Report of the International Council for Standardization in Haematology working group for standardization of reticulocyte parameters

INTRODUCTION

The International Council for Standardization in Haematology convened a working group to assess and propose improvements upon the state of standardization and harmonization of reticulocyte parameters among commercial hematology analyzers.

METHODS

An international group of laboratory hematologists prospectively collected and analyzed clinical samples using locally available IVD commercial hematology analyzers. Eight hundred and fifty-five total samples were collected at 6 sites using 9 distinct analyzer types. Samples were assessed for reticulocyte percent (RET%), immature reticulocyte fraction (IRF), and reticulocyte hemoglobin content (RHC). Method comparison and regression statistics were calculated. These analyses were used to determine whether statistical recalibration offered a potential avenue for increasing comparability between these methods.

RESULTS

While methods producing reticulocyte percent were the most comparable in this study, the state of harmonization for the IRF and RHC was reduced with pearson correlation coefficients ranging from 0.955 to 0.77 and 0.927 and 0.680, respectively. Nevertheless, use of parameters from the Passing Bablok regression substantially improved the comparability of the results. In addition, precision data was derived which also demonstrated substantial differences between analyzer systems.

CONCLUSION

While reticulocyte counting is correlated between the automated methods evaluated in this study, the current state of harmonization of other reticulocyte parameters is not as strong. A major challenge in moving this field forward is the need for commutable materials to facilitate comparisons between analyzers not co-located. A potential alternate approach to improve the current state would be instrument re-calibration. However, this is challenging both technically and due to national regulatory frameworks.

The Immature Reticulocyte Fraction (IRF) in the Sysmex XN-1000V Analyzer Can Differentiate between Causes of Regenerative and Non-Regenerative Anemia in Dogs and Cats

The Sysmex XN-1000V analyzer can identify those reticulocytes with high RNA content and fluorescence, providing the immature reticulocyte fraction (IRF). While this parameter has been used in human medicine to identify the cause of anemia, few studies have focused on its use in veterinary medicine. In this study, we determined the IRF and related reticulocyte parameters in a large population of non-anemic and anemic dogs and cats (subclassified depending on the origin of their anemia). The IRF was significantly higher in hemolytic anemias compared to hemorrhagic ones in both species. Moreover, the IRF was significantly lower in dogs and cats with bone marrow failure than in other non-regenerative anemias and in both groups compared to pre-regenerative anemias. The accurate cut-off values for the differential in regenerative anemias and reference ranges for both species using the Sysmex XN-1000V are also reported. The measurement of the IRF in this analyzer can help clinicians to further classify the type of anemia in both species.

Reference intervals for reticulocyte indices, immature reticulocyte fraction, and the percentage of hypochromic red blood cells in adult large breed dogs using the ADVIA 2120 hematology analyzer

Reticulocyte indices are used to characterize anemia, including the identification of regeneration. In people, the immature reticulocyte fraction (IRF), percentage of hypochromic red blood cells (%HYPO-RBC), and other reticulocyte indices have been used as earlier indicators of erythropoiesis and as valuable monitoring tools in the assessment of various therapies. The reference intervals (RI) of the IRF and %HYPO-RBC have not been reported in dogs. The objective of this study was to establish RIs for novel variables (IRF, %HYPO-RBC, and CH-delta) and assess RIs for more commonly reported reticulocyte indices in healthy dogs. RIs were calculated from blood results retrospectively collected from 106 client-owned healthy dogs at the time of induction into a blood donor program using the ADVIA 2120 hematology analyzer (Siemens Healthcare Diagnostics). For the calculation of RIs, appropriate tests were applied for outlier detection and normality assessment. For variables normally distributed, RIs and their respective 90% confidence intervals (CIs) were calculated using parametric methods, while for variables not normally distributed, robust methods were used and bootstrapping for calculating the 90% CIs. The following RIs were established: reticulocyte hemoglobin content (CHr) 24.5-28 pg, mean reticulocyte volume (MCVr) 85.9-99.3 fL, mean corpuscular hemoglobin concentration of reticulocytes (CHCMr) 271.0-306.3 g/L, IRF 10.4%-43.5%, CH-delta 0.5-4.3 pg, and percentage of hypochromic red blood cells (%HYPO-RBC) 0.10%-0.80%. The results of this study provide RIs for novel reticulocyte variables. Further studies are required to determine the clinical utility of IRF, %HYPO-RBC, and CH delta as early indicators of erythropoietic activity in canine patients.

