Abnormal scattergrams and cell population data generated by fully automated hematological analyzers: New tools for screening malaria infection?

Reference intervals of cell population data parameters in Sysmex XN-Series and its patterns of changes from early adulthood to geriatric ages in South Korea

INTRODUCTION

Cell population data (CPD) parameters may be putative biomarkers for the screening of various diseases including some infections and myelodysplastic syndrome. This study aimed to establish the age- and sex-specific reference intervals (RIs) for the CPD parameters in the Korean population.

METHODS

The reference population for the RIs of CPD parameters comprised 124 856 subjects aged 20-99 years. CPD parameters were obtained from Sysmex XN-2000 (Kobe, Japan) datasets from 17 health promotion centers in 13 South Korean cities. We determined significant partitions for age and sex, and calculated RIs according to Clinical and Laboratory Standards Institute C28-A3 guidelines.

RESULTS

The side scattered light intensity in the neutrophil area and the lymphocyte area did not require sex-related partitioning except in those over the age of 50, among whom the lower limit (LL) and upper limit (UL) were lower in females. However, the side scattered light distribution width in the lymphocyte area required age- and sex-related partitioning, in which LL and UL were higher in females. The LL and UL of the fluorescent light distribution width were higher in males in the neutrophil area and higher in females in the lymphocyte area, but age-related partitioning was not required. The forward scattered light intensity in the neutrophil area, lymphocyte area, and monocyte area did not require age-related partitioning in males.

CONCLUSION

This study has determined comprehensive age- and sex-specific RIs for CPD parameters, which could help to prove the clinical significance of these parameters in the Sysmex XN-2000.

Pseudoreticulocytosis by the ADVIA 2120 Hematology Analyzer and Other Hematologic Changes in a Cynomolgus Macaque (Macaca fascicularis) With Malaria

Important hematologic changes can be observed in nonhuman primates with malaria, including inaccurate reticulocyte counts by the ADVIA 2120 hematology analyzer. A 5-year-old male purpose-bred cynomolgus macaque ( Macaca fascicularis) imported from a commercial source in Cambodia was enrolled in a nonclinical toxicity study investigating the effects of an immunomodulatory pharmaceutical agent. On study day 22, an increase in large unstained cells (LUCs), due to increased monocytes (2.20 × 103/µl, reference interval: 0.17-0.76 × 103/µl), was reported by the analyzer during a scheduled hematologic evaluation, which prompted blood smear review and revealed that the macaque had a high burden of Plasmodium spp.. The macaque did not have clinical signs for the infection at this time point. Progressively higher parasite burdens and persistently increased monocytes (markedly increased by study day 56, 10.38 × 103/µl) were observed at subsequent hematologic evaluations. New Methylene Blue stain manual reticulocyte counts were performed on study day 43 and at later time points, and showed that the analyzer reported erroneous higher reticulocyte counts (study day 43: +6.7%, +266.2 × 109/L; study day 50: +18.9%, +409.8 × 109/L) compared with the manual reticulocyte counts (pseudoreticulocytosis). The magnitude of regenerative response was considered inadequate for the severity of anemia at these time points. Atypical reticulocyte scatter plot distributions from the analyzer were also observed at time points with high parasite burdens, and combined with increased LUCs, may suggest high burden parasitemia. Verification of automated reticulocyte counts is important in cases with high malarial parasite burdens and the recognition of pseudoreticulocytosis is prudent in assessing appropriateness of the regenerative response. Increases in monocytes correlated with higher parasite burdens and marked increases may be an indicator of advanced disease.

Vivax malaria detection using a parasitic red blood cell flag generated by the Sysmex XN-9000 hematology analyzer

INTRODUCTION

A Sysmex XN-series hematology analyzer (Sysmex), the next generation up from the Sysmex XE-series, can provide information regarding malaria infection in the form of a parasitic red blood cell (pRBC) flag. This study aimed to determine the usefulness of the pRBC flag for early detection and follow-up in patients infected with Plasmodium vivax.

METHODS

A total of 221 patients with fever for whom CBC and malaria microscopy had been requested were analyzed. Sixty-seven individuals were diagnosed with P vivax infection, and 154 were diagnosed with other febrile diseases. The sensitivity and specificity of the pRBC flag for malaria parasite detection and the relationship between parasite density and presence of the pRBC flag were determined. The concordance rate between malaria microscopy and pRBC flag in 147 follow-up cases was calculated.

RESULTS

The pRBC flag was detected in 56 of 67 malaria patients (sensitivity, 83.6%; specificity, 100%). The patients with the pRBC flag at initial diagnosis revealed significantly higher parasite density than the patients without the pRBC flag (P < .05). The concordance rate between malaria microscopy and pRBC flag in the follow-up cases was 53.1%.

CONCLUSION

Considering its high sensitivity in malaria-suspicious patients, unexpected vivax malaria cases can be detected with the pRBC flag when CBC is done in a routine laboratory setting. The pRBC flag provided by the Sysmex XN series is a valuable tool for vivax malaria detection.

Leukocyte cell population data from the blood cell analyzer as a predictive marker for severity of acute pancreatitis

BACKGROUND

The prediction for severe acute pancreatitis (SAP) is the key to give timely targeted treatment. Leukocyte cell population data (CPD) have been widely applied in early prediction and diagnosis of many diseases, but their predictive ability for SAP remains unexplored. We aim to testify whether CPD could be an indicator of AP severity in the early stage of the disease.

