Protocol for evaluation of automated blood cell counters. International Committee for Standardization in Haematology (ICSH)

Effects of Using Different Indirect Techniques on the Calculation of Reference Intervals: Observational Study

BACKGROUND

Reference intervals (RIs) play an important role in clinical decision-making. However, due to the time, labor, and financial costs involved in establishing RIs using direct means, the use of indirect methods, based on big data previously obtained from clinical laboratories, is getting increasing attention. Different indirect techniques combined with different data transformation methods and outlier removal might cause differences in the calculation of RIs. However, there are few systematic evaluations of this.

OBJECTIVE

This study used data derived from direct methods as reference standards and evaluated the accuracy of combinations of different data transformation, outlier removal, and indirect techniques in establishing complete blood count (CBC) RIs for large-scale data.

METHODS

The CBC data of populations aged ≥18 years undergoing physical examination from January 2010 to December 2011 were retrieved from the First Affiliated Hospital of China Medical University in northern China. After exclusion of repeated individuals, we performed parametric, nonparametric, Hoffmann, Bhattacharya, and truncation points and Kolmogorov-Smirnov distance (kosmic) indirect methods, combined with log or BoxCox transformation, and Reed-Dixon, Tukey, and iterative mean (3SD) outlier removal methods in order to derive the RIs of 8 CBC parameters and compared the results with those directly and previously established. Furthermore, bias ratios (BRs) were calculated to assess which combination of indirect technique, data transformation pattern, and outlier removal method is preferrable.

RESULTS

Raw data showed that the degrees of skewness of the white blood cell (WBC) count, platelet (PLT) count, mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and mean corpuscular volume (MCV) were much more obvious than those of other CBC parameters. After log or BoxCox transformation combined with Tukey or iterative mean (3SD) processing, the distribution types of these data were close to Gaussian distribution. Tukey-based outlier removal yielded the maximum number of outliers. The lower-limit bias of WBC (male), PLT (male), hemoglobin (HGB; male), MCH (male/female), and MCV (female) was greater than that of the corresponding upper limit for more than half of 30 indirect methods. Computational indirect choices of CBC parameters for males and females were inconsistent. The RIs of MCHC established by the direct method for females were narrow. For this, the kosmic method was markedly superior, which contrasted with the RI calculation of CBC parameters with high |BR| qualification rates for males. Among the top 10 methodologies for the WBC count, PLT count, HGB, MCV, and MCHC with a high-BR qualification rate among males, the Bhattacharya, Hoffmann, and parametric methods were superior to the other 2 indirect methods.

CONCLUSIONS

Compared to results derived by the direct method, outlier removal methods and indirect techniques markedly influence the final RIs, whereas data transformation has negligible effects, except for obviously skewed data. Specifically, the outlier removal efficiency of Tukey and iterative mean (3SD) methods is almost equivalent. Furthermore, the choice of indirect techniques depends more on the characteristics of the studied analyte itself. This study provides scientific evidence for clinical laboratories to use their previous data sets to establish RIs.

Assessment of serum vitamin D levels in Egyptian children with beta-thalassemia major

Background

Beta-thalassemia major patients are at increased risk of complications including endocrinopathies and bone disease due to iron overload. So, this study aimed to assess the growth parameters, serum levels of 25-OH-vitamin D, calcium, and phosphorous in children with beta-thalassemia major. This was a case-control study that included 55 children with beta-thalassemia major compared with 30 sex- and age-matched healthy children that served as a control group. All enrolled children were subjected to full history taking, clinical examination including anthropometric measurements, and laboratory investigations including complete blood count, serum ferritin, levels of serum calcium, phosphorus, and 25-OH-vitamin D.

Results

Body mass index was statistically significantly lower in the thalassemic group (P < 0.001). It was observed that vitamin D levels were significantly lower in thalassemic patients than in controls (P value < .0001). The mean serum 25-OH-vitamin D levels were 19.84 ± 5.79 ng/ml and 44.98 ± 5.77 ng/ml, respectively; 22 cases (40%) had insufficient vitamin D, and 5 cases (9%) had deficient vitamin D. Regarding serum calcium and phosphorous, there was no significant difference between the thalassemic and control groups.

Conclusion

Children with beta-thalassemia major had low body mass index and metabolic abnormality in the form of lower serum levels of vitamin D that signify the importance of therapeutic interventions.