Assessment of Reticulocyte and Erythrocyte Parameters From Automated Blood Counts in Vaso-Occlusive Crisis on Sickle Cell Disease

Sickle cell disease is a complex genetic disease involving cell adhesion between red blood cells, white blood cells, platelets and endothelial cells, inducing painful vaso-occlusive crisis (VOC). We assessed reticulocyte and erythrocyte parameters in a cohort of confirmed SCD patients, and investigated whether a combination of these routine laboratory biomarkers of haemolysis could be used to predict VOC development. Reticulocyte and erythrocyte parameters were evaluated using the Sysmex XN-9000 analyser. A total of 98 patients with SCD were included, 72 in steady state and 26 in VOC. Among the 72 patients in steady state, 22 developed a VOC in the following year (median: 3 months [2-6]). The following parameters were increased in SCD patients with VOC development compared to SCD patients without VOC development in the following year: reticulocyte count (94.6 10⁹/L [67.8-128] vs. 48.4 10⁹/L [24.9-87.5]), immature reticulocyte count (259 10⁹/L [181-334] vs. 152 10⁹/L [129-208]) reticulocyte/immature reticulocyte fraction (IRF) ratio (6.63 10⁹/(L^*%) [4.67-9.56] vs. 4.94 10⁹/(L^*%) [3.96-6.61]), and medium fluorescence reticulocytes (MFR) (19.9% [17.4-20.7] vs. 17.1% [15.95-19.75]). The association of a reticulocyte count of >189.4 10⁹/L and an MFR of >19.75% showed a sensitivity of 81.8% and a specificity of 88% to predict VOC development in the following year. Based on our findings, a combination of routine laboratory biomarkers, as reticulocyte count, immature reticulocyte count and fluorescent reticulocyte fraction at steady state, could be used to predict VOC development in SCD.

Comparison of the value of immature retyculocyte and immature platelet in the diagnosıs of sepsis

BACKGROUND

Sepsis is one of the causes of pre-treatment morbidity and mortality in the pediatric age group. In the present study, we investigated the place of the immature granulocyte percentage, (IG) immature reticulocyte fraction (IRF), and immature platelet fraction (IPF) in the diagnosis of sepsis.

METHODS

Complete blood count, C-reactive protein, (CRP) procalcitonin (PCT) and blood cultures were measured in 125 critical patients who were followed-up in the intensive care unit with the suspicion of sepsis and 65 healthy children between 2017 and 2019. In addition to the complete blood counts and routine parameters, IG, IRF, and IPF were examined in the patients.

RESULTS

When the critical patient group and the healthy control group were compared, it was found that the total number of leukocytes (white blood cells), neutrophil count, platelet count, CRP, PCT, IG, IRF, and IPF values were higher at statistically significant levels. When septic and non-septic patients were compared, it was found that the CRP, PCT,IGP, and IPF were higher at statistically significant levels in the septic patients.

CONCLUSIONS

It was concluded that CRP, PCT, IG, and IPF were significant in determining sepsis and that PCT was the most sensitive and specific biomarker in these parameters. We believe that these parameters may be suitable for practical use in determining sepsis because they give faster results and suggest the diagnosis of sepsis.

