Use of reticulocyte cellular indices in the diagnosis and treatment of hematological disorders

Reticulocyte hemoglobin equivalent as a marker to assess iron deficiency: A large pediatric tertiary care hospital study

INTRODUCTION

Detection of iron deficiency (ID) remains challenging. We aimed to evaluate the performance of reticulocyte hemoglobin equivalent (Ret-He) as a potential diagnostic marker to assess ID and iron deficiency anemia (IDA) in a large pediatric cohort.

METHODS

A total of 3158 patients (aged 15 days to 19 years with a median age of 8.5 years; 60.2% female) were retrospectively studied. Statistical analysis was performed (a) to evaluate relationship of Ret-He with other relevant complete blood count and iron panel parameters; (b) to compare the levels of Ret-He in ID and IDA groups to a control group; and (c) to assess sensitivity and specificity of Ret-He in ID, IDA, and anemia without ID groups.

RESULTS

Ret-He values were significantly positively correlated to ferritin and transferrin saturation (TSAT). The median Ret-He was significantly lower in ID. A Ret-He cutoff of ≤30.0 pg distinguished cases of ID from the control group with a sensitivity of 90.2%, specificity of 59.5%, and area under curve (AUC) of 0.88. Ret-He showed better diagnostic performance in the IDA group and acceptable performance for ID without anemia. The sensitivity, specificity, and AUC were 90.1%, 80.9%, and 0.93 for IDA at cutoff value of ≤27.4 pg, and 80.8%, 51.1%, and 0.70 for ID without anemia at cutoff value of ≤30.8 pg, respectively.

CONCLUSION

Our large pediatric tertiary care hospital study demonstrates that Ret-He is a reliable marker to help confirm IDA in pediatric population. However, further studies are needed for its use to capture the early stages of ID.

The Reticulocyte Hemoglobin Equivalent as a Screening Marker for Iron Deficiency and Iron Deficiency Anemia in Children

Background: Iron deficiency (ID) is one of the most common nutritional deficiencies in children worldwide and may result in iron deficiency anemia (IDA). The reticulocyte hemoglobin equivalent (Ret-He) provides information about the current availability of iron in erythropoiesis. This study aims to examine the validation of Ret-He as a screening marker for ID and IDA in children. Methods: Blood samples were retrospectively obtained from medical records. Anemia was defined according to the definition provided by the World Health Organization (WHO) for children. ID was defined by transferrin saturation (TSAT) < 20% and ferritin < 100 ng/mL. Children were classified into four groups: IDA, non-anemia iron deficiency (NAID), control and others. Results: Out of 970 children, 332 (34.2%) had NAID and 278 (28.7%) presented with IDA. Analysis revealed that Ret-He significantly correlates with ferritin (rho = 0.41; p < 0.001), TSAT (rho = 0.66; p < 0.001) and soluble transferrin receptor (sTfR) (rho = −0.72; p < 0.001). For ROC analysis, the area under the curve (AUC) was 0.771 for Ret-He detecting ID and 0.845 for detecting IDA. The cut-off value for Ret-He to diagnose ID was 33.5 pg (sensitivity 90.7%; specificity 35.8%) and 31.6 pg (sensitivity 90.6%; specificity 50.4%) to diagnose IDA. Conclusions: The present study demonstrates Ret-He to be a screening marker for ID and IDA in children. Furthermore, Ret-He can be used as a single screening parameter for ID and IDA in children without considering other iron parameters. Economically, the use of Ret-He is highly relevant, as it can save one blood tube per patient and additional costs.

Cell Mechanics Based Computational Classification of Red Blood Cells Via Machine Intelligence Applied to Morpho-Rheological Markers

Despite fluorescent cell-labelling being widely employed in biomedical studies, some of its drawbacks are inevitable, with unsuitable fluorescent probes or probes inducing a functional change being the main limitations. Consequently, the demand for and development of label-free methodologies to classify cells is strong and its impact on precision medicine is relevant. Towards this end, high-throughput techniques for cell mechanical phenotyping have been proposed to get a multidimensional biophysical characterization of single cells. With this motivation, our goal here is to investigate the extent to which an unsupervised machine learning methodology, which is applied exclusively on morpho-rheological markers obtained by real-time deformability and fluorescence cytometry (RT-FDC), can address the difficult task of providing label-free discrimination of reticulocytes from mature red blood cells. We focused on this problem, since the characterization of reticulocytes (their percentage and cellular features) in the blood is vital in multiple human disease conditions, especially bone-marrow disorders such as anemia and leukemia. Our approach reports promising label-free results in the classification of reticulocytes from mature red blood cells, and it represents a step forward in the development of high-throughput morpho-rheological-based methodologies for the computational categorization of single cells. Besides, our methodology can be an alternative but also a complementary method to integrate with existing cell-labelling techniques.

Quantifying the influences of radiation therapy on deformability of human red blood cells by dual-beam optical tweezers

Radiation therapy is widely used as a treatment tool for malignancies. However, radiation-related complications are still unavoidable risks for off-target cells. Little is known about radiation therapy's possible effects on mechanical features of the off-target cells such as human red blood cells (RBCs). RBCs are nucleus-free circulating cells that can deform without losing functionality in healthy conditions. Thus, to evaluate in vitro effects of radiation therapy on the healthy plasma membrane of cells, RBCs were selected as a primary test model. RBCs were exposed to clinically prescribed radiotherapy doses of 2 Gy, 12 Gy and, 25 Gy, and each radiotherapy dose group was compared to a non-irradiated group. Cells were characterized by stretching using dual-beam optical tweezers and compared using the resulting deformability index. The group receiving the highest radiation dose was found statistically distinguishable from the control group (DI_0Gy = 0.33 ± 0.08), and revealed the highest deformability index (DI_25Gy = 0.38 ± 0.11, p = 0.0068), while no significant differences were found for 2 Gy (DI_2Gy = 0.33 ± 0.08, p = 0.9) and 12 Gy (DI_12Gy = 0.31 ± 0.09, p = 0.2) dose groups. Based on these findings, we conclude that radiotherapy exposure may alter the deformability of red blood cells depending on the dose amount, and measurement of deformability index by dual-beam optical tweezers can serve as a sensitive biomarker to probe responses of cells to the radiotherapy.

Little is known about radiation therapy's possible effects on mechanical features of off-target cells such as human red blood cells. Here, irradiated human red blood cells were stretched using dual-beam optical tweezers and compared using the resulting deformability index.

Microfluidic label-free bioprocessing of human reticulocytes from erythroid culture

In vitro erythroid cultures from human hematopoietic stem cells produce immature red blood cells (RBCs) called reticulocytes, which are important for RBCs production, and are widely used in scientific studies of malaria pathology, hematological diseases and protein translation. However, in vitro reticulocyte cultures contain expelled cell nuclei and erythroblasts as undesirable by-products and current purification methods such as density gradient centrifugation and fluorescence-activated cell sorting (FACS) are not optimal for integrated bioprocessing and downstream therapeutic applications. Developments in Dean flow fractionation (DFF) and deterministic lateral displacement (DLD) microfluidic sorting methods are ideal alternatives due to label-free size sorting, throughput scalability and low manufacturing cost. DFF sorting of reticulocytes from whole erythroid culture showed a 2.4-fold increase in cell recovery compared to FACS albeit with a lower purity; DLD sorting showed comparable cell recovery and purity with FACS using an inverse-L pillar structure to emphasize size and deformability sorting of reticulocytes. The viability and functional assurance of purified reticulocytes showed conserved cell deformability and supported the propagation of malaria parasites. Collectively, our study on label-free RBCs isolation represents a significant technical advancement towards developing in vitro generated viable human RBCs, opening opportunities for close-loop cell manufacturing, downstream therapeutic and research purposes.

