Fragmented red blood cells automated measurement is a useful parameter to exclude schistocytes on the blood film.
BACKGROUND
The diagnosis of thrombotic microangiopathies (TMA) or disorders that may mimic their features remains difficult. Mechanical hemolytic anemia with the detection of shistocytes on the blood smear is a cornerstone finding to assess the diagnosis, but microscopic evaluation of shistocytes is still problematic with wide interobserver variations. Some of the latest generation automated blood cell counters (ABCC) propose an original quantitative approach of fragmented red cells (FRC), aiming to be equivalent to the microscopic count. This parameter has been poorly evaluated.


METHODS
To assess the predictive value (PV) of this test, we conducted studies comparing automated and microscopic counts of FRC/schistocytes, based on the analysis of thousands samples in four university hospitals and using the 2 ABCC currently available (Siemens ADVIA series, Sysmex XE-2100).


RESULTS
Reference range for FRC was <0.3% for the ADVIA and <0.5% for the XE-2100. The presence of FRC below a threshold determined at 1% (ADVIA and XE-2100) had a negative PV close to 100% to exclude the presence of schistocyte on the blood smear, but in relationship with a poor PV value.


CONCLUSIONS
Our study validated the utility of the immediately available FRC parameter on ABCC to exclude schistocytes and the diagnosis of TMA.
Laboratory of Hematology, University Hospital, Nancy, FranceLaboratory of Hematology, Hospital Necker - Enfants malades, Paris, FranceLaboratory of Hematology, Hospital Center, Thionville, FranceHematology Laboratory, Catholic University of Sacred Heart, Rome, ItalyResearch Center for Automated Hematology (ReCamh), Roma, Italy.
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Lesesve
Laboratory of Hematology, University Hospital, Nancy, FranceLaboratory of Hematology, Hospital Necker - Enfants malades, Paris, FranceLaboratory of Hematology, Hospital Center, Thionville, FranceHematology Laboratory, Catholic University of Sacred Heart, Rome, ItalyResearch Center for Automated Hematology (ReCamh), Roma, Italy.
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Asnafi
Laboratory of Hematology, University Hospital, Nancy, FranceLaboratory of Hematology, Hospital Necker - Enfants malades, Paris, FranceLaboratory of Hematology, Hospital Center, Thionville, FranceHematology Laboratory, Catholic University of Sacred Heart, Rome, ItalyResearch Center for Automated Hematology (ReCamh), Roma, Italy.
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Braun
Laboratory of Hematology, University Hospital, Nancy, FranceLaboratory of Hematology, Hospital Necker - Enfants malades, Paris, FranceLaboratory of Hematology, Hospital Center, Thionville, FranceHematology Laboratory, Catholic University of Sacred Heart, Rome, ItalyResearch Center for Automated Hematology (ReCamh), Roma, Italy.
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Zini
D000328:Adult; D057205:Automation, Laboratory; D004906:Erythrocyte Count / Q000295:instrumentation* / Q000379:methods*; D004913:Erythrocytes, Abnormal / Q000166:cytology*; D006801:Humans; D007231:Infant, Newborn; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D057049:Thrombotic Microangiopathies / Q000097:blood / Q000175:diagnosis