Early Predictors of Renal Dysfunction in Pediatric Patients with Sickle Cell Disease

Sickle cell disease (SCD) is a hereditary hemoglobinopathy characterized by abnormal hemoglobin production which leads to hemolytic anemia and intermittent occlusion of small blood vessels, which further leads to tissue ischemia, chronic organ damage, and organ dysfunction including urinary system. To measure the serum levels of cystatin-C and beta 2 microglobulin in pediatric patients with SCDand to investigate their significance as early biomarkers of glomerular and/or renal tubular dysfunction. This study was conducted among 70 children with SCD and 40 age and sex-matched children as a control group. All subjects underwent a full medical history, through physical examination, laboratory investigations including blood urea, serum creatinine, serum ferritin, estimated glomerular filtration rate (eGFR) using the Schwartz formula, creatinine clearance, urinary albumin/creatinine ratio, serum cystatin-C, and β-2 microglobulin levels. Pediatric patients with SCD had significantly higher serum cystatin-C and β-2 microglobulin levels compared to controls. In addition, serum cystatin-C and β-2 microglobulin levels were positively correlated with blood urea, serum creatinine, serum ferritin, urinary albumin/creatinine ratio, duration of iron chelating agents and frequency of blood transfusion/year. Serum cystatin-C and β-2 microglobulin levels were negatively correlated with hemoglobin. Our data concluded that serum cystatin-C and β-2 microglobulin had highersensitivity and specificity (91%, 90% and 85.7%, 100%, respectively) than serum creatinine (79% and85%, respectively). Serum Cystatin-C and β-2 microglobulin are early specific and sensitive biomarkers for evaluating glomerular and tubular dysfunction in children with SCD.

Role of serum cystatin-C and beta-2 microglobulin as early markers of renal dysfunction in children with beta thalassemia major

BACKGROUND

Although advancements have been made in the management of thalassemic patients, many unrecognized complications have emerged, such as renal abnormalities.

AIM

To measure serum levels of cystatin-C and β-2 microglobulin in children with beta-thalassemia major (β-TM) and investigate their significance as early markers of glomerular and tubular dysfunctions.

SUBJECTS AND METHODS

The study was performed on 70 children with (β-TM) and 20 apparently healthy children matched for age and sex as a control group. For all the enrolled children, a comprehensive medical history was obtained and complete physical examination was performed, blood urea, serum creatinine, serum ferritin, estimated glomerular filtration rate (eGFR) by Schwartz formula and creatinine clearance, albumin/creatinine ratio in urine, serum cystatin-C levels and β-2 microglobulin were measured.

RESULTS

Thalassemic children had significantly higher cystatin-C and β-2 microglobulin levels compared with control. In addition, serum cystatin-C and β-2 microglobulin were positively correlated with urea, creatinine, serum ferritin, albumin/creatinine ratio, duration of chelation therapy and frequency of blood transfusion/year and negatively correlated with creatinine clearance, hemoglobin, and eGFR. Our data demonstrated that cystatin-C and β-2 microglobulin had higher sensitivity and specificity (91.4%, 90.0%, and 85.7%, 100%, respectively) than serum creatinine and creatinine clearance (83.0%, 100% and 81.4%, 100%, respectively) for small changes in GFR.

CONCLUSION

Cystatin-C and β-2 microglobulin are specific and sensitive early biomarkers for monitoring glomerular and tubular dysfunction in children with β-TM.

Establishment of complete blood count reference intervals for Chinese preschoolers

BACKGROUND

Reference intervals are critical for interpreting test results of a clinical laboratory. The aim of this study was to establish local reference intervals of complete blood count for healthy preschoolers in China.

METHODS

Three thousand eight hundred and twenty-one blood specimens from children aged 4 months to 6 years were collected and analyzed. Complete blood counts were determined by Sysmex XT-4000i Automated Hematology Analyzer. The nonparametric 2.5th to 97.5th percentile reference ranges were calculated according to CLSI EP28-A3c guideline.

RESULTS

Reference intervals for each blood cell parameter are determinded as follows: total WBC 4.86-12.1×10⁹ /L for males and 4.73-12.3×10⁹ /L for females; RBC 4.13-5.32×10¹² /L for males and 4.08-5.24×10¹² /L for females; HGB 109-145 g/L for males and 111-143 g/L for females; HCT 33.1-41.2% for males and 33.3-41.1% for females; MCH 23.5-29.7 pg for males and 24.6-30.0 pg for females; MCHC 320-365 g/L for males and 321-362 g/L for females; MCV 71.4-85.1 fL for males and 73.8-86.9 fL for females; RDW-SD 33.5-41.9 fL for males and 33.5-41.0 fL for females; RDW-CV 12.0-15.2% for males and 11.8-14.5% for females; PLT 181-475×10⁹ /L for males and 179-456×10⁹ /L for females; PCT 0.18-0.44% for males and 0.18-0.43% for females; MPV 8.20-11.6 fL for males and 8.20-11.5 fL for females; PDW 8.40-14.4 fL for males and 8.40-14.0 fL for females; P-LCR 12.0-36.6% for males and 11.8-35.6% for females.