Diagnosis of anemia-A synoptic overview and practical approach

Anemia is common in everyday clinical practice. In the following, the characteristics of apparently proven as well as new biomarkers are presented - for diagnosis and therapy control, considering their diagnostic value. In spite of new diagnostic tools, the importance of microscopy in hematological manifestations is illustrated. Based on a classification of anemia, a strategy is proposed for an economic diagnosis of different types of anemia and their predisposition.

Analysis of erythrocyte dynamics in Rhesus macaque monkeys during infection with Plasmodium cynomolgi

BACKGROUND

Malaria is a major mosquito transmitted, blood-borne parasitic disease that afflicts humans. The disease causes anaemia and other clinical complications, which can lead to death. Plasmodium vivax is known for its reticulocyte host cell specificity, but many gaps in disease details remain. Much less is known about the closely related species, Plasmodium cynomolgi, although it is naturally acquired and causes zoonotic malaria. Here, a computational model is developed based on longitudinal analyses of P. cynomolgi infections in nonhuman primates to investigate the erythrocyte dynamics that is pertinent to understanding both P. cynomolgi and P. vivax malaria in humans.

METHODS

A cohort of five P. cynomolgi infected Rhesus macaques (Macaca mulatta) is studied, with individuals exhibiting a plethora of clinical outcomes, including varying levels of anaemia. A discrete recursive model with age structure is developed to replicate the dynamics of P. cynomolgi blood-stage infections. The model allows for parasitic reticulocyte preference and assumes an age preference among the mature RBCs. RBC senescence is modelled using a hazard function, according to which RBCs have a mean lifespan of 98 ± 21 days.

RESULTS

Based on in vivo data from three cohorts of macaques, the computational model is used to characterize the reticulocyte lifespan in circulation as 24 ± 5 h (n = 15) and the rate of RBC production as 2727 ± 209 cells/h/µL (n = 15). Analysis of the host responses reveals a pre-patency increase in the number of reticulocytes. It also allows the quantification of RBC removal through the bystander effect.

CONCLUSIONS

The evident pre-patency increase in reticulocytes is due to a shift towards the release of younger reticulocytes, which could result from a parasite-induced factor meant to increase reticulocyte availability and satisfy the parasite's tropism, which has an average value of 32:1 in this cohort. The number of RBCs lost due to the bystander effect relative to infection-induced RBC losses is 62% for P. cynomolgi infections, which is substantially lower than the value of 95% previously determined for another simian species, Plasmodium coatneyi.

Reticulocyte hemoglobin content (MCHr) in the assessment of iron deficient erythropoiesis in inflammatory bowel disease

BACKGROUND

In conditions associated with inflammation, biochemical parameters alone could be inadequate for assessing iron status. We investigated the potential utility of mean reticulocyte hemoglobin content (MCHr) in the assessment of the erythropoiesis status in inflammatory bowel disease (IBD).

METHODS

We recruited 124 anemic outpatients with IBD. Serum iron, transferrin and ferritin were tested. Complete blood counts were performed on a CELL-DYN Sapphire analyzer (Abbott Diagnostics). Differences among groups were assessed using analysis of variance, considering P < 0.05 to be significant. Receiver operating characteristic analysis was used to assess the diagnostic performance of MCHr for detecting iron deficient erythropoiesis. The reference used as an indicator of insufficient iron availability was transferrin saturation <20%.

RESULTS

Overall, 47.6% of the patients had iron deficiency anemia (IDA) and 31.5% anemia of chronic disease (ACD), while the others (20.9%) had mixed anemia. Patients with ACD or mixed anemia showed functional iron deficiency: normal or high ferritin and low MCHr. The area under curve was 0.858 (95% CI 0.742-0.942), considering a cut off 30.3 pg, the sensitivity was 82.2%, specificity 83.3%.

CONCLUSIONS

MCHr provides information on iron availability in IBD patients. It is a reliable test to assess iron supply for erythropoiesis.

Plasma vitamin C levels in ESRD patients and occurrence of hypochromic erythrocytes

INTRODUCTION

The achievement of erythropoiesis in hemodialysis (HD) patients is typically managed with erythropoiesis-stimulating-agents (ESA's) and intravenous iron (IV-iron). Using this treatment strategy, HD patients frequently show an elevated fraction of red blood cells (RBC) with hemoglobin (Hb) content per cell that is below the normal range, called hypochromic RBC. The low Hb content per RBC is the result of the clinical challenge of providing sufficient iron content to the bone marrow during erythropoiesis. Vitamin C supplements have been used to increase Hb levels in HD patients with refractory anemia, which supports the hypothesis that vitamin C mobilizes iron needed for Hb synthesis.

METHODS

We conducted a cross-sectional survey in 149 prevalent HD patients of the percent hypochromic RBC, defined as RBC with Hb < 300 ng/uL of packed RBC, in relation to plasma vitamin C levels. We also measured high-sensitivity CRP, (hs-CRP), iron, and ferritin levels. and calculated ESA dose.

FINDINGS

High plasma levels of vitamin C were negatively associated with hypochromic RBC (P < 0.003), and high ESA doses were positively associated (P < 0.001). There was no significant association of hs-CRP with percent hypochromic RBC.

DISCUSSION

This finding supports the hypothesis that vitamin C mobilizes iron stores, improves iron delivery to the bone marrow, and increase the fraction of RBC with normal Hb content. Further research is warranted on development of protocols for safe and effective use of supplemental vitamin C for management of renal anemia.

Determination of reference ranges for immature platelet and reticulocyte fractions and reticulocyte hemoglobin equivalent

Introduction

The immature platelet and immature reticulocyte fractions represent the ratios of platelets and reticulocytes recently released into the circulation and thus with higher RNA content. They are considered early indicators of bone marrow recovery.

Objective

The aim of this study was to determine the reference ranges for the immature platelet and reticulocyte fractions of hematologically normal individuals in a university hospital.

Methods

Venous blood samples collected in ethylenediaminetetraacetic acid K3 were analyzed using a Sysmex XE-5000™ analyzer. Individuals with platelet and reticulocyte counts within the reference ranges, and a blood count within the laboratory's screening criteria were included. Individuals with clinical conditions that could affect hematological results were excluded. The immature platelet fraction, high, medium and low fluorescence reticulocyte fractions and reticulocyte hemoglobin equivalent were evaluated. The reference ranges were determined according to the recommendations of the International Federation of Clinical Chemistry.