Reference intervals of automated reticulocyte count and immature reticulocyte fraction in a pediatric population

INTRODUCTION

Reticulocytes are erythroid precursors that develop into mature erythrocytes, and they are an important tool to assess erythropoietic activity, as their count indicates the balance between the cells released from the bone marrow, their stage of maturity, and their rate of development into mature erythrocytes. Considering the described biological variability of the absolute reticulocyte count (ARC) and the immature reticulocyte fraction (IRF) and the limited information available on these hematological parameters in children, this study determined the reference intervals (RIs) of these parameters in a healthy pediatric population.

METHODS

A retrospective, observational, and analytical study was designed to establish RIs for the ARC and the IRF according to age and sex. An indirect sampling method was applied to a mixed database of complete blood counts from children aged 2 months to 18 years, using the truncated maximum likelihood indirect method for reference interval estimation. Percentiles were calculated to obtain bimodal RIs.

RESULTS

From a total of 190,812 samples, 6,814 were selected. Gender stratification was not necessary for the ARC and the IRF but they required partitioning into six and two age groups, respectively.

CONCLUSION

This study determined, by an indirect sampling method, RIs for the ARC and the IRF in a pediatric population according to age and sex.

Utility of reticulocyte haemoglobin content and immature reticulocyte fraction in early diagnosis of latent iron deficiency in whole blood donors

BACKGROUND AND OBJECTIVES

The present study was planned to assess the clinical utility of reticulocyte haemoglobin content (CHr) and immature reticulocyte fraction (IRF) in the early detection of latent iron deficiency in blood donors.

MATERIALS AND METHODS

The prospective longitudinal observational study was conducted using the purposive sampling method. Written informed consent was obtained and donors were allocated into the first-time (FTD) and regular donor (RD) group. The enrolled blood donors (n = 205 in each group) were followed up for two subsequent whole blood donations. Haemoglobin (Hb), CHr, IRF and serum ferritin values were recorded at enrolment and two follow-ups.

RESULTS

The sensitivity of CHr in detecting iron-deficient erythropoiesis (serum ferritin values ≤ 26 μg/dl) was 45% and 56.7%, specificity 96.7%, positive predictive value (PPV) 85.6% and 90.8% and negative predictive value (NPV) 80.1% and 78.7%, respectively in FTD and RD cohorts. The sensitivity of IRF was 45.1% and 44.8%, specificity 93.4% and 97.1%, PPV 74.8% and 90.4% and NPV 79.6% and 74.5%, respectively in both the cohorts. The sensitivity of CHr in detecting absent iron stores (serum ferritin values ≤ 15 μg/dl) was 66.2% and 74.4%, specificity 92% and 90.6%, PPV 56.7% and 68.7% and NPV 94.5% and 92.8% among FTD and RD cohort, respectively. The sensitivity of IRF was 72.7% and 65.3%, specificity 90.3% and 94.3%, PPV 54.4% and 76% and NPV 95.4% and 90.8%, respectively in both the cohorts.

CONCLUSION

Reticulocyte hemoglobin content and IRF can be used along with complete blood count for early detection of iron deficiency in blood donors using the same blood sample at no extra cost.

Immature cell fractions after cessation of chronic P2Y12-inhibition in patients with coronary artery diseases

Changes in circulating cell populations may promote ischemic events that occur soon after discontinuation of P2Y₁₂-inhibition. The aim of the study was to track the course of thrombopoietic and erythropoietic cells in patients with coronary artery diseases (CAD) after planned and physician-driven cessation of chronic P2Y₁₂-inhibition (clopidogrel 75 mg OD, or prasugrel 10 mg OD, or ticagrelor 90 mg BID). Cell fractions were determined in 62 patients at baseline (the last day of P2Y₁₂-inhibitor intake), on day-10, day-30, and day-180 thereafter. Immature platelet fraction (IPF), immature reticulocyte fraction (IRF), reticulocyte hemoglobin content (Ret-Hb) and red blood cell count (RBC) significantly increased from baseline to day-180 (IPF: p = .003; IRF: p = .013; Ret-Hb: p < .001; RBC: p = .044). Platelet count, leucocyte count and immature granulocyte fraction did not change over time (p = .561, p = .869, and p = .161, respectively). Fibrinogen levels significantly declined over time (p = .011), thrombopoietin levels increased in a non-significant manner (p = .379). We did not observe any significant interaction with choice of P2Y₁₂-inhibitor, therefore suggesting a drug class-effect. Our data shows, that discontinuation of dual antiplatelet therapy is associated with raised thrombopoietic and erythropoietic activity in the bone marrow, without significant upregulation of thrombopoietin. This provides further evidence for a direct stimulation of precursor cells by P2Y_12-inhibitors.