CONCLUSIONS

We established local complete blood count reference intervals for apparent healthy preschoolers in China. It is necessary to establishing region-specific reference intervals of complete blood count for preschoolers.

Evaluation of the immature platelet fraction as an indicator of platelet recovery in dengue patients

INTRODUCTION

Thrombocytopenia is a common complication in many disorders (such as aplastic anemia, ITP, dengue fever,), the etiology being multifactorial. Immature platelet fraction (IPF) is a new parameter which is a measure of reticulated platelets that reflects the rate of thrombopoiesis. We tried to evaluate IPF as an indicator to predict the recovery of platelets in patients with dengue.

METHODS

A total of 32 patients suffering from dengue fever (as confirmed by NS1 antigen or IgM antibody positivity for dengue) were taken for the study. The platelet count and IPF value of all these patients were evaluated on a daily basis.

RESULTS

It was found out that IPF has a strong correlation with the recovery of platelet counts in patients with dengue. 84.3% patients showed recovery within 24 h after attaining the peak IPF, 93.75% of the patients showed recovery within 24-48 h of the rise of the IPF compared with the previous day's value, and 100% patients showed a recovery within 24 h of the fall of the IPF compared with the previous days. It was also observed that 93.75% of the patients show platelet recovery within 24-48 h if the IPF was more than 10%.

CONCLUSION

Based on our study, we concluded that IPF can be used to evaluate the recovery of platelets in patients with dengue. It holds a great promise of becoming a reliable future guide for decisions concerning platelet transfusions.

Complete blood count reference intervals for healthy Han Chinese adults

BACKGROUND

Complete blood count (CBC) reference intervals are important to diagnose diseases, screen blood donors, and assess overall health. However, current reference intervals established by older instruments and technologies and those from American and European populations are not suitable for Chinese samples due to ethnic, dietary, and lifestyle differences. The aim of this multicenter collaborative study was to establish CBC reference intervals for healthy Han Chinese adults.

METHODS

A total of 4,642 healthy individuals (2,136 males and 2,506 females) were recruited from six clinical centers in China (Shenyang, Beijing, Shanghai, Guangzhou, Chengdu, and Xi'an). Blood samples collected in K2EDTA anticoagulant tubes were analyzed. Analysis of variance was performed to determine differences in consensus intervals according to the use of data from the combined sample and selected samples.

RESULTS

Median and mean platelet counts from the Chengdu center were significantly lower than those from other centers. Red blood cell count (RBC), hemoglobin (HGB), and hematocrit (HCT) values were higher in males than in females at all ages. Other CBC parameters showed no significant instrument-, region-, age-, or sex-dependent difference. Thalassemia carriers were found to affect the lower or upper limit of different RBC profiles.

CONCLUSION

We were able to establish consensus intervals for CBC parameters in healthy Han Chinese adults. RBC, HGB, and HCT intervals were established for each sex. The reference interval for platelets for the Chengdu center should be established independently.

Effect of the addition of the antioxidant taurine on the complete blood count of whole blood stored at room temperature and at 4ºC for up to 7 days

Background

The complete blood count is one of the most common routine tests. This study aimed to evaluate possible effects of the antioxidant taurine on the complete blood count of whole blood stored at room temperature and at 4ºC over seven days.

Methods

Venous blood samples of 25 healthy males were distributed into two sets of tubes with each set of four tubes containing 50 µL of solutions with zero, 2.5 g/L, 5 g/L, 10 g/L taurine. The tubes were kept at room temperature or at 4ºC. Complete blood counts were performed on seven successive days. The mean percentage changes [Δ = (mean value - mean baseline value) / mean baseline value x 100] were calculated and compared.

Results

Complete blood count parameters exhibited different patterns of behavior which were affected by the storage temperature, time and taurine concentration. Taurine at room temperature significantly enhanced the stability of: the platelet count over seven days (Δ7 at 2.5, 5 and 10 g/L taurine were 5.45, 6.11, and 5.80 x 10⁹ cells/L, respectively); the red blood cell count over five days (Δ5 at 2.5, 5 and 10 g/L taurine were 1.59, 2.79, and 1.98 x 10¹² cells/L, respectively); mean corpuscular hemoglobin over five days (Δ5 at 2.5, 5 and 10 g/L taurine were -0.91,-1.52 and -0.84 fl respectively); and red cell distribution width over two days (Δ2 at 2.5, 5 and 10 g/L taurine were 0.90%, 1.30% and -0.1%, respectively). No additional stabilizing effects of taurine were reported for the mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, hematocrit and hemoglobin, while it negatively affected the white blood cell stability.