Results

One hundred and thirty-two outpatients were evaluated. The mean age was 44 years (range: 13–80 years), 72 (54.5%) were women treated in a university hospital. The mean platelet count was 250.8 × 10⁹/L and the mean reticulocyte count was 0.052 × 10⁹/L. The following reference ranges were obtained: immature reticulocyte fraction 1.6–12.1%, the high, medium and low fluorescence reticulocyte fractions were 0.0–1.7%, 1.6–11.0% and 87.9–98.4%, respectively, the reticulocyte hemoglobin equivalent was 30.0–37.6% and immature platelet fraction was 0.8–5.6%. There was a statistically significant difference (p-value = 0.006) between genders in respect to the immature platelet fraction with 0.8–4.7% for females and 0.7–6.1% for males. The immature reticulocyte fraction was directly correlated with the reticulocyte count.

Conclusion

Determining the reference range is critical to the introduction of a new parameter. The reference ranges obtained herein corroborate those reported in previous publications and will contribute to the clinical and laboratory application of the indices.

Dietary supplementation with docosahexanoic acid (DHA) increases red blood cell membrane flexibility in mice with sickle cell disease

Humans and mice with sickle cell disease (SCD) have rigid red blood cells (RBCs). Omega-3 fatty acids, such as docosahexanoic acid (DHA), may influence RBC deformability via incorporation into the RBC membrane. In this study, sickle cell (SS) mice were fed natural ingredient rodent diets supplemented with 3% DHA (DHA diet) or a control diet matched in total fat (CTRL diet). After 8weeks of feeding, we examined the RBCs for: 1) stiffness, as measured by atomic force microscopy; 2) deformability, as measured by ektacytometry; and 3) percent irreversibly sickled RBCs on peripheral blood smears. Using atomic force microscopy, it is found that stiffness is increased and deformability decreased in RBCs from SS mice fed CTRL diet compared to wild-type mice. In contrast, RBCs from SS mice fed DHA diet had markedly decreased stiffness and increased deformability compared to RBCs from SS mice fed CTRL diet. Furthermore, examination of peripheral blood smears revealed less irreversibly sickled RBCs in SS mice fed DHA diet as compared to CTRL diet. In summary, our findings indicate that DHA supplementation improves RBC flexibility and reduces irreversibly sickled cells by 40% in SS mice. These results point to potential therapeutic benefits of dietary omega-3 fatty acids in SCD.

Accuracy of the CellaVision DM96 platform for reticulocyte counting

CONTEXT

Many hematology laboratories have adopted semi-automated digital platforms for routine use and the evidence supporting their use is increasing.

AIMS

The CellaVision platforms are among the most thoroughly studied digital hematology platforms; we wished to determine the accuracy of CellaVision for reticulocyte counting.

DESIGN MATERIALS AND METHODS

We compared reticulocyte counts performed manually, using the Beckman Coulter LH750 automated analyzer and with the CellaVision DM96 platform. We analyzed the results for pair-wise correlation and bias, and precision.

STATISTICAL ANALYSES USED

Analyses were performed using Statistical Package for the Social Sciences software (SPSS), including Spearman's rho correlation coefficient, Friedman's two-way Analysis Of Variance (ANOVA) for comparison of distributions; bias was compared by way of mean and standard deviation.

RESULTS

The CellaVision reticulocyte counts correlated most strongly with those of the analyzer (often considered the benchmark test); the reticulocyte count distributions were noted not to be significantly different from each other across all three methods. The mean and standard deviation of bias were lowest in the comparison of CellaVision and LH750 counts.

CONCLUSIONS

Our data provide additional support for the accuracy of digital hematology applications using the CellaVision DM96 platform.

Strain-specific variations in cation content and transport in mouse erythrocytes

Studies of ion transport pathophysiology in hematological disorders and tests of possible new therapeutic agents for these disorders have been carried out in various mouse models because of close functional similarities between mouse and human red cells. We have explored strain-specific differences in erythrocyte membrane physiology in 10 inbred mouse strains by determining erythrocyte contents of Na(+), K(+), and Mg(2+), and erythrocyte transport of ions via the ouabain-sensitive Na-K pump, the amiloride-sensitive Na-H exchanger (NHE1), the volume and chloride-dependent K-Cl cotransporter (KCC), and the charybdotoxin-sensitive Gardos channel (KCNN4). Our data reveal substantial strain-specific and sex-specific differences in both ion content and trans-membrane ion transport in mouse erythrocytes. These differences demonstrate the feasibility of identifying specific quantitative trait loci for erythroid ion transport and content in genetically standardized inbred mouse strains.

Compromised mitochondrial fatty acid synthesis in transgenic mice results in defective protein lipoylation and energy disequilibrium

A mouse model with compromised mitochondrial fatty acid synthesis has been engineered in order to assess the role of this pathway in mitochondrial function and overall health. Reduction in the expression of mitochondrial malonyl CoA-acyl carrier protein transacylase, a key enzyme in the pathway encoded by the nuclear Mcat gene, was achieved to varying extents in all examined tissues employing tamoxifen-inducible Cre-lox technology. Although affected mice consumed more food than control animals, they failed to gain weight, were less physically active, suffered from loss of white adipose tissue, reduced muscle strength, kyphosis, alopecia, hypothermia and shortened lifespan. The Mcat-deficient phenotype is attributed primarily to reduced synthesis, in several tissues, of the octanoyl precursors required for the posttranslational lipoylation of pyruvate and α-ketoglutarate dehydrogenase complexes, resulting in diminished capacity of the citric acid cycle and disruption of energy metabolism. The presence of an alternative lipoylation pathway that utilizes exogenous free lipoate appears restricted to liver and alone is insufficient for preservation of normal energy metabolism. Thus, de novo synthesis of precursors for the protein lipoylation pathway plays a vital role in maintenance of mitochondrial function and overall vigor.

Reticulocyte parameters: markers of early response to oral treatment in children with severe iron-deficiency anemia

The aim of the present study was to determine the effects of exclusive oral iron supplementation (iron sulphate 2 mg/kg/die) in asymptomatic children with severe iron-deficiency anemia [median hemoglobin (Hb) level before treatment 6.3 g/dL; range 4.5 to 7 g/dL] and to investigate the accuracy of Hb, reticulocyte hemoglobin content (CHr), and absolute reticulocyte count (ARC) as markers for monitoring early response to treatment. The increase in ARC and CHr was statistically significant at day +3. There was a significant association between suitable logarithmic functions of the percentage increase in CHr and ARC at day +3 and the fraction of required Hb increase compared with baseline to reach the mean reference value for age and sex at day +14. If these results are confirmed in a larger population, ARC and CHr could be considered affordable and widely available markers to detect early responders to oral iron therapy, and to switch unresponsive children to parenteral iron supplementation or transfusion.