Role of Reticulocyte Parameters in Anemia of First Trimester Pregnancy: A Single Center Observational Study

Introduction  The diagnosis of anemia in pregnancy should be early to prevent complications to mother and baby. It should be simple and safe, and therefore feasibility of reticulocyte parameters may prove beneficial in this regard. Newer reticulocyte parameters have not been studied extensively especially in pregnancy. The present study was conducted to evaluate reticulocyte hemoglobin content (Ret-He), immature reticulocyte fraction, and reticulocyte count and to compare them with serum ferritin, mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) in assessment anemia in pregnancy. Material and Methods  Prospective study included first trimester pregnant females where hemoglobin, MCV, and MCH were categorized and statistically analyzed with serum ferritin and reticulocyte parameters. Results  The study included 155 first trimester pregnant females showing statistical difference in Ret-He between all categories of hemoglobin and MCV ( p < 0.05). ROC curve analysis using MCV < 83 fl and MCH <27 pg showed that area under curve for Ret-He at cutoff of 27.8 ng/mL was 0.93 (95% confidence interval 0.90-0.98, sensitivity 93%, specificity 83%). The cutoff of 27.2 ng/mL Ret-He for the diagnosis of iron deficiency anemia has specificity of 86%, sensitivity 71%, positive predictive value 0.39, and likelihood ratio of 5.1. Conclusion  Ret-He is a feasible and easily available parameter which may be helpful in differentiating between microcytic hypochromic and normocytic normochromic anemia along with frank and borderline anemia in first trimester pregnant females. This in turn is essential to initiate an early therapy so as to prevent the maternal and fetal complications.

Laboratory diagnosis of anemia: are the old and new red cell parameters useful in classification and treatment, how?

INTRODUCTION

Anemia is a global problem affecting the population in both developing and developed countries, and there is a debate on which hemoglobin level limit should be used to define anemia in general population and particularly in the elderly. We present herein a laboratory approach to diagnosing the possible causes of anemia based on traditional and new erythroid parameters. In this article, we provide practical diagnostic algorithms that address to differential diagnosis of anemia. Based on both morphological and kinetic classifications, three patterns were considered: microcytic, normocytic, and macrocytic.

METHODS

Main interest is on the clinical usefulness of old and new parameters such as mean cell volume (MCV), red blood cell distribution width (RDW), hypochromic and microcytic erythrocytes, immature reticulocyte fraction (IRF), and some reticulocyte indices such as reticulocyte hemoglobin content and mean reticulocyte volume. The pathophysiologic basis is reviewed in terms of bone marrow erythropoiesis, evaluated by reticulocyte count (increased or normal/decreased) and IRF. The utility of reticulocyte indices in the diagnosis of iron-deficient erythropoiesis (absolute or functional) and in monitoring of response to treatment in nutritional anemia (iron and cobalamin) was also investigated.

RESULTS

For each parameter, the availability, the possible clinical applications, and the limitations were evaluated. A discussion on intraindividual biological variation and its implication on the usefulness of conventional reference intervals and in longitudinal monitoring of the patients was also reported.

CONCLUSION

Red cell parameters and reticulocyte indices play an essential role in differential diagnosis of anemia and in its treatment. More efforts are needed in harmonizing parameters whose results are still too different when produced by different analyzers.