Conclusion

Complete blood count parameters exhibited variable stability patterns in respect to temperature, time and taurine concentration.

The effect of storage on the clinical utility of the immature platelet fraction

The immature platelet fraction (%IPF) is a highly utilised new parameter in the full blood count (FBC) profile. It is a measure of the number of reticulated platelets and hence provides information on platelet transfusion requirements. It is common practice to measure %IPF values on blood samples that are several hours old, however unlike the well known good stability of other well established and more traditional FBC parameters such as haemoglobin and platelet counts, previous animal studies have shown that reticulated platelets are unstable. This study therefore assessed the validity of %IPF values obtained from stored patient samples. Our findings showed that %IPF values alter with storage; significant differences in %IPF values were obtained on stored samples compared with freshly analysed samples (p<0.001). It is therefore essential that in order to maintain the clinical utility of the %IPF, analyses should only be made on freshly drawn blood samples.

The selection of laboratory equipment

The last few years have seen dramatic changes in laboratory haematology. Technological developments with increasing levels of automation have resulted in a plethora of new instruments. The choice of which to buy, often confused by conflicting advice and persuasive salesmanship, must be balanced by the need for cost containment. This calls for an understanding of the principles of selection to ensure that the system that is chosen will provide reliable results in the most efficient manner at the lowest possible cost. Most of the instruments which are currently available perform their intended tasks reasonably well albeit with some inter-instrument differences, usually due to different operating procedures and different methods of calibration. The task is to find a system that performs the required tests correctly and reliably, fits into the work requirements of the laboratory and is accepted by the staff who will operate it, whilst its cost both capital and recurrent, should be within the department's financial constraints. The selection of laboratory equipment is thus a complex and time consuming task.

Comparative evaluation of three flow cytometers for reticulocyte enumeration

Flow cytometric determination of reticulocytosis is progressively replacing the manual microscopic method. We evaluated three flow cytometers (Becton Dickinson FACScan, Coulter EPICS Profile II, Ortho Cytoron Absolute) for reticulocyte enumeration, using thiazole orange. For each sample, 30,000 cells were analysed. In order to comparatively evaluate the three instruments, reticulocytes were counted by manually gating the erythroid population and evaluating the gated population for fluorescence characteristics. The different instruments showed good linearity and precision. No carry-over was observed. Orthogonal regression analysis of reticulocyte counts of 100 healthy blood donor samples and 108 haematological patient samples showed a good mutual comparability between all three instruments tested, although the paired t-test showed a significant difference between the Cytoron and both the FACScan and the Profile. Despite minor statistical differences, the three instruments can be considered equivalent for daily routine reticulocyte enumeration.

Evaluation of the utility of the HemoCue 301 haemoglobinometer for blood donor screening

BACKGROUND AND OBJECTIVES

Reliable blood donor screening requires more accurate measure of haemoglobin (Hb) than by either copper sulphate or the haemoglobin colour scale. The HemoCue haemoglobinometer has established a method for this, but it is considerably more expensive; a modified version (HemoCue 301) has now been developed with a cheaper reagent-free cuvette for use in budget-restricted situations. This report describes evaluation of the performance, the assessment of reproducibility and accuracy of this modified analyser against the reference technique for Hb measurement.

MATERIALS AND METHODS

Over 300 routine blood samples from specimens received routinely in a hospital laboratory were tested in accordance with the International Committee for Standardization in Haematology (ICSH) protocol. Accuracy and linearity were confirmed by the reference method with the WHO international haemoglobincyanide reference standard. Tests were also performed on selected samples for checking interference by biochemical abnormalities and leucocytosis. The effects of various sample storage conditions prior to testing were also tested.

RESULTS

Ninety per cent of results were within 4% of true values, 96% within 6% and in only three cases was the deviation > 10%, due to interference by bilirubinaemia and/or C-reactive protein. At an Hb value of 120 g/l for donor selection, there were no cases where the method would have been misleading.

CONCLUSION

HemoCue 301 provides a simple and reliable anaemia screen method, conforming to the requirements of CLIA'88 regulations; it is reliable for discriminating Hb values for donor acceptance. The main advantage is that the cuvettes are significantly cheaper than the previous models, and will not deteriorate in adverse climatic conditions.