Improved flagging rates on the Sysmex XE-5000 compared with the XE-2100 reduce the number of manual film reviews and increase laboratory productivity

Hematology analyzers generate suspect flags in the presence of abnormal cells. False-positive rates for flags are high on all analyzers. Sysmex, Kobe, Japan, has developed new software for its XE-5000 with improved algorithms for flagging blast cells, abnormal lymphocytes or lymphoblasts, and atypical lymphocytes. This study evaluated the efficiency of these flags in 1,002 samples. The XE-5000 was compared with the XE-2100 (Sysmex) and microscopic examination of cell morphologic features. On the XE-2100, the blast flag demonstrated 90 false-positives, 13 true-positives, and 3 false-negatives. The values on the XE-5000 were 27 false-positives, 14 true-positives, and 2 false-negatives. The abnormal lymphocyte/lymphoblast flag was assessed with the atypical lymphocyte flag. The XE-2100 showed 114 false-positives, 23 true-positives, and 20 false-negatives, and on the XE-5000, there were 45 false-positives, 22 true-positives, and 21 false-negatives. This more specific flagging reduces the number of films that require manual review.

Iron Homeostasis and Disorders in Dogs and Cats: A Review

Iron is an essential element for nearly all living organisms and disruption of iron homeostasis can lead to a number of clinical manifestations. Iron is used in the formation of both hemoglobin and myoglobin, as well as numerous enzyme systems of the body. Disorders of iron in the body include iron deficiency anemia, anemia of inflammatory disease, and iron overload. This article reviews normal iron metabolism, disease syndromes of iron imbalance, diagnostic testing, and treatment of either iron deficiency or excess. Recent advances in diagnosing iron deficiency using reticulocyte indices are reviewed.

Pharmacodynamic analysis of stress erythropoiesis: change in erythropoietin receptor pool size following double phlebotomies in sheep

A feedback receptor regulation model was incorporated into a pharmacodynamic model to describe the stimulation of hemoglobin (Hb) production by endogenous erythropoietin (EPO). The model considers the dynamic changes that take place in the EPO receptor (EPOR) pool under phlebotomy-induced anemia. Using a (125)I-rhEPO tracer the EPO clearance changes are evaluated longitudinally prior to and following phlebotomy-induced anemia indirectly to evaluate changes in the EPOR pool size, which has been shown to be linearly related to the clearance. The proposed model simultaneously captures the general behavior of temporal changes in Hb relative to EPO plasma clearance in five lambs (r = 0.95), while accounting for the confounding variables of phlebotomy and changes in the blood volume in the growing animals. The results indicate that under anemia the EPOR pool size is up-regulated by a factor of nearly two over baseline and that the lowest and highest EPOR pool sizes differ by a factor of approximately four. The kinetic model developed and the data-driven mechanism proposed serves as a starting point for developing an optimal EPO dosing algorithm for the treatment of neonatal anemia.

Detection, evaluation, and management of iron-restricted erythropoiesis

Progress in our understanding of iron-restricted erythropoiesis has been made possible by important advances in defining the molecular mechanisms of iron homeostasis. The detection and diagnostic classification of iron-restricted erythropoiesis can be a challenging process for the clinician. Newer assays for markers of inflammation may allow more targeted management of the anemia in these conditions. The availability of new intravenous iron preparations provides new options for the treatment of iron-restricted erythropoiesis. This review summarizes recent advances regarding the detection, evaluation, and management of iron-restricted erythropoiesis.

Hemoglobin and plasma vitamin C levels in patients on peritoneal dialysis

OBJECTIVE

To determine the contribution of vitamin C (Vit C) status in relation to hemoglobin (Hb) levels in patients on long-term peritoneal dialysis (PD).

METHODS

56 stable PD patients were evaluated in a cross-sectional survey. Plasma samples were collected for Vit C (analyzed by HPLC with electrochemical detection) and high-sensitivity C-reactive protein (hs-CRP) determinations. Clinical records were reviewed for Hb, transferrin saturation (TSAT), ferritin, erythropoietin (EPO) dose, and other clinical parameters. Dietary Vit C intake was evaluated by patient survey and from patient records. Total Vit C removed during PD treatment was measured in 24-hour dialysate collections.

RESULTS

Patients showed a highly skewed distribution of plasma Vit C levels, with 40% of patients below normal plasma Vit C levels (<30 μmol/L) and 9% at higher than normal levels (>80 μmol/L). Higher plasma Vit C levels were associated with higher Hb levels (Pearson r = 0.33, p < 0.004). No direct connection between Vit C levels and reported dietary intake could be established. In stepwise multiple regression, plasma Vit C remained significantly associated with Hb (p = 0.017) but there was no significant association with other variables (dialysis vintage, age, ferritin, TSAT, hs-CRP, residual renal function, and EPO dose). In 9 patients that were evaluated for Vit C in dialysate, plasma Vit C was positively associated (Spearman r = 0.85, p = 0.01) with the amount of Vit C removed during dialysis treatment.

CONCLUSIONS

These data indicate that plasma Vit C is positively associated with higher Hb level. Vit C status could play a major role in helping PD patients to utilize iron for erythropoiesis and achieve a better Hb response during anemia management.

A pilot prospective randomized trial of postoperative epoetin alfa in patients undergoing major operation for upper gastrointestinal malignancy

INTRODUCTION

Strategies to reduce red blood transfusion utilization in cancer patients undergoing operation are needed.

HYPOTHESIS

Postoperative epoetin alfa (40,000 units subcutaneous on postoperative days 1 and 7) is associated with improved hematologic parameters in patients undergoing major abdominal surgery for malignancy.

MATERIALS AND METHODS

Prospective, blinded, randomized trial of epoetin alfa (40,000 units subcutaneous on postoperative days 1 and 7) versus placebo in patients undergoing major abdominal operation for malignancy. Primary endpoints were immature reticulocyte fraction, reticulocyte count, and hemoglobin, which were measured on postoperative days 4, 7, and between 14 and 20. Secondary endpoints were transfusions and complications in the 2 groups.

RESULTS

Forty patients were enrolled. There were no significant differences in immature reticulocyte fraction (P = 0.78), reticulocyte count (P = 0.42), or hemoglobin (0.35) in patients randomized to receive epoetin alfa versus placebo. There was no significant difference in red blood cell transfusion rate or postoperative complications in patients who received epoetin alfa compared with placebo.

DISCUSSION

The use of postoperative epoetin alfa (40,000 units subcutaneous on postoperative days 1 and 7) in patients undergoing major operation for abdominal or pelvic malignancy is not supported by this randomized trial.

Quality counts: new parameters in blood cell counting

Recently several parameters have been introduced to the complete blood count such as nucleated red blood cells, immature granulocytes; immature reticulocyte fraction, immature platelet fraction and red cell fragments as well as new parameters for detection of functional iron deficiency. Leucocyte positional parameters, which may diagnose specific diseases (e.g. differentiate between abnormal lymphocytes in leukaemia and viral conditions and may also detect malarial infection) are now available. At this time they are only used for research; however, generally such parameters later become reportable. One manufacturer's routine analyser allows measurement of cells by flow cytometry using monoclonal antibodies. Currently, there are no accredited external quality assessment schemes (EQAS) for these parameters. For a number of parameters, on some instruments, there is no internal quality control, which brings into question whether these parameters should be used for clinical decision making. Other more established parameters, such as mean platelet volume, red cell distribution width and the erythrocyte sedimentation rate do not have EQAS available. The UK National EQAS for General Haematology held a workshop earlier this year in 2008 to discuss these parameters. Participants were asked to provide a consensus opinion on which parameters are the most important for inclusion in future haematology EQAS.

