per 100 WBC by automated count with a correlation coefficient of 0.98. Among 9272 PB samples, nRBC were detected in 1228 samples (13.2%). Table 1 shows nRBC frequency and ranges when these PB samples were divided into three distinct groups.
|Samples with nRBCs||nRBC Range (per 100 WBC)||nRBC Range (x 10/uL)|
|PB samples with abnormal CBC morphology and parameters (n=1915)||761 (39.7%)||0.2-532.8||1-13611|
|PB samples without abnormal CBC morphology but with at least one parameter outside normal range (n=6283)||462 (7.4%)||0.2-3.5||1-20|
|PB samples with normal CBC morphology and parameters (n=1074)||5 (0.5%)||0.2-0.4||2-9|