Validation of the Beckman Coulter AcT 5 Diff Analyzer in a Reference Laboratory

At the Valle de Hebron Hospital's Central Laboratory, we have performed a study evaluating the performance, reliability, and practicability of the Beckman Coulter AcT 5 analyzer. The results observed with known controls showed within- and between-run imprecision of 1.05% to 6.97% for the basic hemogram parameters. With patient samples, the results were analogous, with within- and between-run imprecision of 1.33% to 5.98%. To complete the evaluation of the AcT 5 counter, we analyzed the influence of possible interfering factors such as the presence of jaundice, lipemia, hemolysis, platelet aggregates, and schistocytes on the results of the automated leukocyte differential as performed by the cell counter with the new chlorazol black stain. We studied the performance of the AcT 5 with regards to ease of use, speed, and cost. Finally, we evaluated the impact of introducing the AcT 5 counter into routine laboratory use as support to resolve problems raised with the Beckman Coulter GenS and LH-750 and the Bayer Advia 120 counters due to samples with interfering factors.

European Multi-Center Evaluation of the Abbott Cell-Dyn Sapphire Hematology Analyzer

This study presents the results of performance evaluations of the Cell-Dyn Sapphire (CD-Sapphire) undertaken by 3 study sites in Europe. These studies focused on the routine blood count analyses with specific consideration of precision and imprecision, linearity, inter-instrument correlations, and white blood cell differential and flagging efficiencies. The CD-Sapphire was compared to the Cell-Dyn CD4000, Bayer Advia 120, Beckman Coulter GenS, and reference microscopy.

Evaluation of the Sysmex Xe-2100 hematology analyzer in hospital use

The Sysmex XE-2100 (Sysmex Corp. Kobe, Japan) is a latest-generation hematology analyzer. Its optical and electrical measuring technology is improved by the addition of flux cytometry, fluorescence, and differential lysis. Its analytical performance in terms of precision, reproducibility, linearity, carryover, and time stability was found to be entirely satisfactory. In addition, the results of 500 complete blood counts and differentials correlated perfectly with those obtained by the Coulter STKS (Beckman Coulter, Villapointe, France). The comparison of 500 leukocyte differential count results analyzed in parallel with optical microscopy and the XE-2100 were surprising, and favorable to the XE-2100. This analyzer provides the user with an undeniable feeling of security concerning its reliability in detecting and identifying anomalies in the automated leukocyte differential count. With a sensitivity of 96%, a negative predictive value (NPV) of 98%, and a false-negative (FN) rate of 4%, the XE-2100 has perhaps reached the technological limits for a machine performing morphological recognition of normal and pathological blood cells.

Evaluation of a hematology analyzer with canine and feline blood

A semiautomatic electronic blood cell counter (Sysmex F-800:Toa Medical Electronics Europa Gmbh, Hamburg, Germany) was evaluated using canine and feline blood, following the International Committee for Standardization in Hematology protocol (ICSH, 1984). Precision and overall reproducibility were acceptable for all the parameters studied except for the feline platelet count, in which overlapping of erythrocyte and platelet populations prohibited determination of an accurate platelet count. Since carry-over from canine hematocrit values and platelet counts and from feline hematocrit values was unsatisfactory, the use of a blank diluent sample between different analyses was necessary. Linearity of the analyzer was acceptable in the studied range. Thirty canine and feline blood samples were analyzed using the Sysmex F-800 and a manual method. Correlations between both methods were acceptable for all the parameters, except for feline platelet count and erythrocyte indices for both species. In the storage study, red blood cell count and hemoglobin concentration were the parameters with the longest stability (72 hours at 4 degrees C and 25 degrees C) in both species. A statistically significant increase in MCV was obtained at 12 hours post-extraction in canine samples stored at 25 degrees C and at 24 hours in refrigerated samples. Feline leucocyte counts showed a downward trend at 12 hours post-extraction at both temperatures. Canine platelet count decreased significantly at 6 hours post-extraction in samples stored at 4 degrees C. During the evaluation period, Sysmex F-800 was user friendly and appeared well suited for routine canine and feline blood cell analysis.