Analysis of red cell parameters on the Sysmex XE 2100 and ADVIA 120 in iron deficiency and in uraemic chronic disease

OBJECTIVE

The percentage measurement of hypochromic red cells (HYPO) and reticulocyte haemoglobin content (CHr) using the ADVIA system has recently been validated as a useful tool in indicating iron deficiency, also in cases of chronic diseases such as renal failure. The aim of this study was to evaluate the extent to which the red cell parameters, RBC-Y and RET-Y, provided by Sysmex XE 2100, correlate with HYPO and CHr.

MATERIAL AND METHODS

The laboratory markers of iron status were evaluated together with HYPO, CHr, RBC-Y and RET-Y in 92 healthy subjects (C), 42 iron-deficient patients (ID) and 88 uraemic patients receiving regular dialysis treatment (RDT).

RESULTS

In ID patients, increased HYPO and decreased RBC-Y, CHr and RET-Y values, with no overlapping with reference values, were found and a significant correlation was present between ADVIA 120 and Sysmex indices (p<0.001 for each correlation). In RDT patients, HYPO median values were increased with a wide distribution of values (95 % reference range = 0.7-27.5 % and 0.7-22.6 % in men and women, respectively). In contrast, RBC-Y was normal/increased (95 % reference range = 169.4-191.1 and 168.7-190.5 in men and women, respectively), even though there was a significant correlation between them (p<0.001). CHr and RET-Y values were within the reference range; moreover, in these patients mean cell volume of red cells and of reticulocytes (MCV and MCVr) median values were increased.

CONCLUSIONS

This study confirmed the validity of RBC-Y in the management of ID, but not in RDT, where the diagnostic power of RBC-Y as an index of cell hypochromia is limited owing to high MCV values.

In-depth validation of acridine orange staining for flow cytometric parasite and reticulocyte enumeration in an experimental model using Plasmodium berghei

Flow cytometry is potentially an effective method for counting malaria parasites, but inconsistent results have hampered its routine use in rodent models. A published two-channel method using acridine orange offers clear discrimination between the infected and uninfected erythrocytes. However, preliminary studies showed concerns when dealing with Plasmodium berghei-infected blood samples with high numbers of reticulocytes. In hyperparasitemic or chronic P. berghei infection, enhanced erythropoietic activity results in high numbers of circulating immature reticulocytes. We show that even though the protocol offered good discrimination in newly infected animals, discrimination between infected erythrocytes and uninfected reticulocytes became difficult in animals with hyperparasitemia or chronic infections maintained with subcurative treatment. Discrimination was especially hampered by increased nucleic acid content in immature uninfected reticulocytes. Our data confirms that though flow cytometry is a promising analytical tool in malaria research, care should still be taken when analysing samples from anemic or chronically infected animals.

[Review of haematology and biochemistry parameters to identify iron deficiency]

INTRODUCTION

There has been a continuous improvement in the methods to detect iron deficiency, a common condition in children, in the last decades or so, but it is still difficult to establish which parameters should be included in a diagnostic panel for iron deficiency and iron deficiency anaemia. The objectives of this study were to evaluate the diagnostic efficiency of commonly used haematological and biochemical markers, as well as the reticulocyte haemoglobin content (CHr) in the diagnosis of iron deficiency with or without anaemia.

STUDY DESIGN

A descriptive cross-sectional study was carried out on an urban population of both sexes aged 6 months to 14 years. A complete blood cell count with CHr was obtained. Biochemical markers of iron metabolism, transferrin saturation, serum iron, ferritin and total iron binding capacity were also measured.

RESULTS

Samples were obtained for 237 children. A multiple stepwise logistic regression analysis identified CHr and iron serum as the only parameters independently associated to iron deficiency (P<0.05). CHr was the strongest predictor of iron deficiency and iron deficiency anaemia.

CONCLUSIONS

Our study indicates that the measurement of CHr may be a reliable method to assess deficiencies in tissue iron supply. CHr together with a complete blood count may provide an alternative to the traditional biochemical panel for the diagnosis of iron deficiency in children.

Modeling time variant distributions of cellular lifespans: increases in circulating reticulocyte lifespans following double phlebotomies in sheep

Many pharmacodynamic (PD) models of cellular response assume a single and time invariant lifespan of all cells, despite the existence of a true underlying distribution of cellular lifespans and known changes in the lifespan distributions with time. To account for these features of cellular populations, a time variant cellular lifespan distribution PD model was formulated and theoretical aspects of modeling cellular populations presented. The model extends prior work assuming time variant "point distributions" of cellular lifespans (Freise et al. J Pharmacokinet Pharmacodyn 34:519-547, 2007) and models assuming a time invariant lifespan distribution (Krzyzanski et al. J Pharmacokinet Pharmacodyn 33:125-166, 2006). The formulated time variant lifespan distribution model was fitted to endogenous plasma erythropoietin (EPO), reticulocyte, and red blood cell (RBC) concentrations in sheep phlebotomized on two occasions, 8 days apart. The time variant circulating reticulocyte lifespan was modeled as a truncated and scaled Weibull distribution, with the location parameter of the distribution non-parametrically represented by an end constrained quadratic spline function. The formulated time variant lifespan distribution model was compared to the identical time invariant distribution, time variant "point distribution", and time invariant "point distribution" cellular lifespan models. Parameters of the time variant lifespan distribution model were well estimated with low standard errors. The mean circulating reticulocyte lifespan was estimated at 0.304 days, which rapidly increased over 3-fold following the first phlebotomy to a maximum of 1.03 days (P = 0.009). On average, the percentage of erythrocytes being released as reticulocytes maximally increased an estimated two-fold following the phlebotomies. The primary features of immature RBC physiology were captured by the model and gave results consistent with other estimates in sheep and humans. The comparison of the four lifespan models gave similar parameter estimates of the stimulation function and fits to the RBC data. However, the time invariant models fit the reticulocyte data poorly, while the time variant "point distribution" cellular lifespan model gave physiologically unrealistic estimates of the changes in the circulating reticulocyte lifespan under stress erythropoiesis. Thus the underlying physiology must be considered when selecting the most appropriate cellular lifespan model and not just the goodness-of-fit criteria. The proposed PD model and the numerical implementation allows for a flexible framework to incorporate time variant lifespan distributions when modeling populations of cells whose production or stimulation depends on endogenous growth factors and/or exogenous drugs.

[Clinical significance of reticulocyte maturation parameters in the differential diagnosis of macrocytic anemias]

BACKGROUND

Macrocytic anemias are commonly seen in clinical practice, and precise etiologic diagnosis is essential for proper management. We evaluated the clinical utility of reticulocyte maturation parameters in macrocytic anemias to discriminate among myelodysplastic syndrome (MDS), megaloblastic anemia (MA), and non-megaloblastic macrocytic anemia associated with chronic liver disease (MA-CLD).

METHODS

Using an automated reticulocyte counter, we retrospectively analyzed and compared reticulocyte maturation parameters including immature reticulocyte fraction (IRF), mean reticulocyte volume (MRV), mean sphered cell volume (MSCV) of normal control (N=34), and patients diagnosed with MDS (N=31), MA (N=52), and MA-CLD (N=196).

