The Presence of Nucleated Red Blood Cells as an Indicator for Increased Mortality and Morbidity in Burn Patients

Comparison Evaluation of Automated Nucleated Red Blood Cell Enumeration by Sysmex XN 1000 in Comparison With Microscopic Reference in Children Under 1 Year

BACKGROUND

In newborns, elevated nucleated red blood cell (NRBC) levels can be associated with enhanced erythropoietic stress and might be predictive for adverse outcome. Also, the presence of NRBC in peripheral blood might lead to erroneous enumeration results of white blood cells in automated hematology analyzers. We aimed to assess the comparability of the Sysmex XN 1000 to manual slide reviews and correlation of NRBC with inflammation markers.

METHODS

Specimens of 3397 children under 1 year were compared by automated and microscopic NRBC enumeration. Additionally, potential correlations between NRBC and age and inflammation markers were examined.

RESULTS

Overall, there was good correlation (r = 0.97) between automated (range: 0%-3883%) and microscopic enumeration (range: 0%-3694%) of NRBC with high comparability up to a NRBC value of 200% and an increase in the variation between the two methods with increasing NRBC numbers. When 94 samples with ≤ 200% NRBC and ≥ 30% divergence between methods were separately reanalyzed with respect to overlapping cell populations in their scattergrams, Sysmex would have generated unrecognized incorrect automated results in 47 samples, corresponding to 1.4% of total study samples. NRBC counts were negatively correlated to age, but not to inflammation markers.

CONCLUSION

Sysmex XN 1000 is highly precise in the enumeration of NRBC in children under 1 year up to counts of 200% and might replace time-intense manual counting in routine diagnostics. In the setting of neonatal and intensive care diagnostics, microscopic control and supervision of scattergrams are highly recommended for any automated NRBC enumeration processes.

Influence of hemolysis on nucleated red blood cells count

INTRODUCTION

Hemolysis is a common pre-analytical factor that can influence test results. Here, we explored the influence of hemolysis on nucleated red blood cells (NRBCs) count and tried to illustrate the mechanisms underlying this interference.

METHODS

From July 2019 to June 2021, 20 preanalytical hemolytic peripheral blood (PB) samples from inpatient at Tianjin Huanhu Hospital were evaluated using Sysmex XE-5000 automated hematology analyzer. When NRBC enumeration was positive and a flag was triggered, a 200-cell differential count was performed by experienced technologists on microscopic review. When the manual count was inconsistent with automated enumeration, samples will be re-collected. Plasma exchange test was performed to verify the influence factors of hemolyzed samples and the mechanical hemolysis experiment mimicking hemolysis that might occur during blood collection was performed to illustrate the underlying mechanisms.

RESULTS

Hemolysis led to false-positive NRBC count and the value of NRBC was positively correlated with the degree of hemolysis. Hemolysis specimen shared a common scatter diagram: a "beard" on WBC/ basophil (BASO) channel and a "blue scatter line" on immature myeloid information (IMI) channel. Lipid droplets were found above the hemolysis specimen after centrifugation. Plasma exchange experiment confirmed that these lipid droplets interfered with NRBCs count. Mechanical hemolysis experiment implied further that broken red blood cells (RBCs) released lipid droplets causing the false-positive NRBCs count.

CONCLUSION

In the present study, we firstly found that hemolysis could lead to false-positive NRBCs enumeration, which was associated with lipid droplets released from broken RBCs during hemolysis.