Evaluation of the HemoCue for measuring intra-operative haemoglobin concentrations: a comparison with the Coulter Max-M

We compared haemoglobin concentration values obtained using a portable haemoglobinometer, the HemoCue, in the operating theatre with the results obtained by the Coulter Max-M in the laboratory. Haemoglobin concentrations were measured on 52 arterial blood samples obtained from 13 patients during aortic surgery, in theatre with the HemoCue and again by the Coulter Max-M. Twenty routine samples from the laboratory were also analysed by both methods. There was no significant difference between results, with a mean of 10.94 g.dl-1 and 10.90 g.dl-1 for the HemoCue and Coulter, respectively (p = 0.12, t = -1.99, df = 70). The limits of agreement of the two methods (mean difference +/- 2 SD) were -0.37 and +0.45 g.dl-1. The coefficients of repeatability of the 20 samples analysed in duplicate on each device were 0.26 g.dl-1 and 0.33 g.dl-1, respectively. The coefficients of variance were 0.74% (HemoCue) and 0.93% (Coulter). With adequate training and monitoring, the HemoCue provides comparable haemoglobin results for near-patient testing in theatre.

Evaluation of a haematological analyser (Sysmex F-800) with equine blood

A semiautomatic electronic blood cell counter (Sysmex F-800) was evaluated with equine blood, according to the protocol of the International Committee for Standardization in Haematology (ICSH, 1984). The precision and overall reproducibility were acceptable for all the parameters studied except for the platelet count, in which a coefficient of variation of 18.8% and 21.7% was obtained for within and between batch precision and 26.76% for overall reproducibility. Carry-over for the haematocrit value and platelet count was unsatisfactory, thus the use of a blank diluent sample between different analyses was necessary. Linearity of the analyser was acceptable in the range studied. A total of 100 equine blood samples were studied with the Sysmex F-800 and the manual method. The correlations between both Methods were acceptable for all the parameters. In the storage study, the red blood cell count and the haemoglobin concentration were the parameters with longest stability (72 h) at 4 degrees C and 25 degrees C. Platelet count decreased significantly at 3 h post-extraction in those samples stored at 4 degrees C. During the evaluation period, Sysmex F-800 was easy to handle and it is well suited for routine equine blood cell analysis.

Comparing methods of measurement: why plotting difference against standard method is misleading

When comparing a new method of measurement with a standard method, one of the things we want to know is whether the difference between the measurements by the two methods is related to the magnitude of the measurement. A plot of the difference against the standard measurement is sometimes suggested, but this will always appear to show a relation between difference and magnitude when there is none. A plot of the difference against the average of the standard and new measurements is unlikely to mislead in this way. We show this theoretically and by a practical example.

Urinary sediment analyzed by flow cytometry

A flow cytometer for the automated analysis of urinary sediment was designed, and its performance was examined by the evaluation of 821 specimens. Auramine O, a dye for DNA and RNA, was used for the staining of the sediment. Urine (5 ml or more) was processed by the instrument for sediment analysis. Conventional microscopic analysis was done for comparison. The RBC count, the WBC count, and the number of bacterial cells, epithelial cells, and casts found by the flow cytometer and by microscopy were compared. Correlation was high for all these results. The overall sensitivity, specificity, and efficiency (accuracy) in the items analyzed were 84.7%, 57.8%, and 67.2%, respectively. One hundred specimens could be analyzed by the instrument per hour. The instrument seemed useful for screening for urinary tract disorders to identify specimens that should be analyzed microscopically in routine laboratories.

Variability in absolute lymphocyte counts obtained by automated cell counters

There is increasing interest in the absolute lymphocyte count. This is partly driven by the need to obtain absolute values for lymphocyte subsets such as absolute CD4+ counts in human immunodeficiency virus (HIV)-infected persons. The absolute total lymphocyte count is usually determined in the routine hematology laboratory on a separate sample from the same patient specimen and then combined with percentage results from flow cytometry to obtain the absolute value of the lymphocyte subsets. We have studied analytic variability in the absolute lymphocyte determination and compared it to the variability of the total white blood count (WBC). In a series of 524 specimens, four different automated methods were compared to each other and to the traditional eye count differential. The automated methods were four widely used automated cell counters (Technicon H*1, TOA NE8000, Coulter STKS, and Abbott CD3000). The results indicate that analytic variability in the absolute lymphocyte counts, due, primarily, to method variability, is significant and is larger than the variability typically observed on interlaboratory trials of relative CD4 counts. These method biases cannot easily be reduced by calibration, since the cell classification algorithms are built-in features of the various cell counters. Analytic variability of the absolute lymphocyte counts was found to be 12.4% compared with analytic variability of only 4.9% for total WBC counts on the same samples. Our data suggest that more precise results would be obtained if flow cytometry results expressed each phenotype as a fraction of the leukocytes as well as total lymphocytes. Conversion to absolute values could then be accomplished through determination of the total WBC in the routine hematology laboratory.