RESULTS

Macrocytic anemias from MA, MDS and MA-CLD showed higher values of reticulocyte maturation parameters including IRF, MRV and MSCV than normal control (P<0.01). MDS showed higher values of reticulocyte maturation parameters including IRF, MRV and MSCV than MA-CLD (P<0.01). IRF and MRV were significantly lower in MA-CLD than in both MA and MDS (P<0.01). MSCV was significantly higher in MDS than in MA (P<0.01).

CONCLUSIONS

This study indicates that the measurement of reticulocyte maturation parameters may be a useful tool in the differential diagnosis of macrocytic anemia. The presence of high values of IRF (> or = 0.39), MRV (> or = 129.5 fL), and MSCV (> or = 102.3 fL) makes the diagnosis of MA-CLD unlikely and underlying MDS should be considered.

Effect of hydroxyurea on immature reticulocyte fraction in sickle cell anemia

Immature reticulocyte fraction (IRF) is a good indicator of bone marrow erythropoiesis in response to hemolysis or tissue hypoxia and is markedly increased in sickle cell disease (SS). We compared IRF changes in SS patients with those who were treated with hydroxyurea (SS-HU), and those who had concurrent alpha globin gene deletion (SS-(- deletion). Forty-two patients including 16 SS, 16 SS-HU, and 10 SS-alpha-deletion patients were studied. Significant decreases (P <.01) in reticulocyte indices including IRF, the reticulocyte percentage, and absolute reticulocyte count (ARC) were observed in SS-alpha-deletion compared to SS patients. On the other hand, although the reticulocyte percentage (P <.01) and ARC (P <.01) were significantly decreased in SS-HU compared with SS patients, the IRF was persistently elevated in both groups (P = .4), suggesting continuous bone marrow stimulation in SS-HU patients in response to tissue hypoxia. The possible underlying physiological mechanisms are discussed.

Evaluation of reticulocyte parameters in iron deficiency, vitamin B(12) deficiency and beta-thalassemia minor patients

The aim of this study was to test the clinical utility of reticulocyte parameters in differential diagnosis in iron deficiency anemia (IDA), vitamin B(12) deficiency (B12) and beta-thalassemia minor (TM). We analyzed the percentage of reticulocyte, absolute reticulocyte count, mean content hemoglobin of reticulocyte (CHr), mean corpuscular volume of reticulocyte (MCVr), corpuscular hemoglobin concentration mean of reticulocyte (CHCMr), MCVr/MCV ratio, CHr/CH ratio and CHCMr/CHCM ratio in healthy donors (n = 34), iron deficiency (IDA) (n = 41), vitamin B(12) deficiency (B12) (n = 22), and TM (n = 34). This study demonstrates that the cutoff value of CHr was 25.7 as indicative of IDA (85.4% sensitivity, 97.1% specificity). CHr and MCVr may be useful for TM (cutoff value < or = 24.8 for CHr) and B12 (>102.1, cutoff value for MCVr), respectively. Sensitivity and specificity of these parameters were 90.9, 86.4% and 97.1, 82.4%, respectively. CHCMr is useful to differentiate IDA and TM from B12. While CHr was low value in microcytic groups (mean 21.8 +/- 3.3 for IDA, 21.0 +/- 2.9 for TM), it was high in B12 (mean 32.1 +/- 5.7). However, that of CHr/CH ratio was only significantly in IDA group compared with the control (P < 0.05, mean 0.98). Therefore, there are limitations regarding CHr and CHr/CH ratio differential diagnosis in microcytic and macrocytic groups. CHr, MCVr, and CHCMr are not sufficiently sensitive and specific to differentiate TM from IDA. We conclude that measurement of reticulocyte count and parameters may be a very useful implement in the diagnosis of IDA and TM.

Pharmacodynamic analysis of time-variant cellular disposition: reticulocyte disposition changes in phlebotomized sheep

Most pharmacodynamic (PD) models of cellular response assume a time-invariant (i.e., constant) cellular disposition despite known changes in the disposition with time, such as the reticulocyte residence time in the systemic circulation during stress erythropoiesis. To account for changes in cellular disposition, a comprehensive PD model that involves endogenous erythropoietin (Epo), reticulocytes, and hemoglobin responses was developed in phlebotomized sheep that considers a time-variant reticulocyte residence time and allows for the simultaneous determination of changes in the cellular disposition and cellular production. Five sheep were phlebotomized to hemoglobin concentrations of approximately 4 g/dl. Epo concentrations, reticulocytes, and hemoglobin concentrations were frequently sampled for 5-7 days prior to and 25-30 days following the phlebotomy. Initial steady-state conditions were assumed and the time-variant reticulocyte residence time in the systemic circulation was semiparametrically represented using a constrained spline function. Hemoglobin production was modeled using a Hill function via an effect site compartment. The initial steady state reticulocyte residence time in the systemic circulation was estimated as 0.477 (0.100) (mean (SD)) days, which maximally increased 2.01- to 2.64-fold higher than the initial steady-state residence time 5.95 (0.899) days post-phlebotomy (P < 0.01). On average, the residence time returned to steady-state values 15.4 (2.36) days post-phlebotomy, which was not significantly different from the initial steady-state value (P > 0.05). The baseline hemoglobin production rate was estimated at 0.0929 (0.0472) g/kg/day and the maximum production rate under stress phlebotomy was estimated at 0.504 (0.0422) g/kg/day. These data indicate that endogenously released Epo under acute anemic conditions can increase hemoglobin production approximately 5-fold. The determined increase in reticulocyte residence time produced under stress erythropoiesis is similar to the commonly reported 2- to 3-fold increase observed in human patients.

Increased erythropoietin elimination in fetal sheep following chronic phlebotomy

PURPOSE

To determine by pharmacokinetic (PK) means the role of erythropoietin-receptor (EPO-R) upregulation in fetuses on the elimination of erythropoietin (EPO).

MATERIALS AND METHODS

Six fetal sheep were catheterized at a gestational age of 125-127 days and phlebotomized daily for 6 days. Paired tracer PK studies using recombinant human EPO (rHuEPO) were conducted in the sheep fetuses at baseline and post-phlebotomy, 7 days later. A PK model with Michaelis-Menten elimination was simultaneously fit to the PK data at baseline and post-phlebotomy for each fetus.

RESULTS

Daily phlebotomies reduced the hemoglobin levels from baseline values of 10.8 (5%) (mean (C.V.)) g/dl to a nadir of 4.5 (17%) g/dl post-phlebotomy. The endogenous EPO concentration rapidly increased after the first phlebotomy and remained elevated, although variable, thereafter. The Michaelis-Menten maximal rHuEPO elimination rate parameter, V(max), was significantly greater post-phlebotomy than at baseline (p < 0.05), increasing 1.31 fold. The fetal baseline "linear" clearance at very low concentrations of rHuEPO was determined to be 117 ml/kg/h, similar to that determined in newborn sheep but 2-3 fold higher than that determined in adult sheep.

CONCLUSIONS

The observed increase in V(max) is consistent with an up-regulation of EPO-R due to a positive feedback resulting from the phlebotomy-induced anemia.