METHODS

The prospective observational study was conducted in the emergency department ward of a territory hospital in Shanghai. The enrolled AP patients should meet 2012 Atlanta guideline.

RESULTS

Totally, 103 AP patients and 62 healthy controls were enrolled and patients were classified into mild AP (n = 30), moderate SAP (n = 42), and SAP (n = 31). Forty-two CPD parameters were examined in first 3 days of admission. Four CPD parameters were highest in SAP on admission and were constantly different among 3 groups during first 3 days of hospital stay. Eighteen CPD parameters were found correlated with the occurrence of SAP. Stepwise multivariate logistic regression analysis identified a scoring system of 4 parameters (SD_LALS_NE, MN_LALS_LY, SD_LMALS_MO, and SD_AL2_MO) with a sensitivity of 96.8%, specificity of 65.3%, and AUC of 0.87 for diagnostic accuracy on early identification of SAP. AUC of this scoring system was comparable with MCTSI, SOFA, APACHE II, MMS, BISAP, or biomarkers as CRP, PCT, and WBC in prediction of SAP and ICU transfer or death.

CONCLUSIONS

Several leukocyte CPD parameters have been identified different among MAP, MSAP, and SAP. They might be ultimately incorporated into a predictive system marker for severity of AP.

Performance evaluation of machine learning-based infectious screening flags on the HORIBA Medical Yumizen H550 Haematology Analyzer for vivax malaria and dengue fever

BACKGROUND

Automated detection of malaria and dengue infection has been actively researched for more than two decades. Although many improvements have been achieved, these solutions remain too expensive for most laboratories and clinics in developing countries. The low range HORIBA Medical Haematology Analyzer, Yumizen H550, now provides dedicated flags 'vivax malaria' and 'dengue fever' in routine blood testing, developed through machine learning methods, to be used as a screening tool for malaria and dengue fever in endemic areas. This study sought to evaluate the effectiveness of these flags under real clinical conditions.

METHODS

A total of 1420 samples were tested using the Yumizen H550 Haematology Analyzer, including 1339 samples from febrile patients among whom 202 were infected with malaria parasites (Plasmodium vivax only: 182, Plasmodium falciparum only: 18, both: 2), 210 were from febrile dengue infected patients, 3 were from afebrile dengue infected patients and 78 were samples from healthy controls, in an outpatient laboratory clinic in Mumbai, India. Microscopic examination was carried out as the confirmatory reference method for detection of malarial parasite, species identification and assessing parasitaemia based on different stages of parasite life cycle. Rapid diagnostic malarial antigen tests were used for additional confirmation. For dengue infection, NS1 antigen detection by ELISA was used as a diagnostic marker.

RESULTS

For the automated vivax malaria flag, the original manufacturer's cut off yielded a sensitivity and specificity of 65.2% and 98.9% respectively with the ROC AUC of 0.9. After optimization of cut-off value, flag performance improved to 72% for sensitivity and 97.9% specificity. Additionally it demonstrated a positive correlation with increasing levels of parasitaemia. For the automated dengue fever flag it yielded a ROC AUC of 0.82 with 79.3% sensitivity and 71.5% specificity.

CONCLUSIONS

The results demonstrate a possibility of the effective use of automated infectious flags for screening vivax malaria and dengue infection in a clinical setting.

An unusual case of sodium citrate-dependent artifactual platelet count

Background

Ethylenediaminetetraacetic acid (EDTA)-dependent pseudothrombocytopenia is a rare phenomenon. Spurious pseudothrombocytopenia has also been described in other circumstances, while artifactual platelet count in whole blood samples anticoagulated with sodium citrate is an exceptional occurrence.

Case report

In this study, we describe the case of a 44-year-old ostensibly healthy woman who attended the local outpatient clinic for routine laboratory testing, including platelet count in EDTA and sodium citrate, for suspected artifactual pseudothrombocytopenia previously identified in another center. The results of hematological testing on both specimens were essentially normal, except for mild anemia. Nevertheless, the platelet number was 425 × 10⁹/L in K₂EDTA and 266 × 10⁹/L (293 × 10⁹/L after correcting for sample dilution) in sodium citrate, respectively. Microscopic revision of blood smears revealed the presence of platelet aggregates and satellitism only in the sodium citrate specimen.

Conclusion

Unlike previous occasional reports of concomitant EDTA- and sodium citrate-dependent pseudothrombocytopenia, we first describe a paradigmatic case of artifactual platelet count attributable to platelet clumping and satellitism, exclusively developing in blood anticoagulated with sodium citrate.

Flagging performance of Sysmex XN-10 haematology analyser for malaria detection

Aim

The aim was to assess the flagging performance of Sysmex XN-10 haematology analyser for malaria detection through the parasitic red blood cell (‘pRBC’) alarm.

Methods

We retrospectively studied 584 blood samples performed on the Sysmex XN-10 analyser that were tested for malaria. Sensitivity, specificity, positive and negative predictive values, and prevalence were established for the pRBC alarm.

Results

Sensitivity, specificity, and positive and negative predictive values for the pRBC flag were 7.8%, 100%, 100% and 87.7%, respectively. The prevalence of pRBC flag of 0.026% in the overall population was significantly different from the prevalence of 1.027% in the population tested for malaria.

Conclusions

Considering the excellent specificity and the low prevalence of the flag in the overall population, we suggest, in case of the presence of pRBC flag, the implementation of a rapid review of the blood smear looking for Plasmodium, mostly if the patient had fever and had not been tested for malaria.