Two-centre evaluation of the Abbott CD3500 blood counter

The CD3500 blood counter (Abbott Laboratories) is a 33 parameter fully automated blood counter that produces a five part differential count with flagging of leucocyte abnormalities. In this evaluation excellent correlation between CD3500 and Coulter STKR blood counter was found for all red cell and platelet parameters on the 221 samples tested. Studies of carryover, mixing efficiency and precision also gave excellent results. There was a good correlation with manual 400 cell differential counts for neutrophils, lymphocytes, monocytes and eosinophils for the 468 samples compared. Correlation of CD3500 and manual basophil counts was poor. Normal samples stored at 4 degrees C and analysed while cold showed satisfactory stability for WBC, RBC, Hb, MCV and platelets for 48 h and a stable differential for 24 h. Correlation with the differential count produced by the Coulter STKS showed good correlation for neutrophils, lymphocytes, monocytes and eosinophils; correlation with STKS basophils was poor. False positive flagging rate varied between 8.9% (Band and/or IG) and 0.9% (NRBC) depending on the nature of the flag; 5.8% of samples exhibited two or more false positive flags. No significant breakdowns were encountered during the period of the evaluation. The scatterplot displays of laser light scatter produced by the instrument provide an interesting adjunct to conventional morphology.

Evaluation of the Roche Cobas Argos 5Diff automated haematology analyser with comparison to a Coulter STKS

The performance of the Roche Cobas Argos 5Diff (Argos) automated haematology analyser was evaluated by comparison to manual blood film examination and a Coulter STKS (STKS) analyser. The Argos demonstrated excellent between and inter-batch imprecision for all parameters, except the MCHC, and good linearity for Hb, WBC and platelet count (PLT). After an initial fall the PLT, results were stable for up to six h at 18 degrees C in EDTA(K3) after which an increasing proportion of cells were classified as lymphocytes. Results of 239 patient samples analysed on both instruments, compared by linear regression, gave excellent correlation (r2 > 0.90) for most parameters with the exceptions of the MCHC (0.317), eosinophils% (0.756), monocytes% (0.48) and basophils% (0.002). 'Flagging' of cellular abnormalities by the Argos resulted in excellent sensitivity (97.5%), specificity (93.2%) and efficiency/agreement (93.2%), with fewer false positive and negative results than the STKS, although these differences were not statistically significant. The performance characteristics of the Argos were comparable to those of the STKS with a possible improvement in its flagging abilities.

A new development in haematological cell counting: the Sysmex NE-8000, automaton for cell count and physical five-part leukocyte differentiation

We compared the results of the Sysmex NE-8000 with those of the Sysmex E-4000 and the Technicon H-6000. Both for the whole blood cell count and the leukocyte differentiation we obtained intra- and inter-assay coefficients of variation fully comparable with those for other cell counters. The carry-over between samples was negligibly small. The linearity range was broad, which implies a universal application in routine haematological analysis. The numerical results from the Sysmex NE-8000 and the Technicon H-6000 corresponded closely, with exception of the mean corpuscular volume and the haematocrit, whereas these parameters showed excellent agreement between the NE-8000 and the E-4000. In the differentiation of leukocytes, the NE-8000 and H-6000 showed good correlation and conformity for lymphocytes, neutrophils and eosinophils; for monocytes and basophils the conformity was poor. We also found a good correlation between the NE-8000 and E-4000 for lymphocytes and neutrophils, whereas the correlation was less for the middle cell ratio and the sum of monocytes, eosinophils and basophils. Furthermore, we compared Receiver Operating Characteristic curves for the different leukocyte subtypes on the NE-8000, the H-6000 and the E-4000, and investigated the flagging frequency in inpatients, outpatients and blood donors.

[Automated microfluorometric absolute count and maturation analysis of reticulocytes]

The absolute reticulocyte count and the maturation distribution of blood reticulocytes can be obtained by automated microfluorometric analysis in a deposit system called AURAS (Automated Reticulocyte Analysis System). Moreover visual measurements are possible on the same specimen for cell individual control. Visual reticulocyte counts are of high reproducibility and accuracy and therefore deliver practicable reference data. Results from experimental work indicate the value of maturation distribution changes with respect to Erythropoietin effects.

Coincidence correction in red blood cell counting

A method has been developed for accurate correction of red blood cell count for coincidence in aperture-impedance electronic blood cell counters. It is based on extrapolation of the slope of regression of the counts which are obtained with sequential dilutions of the samples.