Urea stimulation of KCl cotransport induces abnormal volume reduction in sickle reticulocytes

KCl cotransport (KCC) activity contributes to pathologic dehydration in sickle (SS) red blood cells (RBCs). KCC activation by urea was measured in SS and normal (AA) RBCs as Cl-dependent Rb influx. KCC-mediated volume reduction was assessed by measuring reticulocyte cellular hemoglobin concentration (CHC) cytometrically. Urea activated KCC fluxes in fresh RBCs to levels seen in swollen cells, although SS RBCs required lower urea concentrations than did normal (AA) RBCs. Little additional KCC stimulation by urea occurred in swollen AA or SS RBCs. The pH dependence of KCC in "euvolemic" SS RBCs treated with urea was similar to that in swollen cells. Urea triggered volume reduction in SS and AA reticulocytes, establishing a higher CHC. Volume reduction was Cl dependent and was limited by the KCC inhibitor, dihydro-indenyl-oxyalkanoic acid. Final CHC depended on urea concentration, but not on initial CHC. Under all activation conditions, volume reduction was exaggerated in SS reticulocytes and produced higher CHCs than in AA reticulocytes. The sulfhydryl-reducing agent, dithiothreitol, normalized the sensitivity of KCC activation to urea in SS RBCs and mitigated the urea-stimulated volume decrease in SS reticulocytes, suggesting that the dysfunctional activity of KCC in SS RBCs was due in part to reversible sulfhydryl oxidation.

Stability of blood cell counts, hematologic parameters and reticulocytes indexes on the Advia A120 hematologic analyzer

Delayed sample analysis is not a rare circumstance in clinical and laboratory practice, especially when blood samples are shipped to distant centralized laboratories, when the analysis can not be readily performed, or when retesting is appropriate. In this study we sought to evaluate the stability of conventional and new hematologic parameters in blood specimens stored for as long as 24 hours at 4 degrees C. Of the 21 hematologic parameters tested with the use of the Advia 120 hematologic analyzer (Bayer Diagnostics), means for paired samples of specimens differed significantly over the 24-hour storage period for hematocrit, main corpuscular volume, percentage of macrocytes, platelet count, main platelet volume, reticulocyte count and percentage, and reticulocyte hemoglobin content (all P < .01). We noted no significant changes in the other parameters tested or in the white blood cell differential. The overall distribution of the immature reticulocytes fractions remained substantially unchanged, though the high staining-intensity fraction showed a considerable shift from the baseline measure. Bland-Altman plots and limits-of-agreement analysis showed mean biases between -4.8% and 37.2% and relative coefficients of variations ranging from 0.4% to 32.7%. The 95% agreement interval in the set of differences was satisfactory and almost within the current analytic-quality specifications for desirable bias. The results of this investigation suggest that, within certain limitations for parameters derived or calculated from cellular volumes, blood specimens stored for as long as 24 hours at 4 degrees C may be suitable for hematologic testing.

Single-dose darbepoetin administration to anemic preterm neonates

OBJECTIVE

Darbepoetin is longer acting and more potent than recombinant erythropoietin (rEpo). In certain situations, preterm neonates might benefit from rEpo, and for such patients darbepoetin would require fewer doses at a lower cost. However, the proper dose and dosing interval have not been established.

STUDY DESIGN

We performed a prospective trial in two level III Neonatal Intensive Care Units. Patients <32 weeks gestation at birth, with a birth weight (BW) <1500 g, were eligible for participation if they were >21-days-old and had a hemoglobin (Hgb) concentration </or=10.5 g/dl. In all, 12 were to receive a single subcutaneous (s.c.) dose at either 1 or 4 microg/kg. Once before the dose was given, and at two preset intervals after, blood was obtained for immature reticulocyte fraction (IRF) and absolute reticulocyte count (ARC). Once before and at four preset intervals after, blood was obtained for pharmacokinetic studies.

RESULTS

The 12 subjects had BWs of 1129+/-245 g (mean+/-SD), were 29.2+/-1.2 weeks gestation at delivery, and were 43+/-12 days old with an Hgb concentration of 9.6+/-1.0 g/dl when the darbepoetin was given. Six received 1 microg/kg and six 4 microg/kg. The IRF increased (p<0.05) as did the ARC (p<0.05). The increases in IRF were somewhat greater among the 4 microg/kg recipients (P=0.06). The highest recorded concentrations of drug occurred 6 to 12 hours after administration. The combined 6 and 12 hours values were 185+/-106 mU/ml in the 1 microg/kg group vs 597+/-238 in the 4 microg/kg group (p<0.002). The t(1/2) was 26 hours (range 10 to 50). The biovailability-normalized clearance was 19 ml/hour/kg (range 5 to 54).

CONCLUSIONS

A single s.c. dose of darbepoetin given to preterm neonates accelerated effective erythropoiesis. The pharmacodynamic and pharmacokinetic findings suggest that darbepoetin dosing in neonates would require a higher unit dose/kg and a shorter dosing interval than are generally used for anemic adults.

Pharmacodynamic Analysis of Changes in Reticulocyte Subtype Distribution in Phlebotomy-Induced Stress Erythropoiesis

Changes in the reticulocyte subtype distribution (high, medium and low reticulocytes count (HR, MR, LR)) measured by flow cytometry following phlebotomy-induced stress erythropoiesis (abruptly dropping hemoglobin to 3-4 g/dl over 4-5 hr) and the pharmacodynamic (PD) relationship to the stimulated erythropoietin (EPO) was investigated in sheep. A PD model was developed that describes the relationship between EPO and the reticulocyte maturity distribution fractions (r=0.95+/-0.02, mean +/- SD). The lag-time between EPO activation of erythroid progenitor cells and the subsequent increase in the least mature HR fraction in the peripheral circulation was 0.72 +/- 0.08 days. The mean transition times (in days) for all three reticulocyte fractions changed at baseline from, T(HR) : 0.09 +/- 0.06, T(MR) : 0.06 +/- 0.04, and T(LR) : 0.46 +/- 0.24 to T(HR) : 0.13 +/- 0.08, T(MR) : 0.29 +/- 0.15, and T(LR) : 2.3 +/- 0.24 under stress erythropoiesis. The total mean residence time for a reticulocyte in the peripheral circulation, T(total) (T(HR) + T(MR) + T(LR)), increased from 0.60 +/- 0.33 days under basal to 2.8 +/- 0.09 days during stress erythropoiesis. The statistically significant increase observed for T(LR) and T(total) supports the hypothesis that stress erythropoiesis perturbs the mean reticulocyte transition times. A correlation analysis between various new, proposed metrics involving the HR, MR and LR fractions and the total reticulocyte count, with the latter indicative of stress erythropoiesis at higher total counts, revealed a highly significant correlation indicating these new metrics may be a valuable adjunct to the reticulocyte maturation index (RMI) and the immature reticulocyte fractions index (IRF) previously used in assessing erythropoietic activity in response to anemia.