An evaluation of the Coulter VCS differential counter

An evaluation of the Coulter VCS (volume, conductivity, light scatter) automated differential counter demonstrated satisfactory correlations with manual 800-cell differential counts for neutrophils, lymphocytes, monocytes and eosinophils. For the detection of abnormal cells, 12.2% of samples gave false-negative results on the VCS, and 13.4% gave false-positive results. However, only 0.8% of the false-negatives would be expected to be picked up by a standard 100-cell manual differential count. Carry-over accorded to manufacturer's specifications and throughput was 60 samples/h. Reference normal ranges have been established and the instrument's precision and performance with leucopenic and neonatal blood samples assessed.

Guidelines on selection of laboratory tests for monitoring the acute phase response. International Committee for Standardization in Haematology (expert panel on blood rheology)

These guidelines refer to laboratory tests for monitoring changes in acute phase proteins in patients with an inflammatory response to tissue damage. Quantitative measurements of acute phase proteins are a valuable indicator of the presence, extent, and response of inflammation to treatment. When short term (less than 24 hours) changes in the inflammatory response are expected, quantitative assay of C reactive protein is the test of choice. The hyperproteinaemia that develops in response to a longer term (more than 24 hours) inflammatory response is complex and may vary from one disease to another. A test that is sensitive to the combined effect of several plasma proteins is therefore indicated, and appropriate tests include the erythrocyte sedimentation rate and plasma viscosity--the latter having several advantages. Tests for monitoring short term and long term changes in acute phase proteins are complementary and should be used for different clinical purposes; no one test is ideal for all clinical situations. A quality control programme is an essential component of laboratory tests for monitoring the acute phase response.

An evaluation of the Coulter Counter Model T660

An evaluation of a Coulter Counter Model T660 has been carried out. This instrument is a compact, fully automated, blood cell counter which measures WBC, RBC, Hb, haematocrit, MCV and platelet count on a 100 microliter sample of whole blood. The instrument was assessed during one month of regular use. One possible microbiological hazard was detected, which could be corrected by an instrument modification. No mechanical hazards were identified. The instrument as supplied produced some inaccurate WBCs; this malfunction appeared to be consequent on a design fault relating to the burn circuit of the white cell aperture and following instrument modification performance was considerably improved. Results produced were broadly comparable with those produced by a Coulter Counter Model S Plus IV. Precision was satisfactory. Deviations from linearity on dilution were not sufficient to be of practical importance. Carryover was satisfactorily low. Time-lapse of up to 48 h did not introduce inaccuracy of sufficient magnitude to be of practical importance. Throughout varied from 52 to 63 specimens/h. Following instrument modification the overall assessment was that the T660 was easy to operate, reliable, and clinically useful.

An evaluation of the Coulter Counter Model S880

An evaluation of a Coulter Counter Model S880 has been carried out. Certain findings have been further evaluated on a second instrument. Several safety hazards have been identified which could be corrected by minor modifications of the instrument or the mode of operation. Precision was found to be generally satisfactory, though for the platelet count and the WBC it was sometimes worse than specified. Most parameters were not strictly linear on dilution but only for the MCV and the MCH was the deviation from linearity sufficient to be of practical importance. Carryover was satisfactory. Results were generally comparable with those of a Coulter Counter Model S Plus IV. Estimates on all parameters were satisfactory on blood samples stored up to 24 h at either 4 degrees C or room temperature; beyond 24 h inaccuracy was seen particularly in the WBC, platelet count and MCV. Throughput was 60 to 70 samples/h in the whole-blood mode. Start-up and shut-down times were acceptably short. The instrument was assessed as acceptable and clinically useful, although reliability was somewhat less than expectations.

An evaluation of the Sequoia-Turner Cell Dyn 900

A formal evaluation of the Sequoia-Turner Cell Dyn 900, a compact eight-parameter semi-automated blood cell counter, was carried out in a small paediatric haematology laboratory. The instrument's precision, linearity and carry-over were adequate. Comparison with a Coulter ZF6 system plus visual platelet count showed good agreement, and results in the UK National External Quality Assessment Scheme also compared well with 'all methods' values. Throughput was assessed at 54 eight-parameter counts per hour. The machine proved to be reasonably economical, highly reliable and easy to operate. It was popular with staff and can be recommended, particularly for the smaller laboratory.

An assessment of the Ortho ELT-800 WBC and three-part WBC screen

The ELT-800 WBC and three-part WBC screen have been evaluated. Technical assessment showed each to be satisfactory but in a small number of samples, the total WBC was found to be incorrect. Discrepancies were found in some cases of chronic lymphatic leukaemia, sickle cell disease and paraproteinaemia. The reasons for these differences are discussed. In the population studied, an accurate WBC screen was obtained on 87.3% of samples. Initial instrument WBC screen rejection occurred on 12.7% but in only 2.1% could no explanation be found to account for this.