Delta-CHr improves the identification of anemic syndromes and the evaluation of hemoglobin synthesis

Reticulocyte hemoglobin content (CHr) is considered an index of iron status, helpful in the differential diagnosis of microcytoses. Its potential can be enhanced by comparing CHr dynamic reference values (CHr-e: expected CHr), which are proportional to the MCVr variations occurring in micro- or macrocytosis, with measured CHr values. We demonstrate that the difference between measured CHr and CHr-e (DeltaCHr) is helpful to differentiate the anemic syndromes and, in particular, beta-thalassemia vs. presumable sideropenia. DeltaCHr can also indicate when to interrupt iron supplementation. DeltaCHr allows an insight into the erythropoiesis of thalassemic and sideropenic subjects, pointing out the reduced hemoglobin production and ineffective erythroid activity in these conditions.

An algorithm using reticulocyte hemoglobin content (CHr) measurement in screening adolescents for iron deficiency

PURPOSE

To evaluate whether the use of an algorithm including reticulocyte hemoglobin content (CHr), a new hematologic parameter, in addition to the screening complete blood count (CBC), improves detection of iron deficiency and iron deficiency anemia in healthy adolescents.

METHODS

After initiation of an algorithm using CHr in addition to CBC results for identifying iron-deficient patients in a primary care hospital-based adolescent clinic, we reviewed results of all hematological tests performed in the clinic during an 8-month period. Electronic medical records were screened for health status and inclusion criteria. We determined the number of patients with low hematocrit values, low mean cell volume (MCV), and low CHr. To evaluate the impact of the protocol, we calculated the percentage of cases in which the CHr results suggested a management plan different from that which would have been formulated using the CBC results only.

RESULTS

A total of 381 patients (mean age 16.8 +/- 3.1 years) were included in the study. Anemia was diagnosed by the Centers for Disease Control (CDC) guidelines in 63 patients (16.5%), low MCV in 170 patients (44.6%), and a low CHr in 80 (21%) patients. In 68% of anemia cases, a normal CHr suggested that iron deficiency was not the cause of the anemia. Although low MCV values were found in 38 (60.4%) of all anemic cases, mean MCV was significantly (p < 0.001) lower in the 19 cases with a low CHr as well. In 19% of 318 patients with a normal hematocrit (HCT), a low CHr suggested the need for treatment of early iron deficiency. In 103 (27%) cases, CHr suggested a different treatment plan from that which would have been formulated using the screening CBC only.

CONCLUSIONS

The use of an algorithm including CHr to screen for iron deficiency anemia may increase the accuracy of diagnosis, enabling early detection and treatment of iron deficiency in adolescents without the need for additional costly iron studies.

Performance evaluation of the ADVIA 2120 hematology analyzer: an international multicenter clinical trial

Automated cell counters are widely used in modern clinical laboratories to provide reliable, fast, and cost-effective complete blood counts (CBCs), white blood cell differentials, and reticulocyte measurements. In addition, some advanced instruments provide novel parameters, such as the hemoglobin content of reticulocytes or the percentage of hypochromic cells, and are capable of analysis of a variety of body fluids. Bayer recently introduced the ADVIA 2120 system as an automation-ready cell counter for mid- to high-volume testing in the clinical laboratory. This instrument, which builds on the established technology of the ADVIA 120 system, operates with a cyanide-free method for hemoglobin measurement, has a new user interface, and can routinely analyze biological fluid samples in addition to blood. We used 749 samples from 6 worldwide trial sites to evaluate the clinical performance of this new device. Accuracy of the ADVIA 2120 system versus its predecessor model, the ADVIA 120 system, was excellent for all CBC and white cell differential parameters and reticulocyte counts (all correlation coefficients except for basophils >0.9). Correlation of the white cell differential with the standard manual method and within-run precision of the ADVIA 2120 system also was very good. Use of the novel cyanide-free method for hemoglobin measurement had no clinically significant impact on hemoglobin results, even in patients with hemoglobinopathies. We concluded that the ADVIA 2120 system has clinically equivalent performance to the ADVIA 120 system.

Proficiency testing of reticulocyte counting in Ontario

The reticulocyte count reflects the erythropoietic activity of the bone marrow and is thus useful in both the approach to the diagnosis of anemia and in monitoring bone marrow response to therapy. Traditionally, reticulocyte quantitation relied upon microscopic techniques; recently automated reticulocyte quantitation has become widely available. External quality assessment (EQA) of reticulocyte quantitation has not been widely reported; this paper presents data from reticulocyte EQA surveys conducted in Ontario between November 2000 and October 2004. Samples with normal and increased reticulocyte levels were obtained from adult donors and analyzed within 48 hours. We found that despite improved accuracy and precision, automated reticulocyte counting techniques do not translate into markedly improved inter-laboratory accuracy and precision. Further, we found that both microscopic and automated techniques can effectively differentiate between patients with normal and those with increased reticulocyte counts. Finally, we ascertained that reference intervals submitted with the initial surveys revealed that laboratories could have made erroneous clinical interpretations of their normal or elevated reticulocyte counts. The reestablishment of reference intervals by participants resulted in a marked improvement of the reference intervals submitted on subsequent surveys.

The ADVIA 2120 hematology system: flow cytometry-based analysis of blood and body fluids in the routine hematology laboratory

The ADVIA 2120 Hematology System was recently released by Bayer HealthCare, Diagnostics Division, as a bench-top analyzer designed for medium- to large-volume laboratories. This flow cytometry-based system uses light scatter, differential white blood cell (WBC) lysis, and myeloperoxidase and oxazine 750 staining to provide a complete blood cell count, a WBC differential, and a reticulocyte count. A cyanide-free method is used to measure hemoglobin colorimetrically. The system is automation ready; in addition to its capability for analyzing peripheral blood specimens, the analyzer is also equipped to analyze cerebrospinal fluid samples. In this article we explain the underlying technology of the ADVIA 2120, provide linearity ranges, method-specific reference ranges, and stability data, and describe novel parameters and applications that are unique to the methodology used by this instrument. Finally, we discuss research applications and future directions, such as the use of this hematology analyzer in the determination of fetal lung maturity.

Rapid identification of iron deficiency in blood donors with red cell indexes provided by Advia 120

BACKGROUND

A new generation of automated hematology analyzers allows the rapid determination of various red cell (RBC) indexes, including the percentage of hypochromic mature RBCs (HYPOm) and the hemoglobin (Hb) content of reticulocytes (CHr). These indexes have not yet been validated as measures for the detection of iron deficiency in blood donors.

STUDY DESIGN AND METHODS

Iron status was evaluated in a total of 1142 unselected prospective blood donors based on measurement of serum ferritin, soluble transferrin receptor, and Hb compared to RBC indexes provided by an automated hematology analyzer (Advia 120, Bayer HealthCare) including HYPOm and CHr.

RESULTS

Assuming that the most precise measure for body iron storage is related to the logarithm of the ratio of soluble transferrin receptor to ferritin, the sensitivity of ferritin for the diagnosis of iron depletion was 89 percent compared to 57 percent for HYPOm and CHr, respectively, to 69 percent for the combination of both RBC indexes, and to 26 percent for Hb concentration.

CONCLUSION

The RBC indexes HYPOm und CHr are significantly better screening measures for identification of iron depletion in blood donors than Hb.