International Committee For Standardization In Haematology Research Articles

Evaluation of humoral pattern detection performance of Mindray BC-6000PLUS blood analyzer based on WS/T 662-2020.

Manual microscopic examination is the gold standard of humoral cell count test. However, it has some limitations and cannot fully meet clinical needs. Compared with the manual method, the automatic blood cell analyzer has the advantages of a high degree of automation, minimal error, high speed, high precision, and easy standardization. This study intends to verify the detection performance of the body fluid model of the Mindray BC-6000PLUS automatic hematology analyzer. This study was performed in accordance with the International Committee for Standardization in Haematology (ICSH) Hematology Analyzer Evaluation Guide (version 2014) and the requirements of WS/T662-2020 "Clinical humoral examination technique". The humoral white blood cell-body fluid (WBC-BF), humoral red blood cell-body fluid (RBC-BF), monocyte (MN), polymorphonuclear (PMN) were measured to verify the performance indicators of the instrument, including background counting, intra-batch precision, accuracy, carrying contamination rate, and linear range. Referring to the WS/T514-2017 (Establishment and verification of detection capability for clinical laboratory measurement procedures), the limit of blank (LoB) and limit of detection (LoD) values of WBC-BF and RBC-BF in the humoral mode of the instrument were established. The blank count of WBC-BF and RBC-BF, and contamination of Mindray BC-6000PLUS analyzer were zero; the coefficient of variation (CV) of intra-batch precision at different levels of each item was less than 10%. There was a high correlation between instrument test results and manual microscopic examination results (r>0.95). The linear range of the instrument was wide, and the linear verification parameters was good (R2>0.999). The LoB value and LoD value of WBC-BF established by the instrument were 0×109/L and 0.004×109/L, respectively. The LoB value and LoD value of the RBC-BF established by the instrument were 0×1012/L and 0.004×1012/L, respectively. The lower detection limits of WBC-BF and RBC-BF were set as 0.004×109/L and 0.004×1012/L, respectively. All performance indicators of the Mindray BC-6000PLUS automatic blood analyzer met the requirements of the manufacturer's criteria. This instrument can fulfill the requirement of body fluid sample routine test in clinical practice.

Factors Influencing Measurement of Serum Iron Concentration in Dogs: Diurnal Variation and Hyperferritinemia

ABSTRACTWe evaluated diurnal variation and hyperferritinemia as factors that influence the values of serum iron concentration in dogs, using the International Committee for Standardization in Hematology (ICSH) colorimetric method. Serum iron levels were significantly higher in the morning than in the evening in 6 clinically healthy beagle dogs, and the maximum decrease in serum iron concentration was 47.3%. Moreover, the change in serum iron concentrations in 22 clinical canine cases with various serum ferritin levels was evaluated by immunoprecipitation of ferritin. The rate of decline in the serum iron concentrations positively correlated with serum ferritin levels (r=0.48, P=0.024). These results show that it is necessary to consider the sampling time and serum ferritin level for accurate interpretation of serum iron concentrations in dogs.

Evaluation of Mindray BC‐3600 hematology analyzer in a university hospital

The BC-3600 Auto Hematology Analyzer (hereinafter call BC-3600) is a quantitative, automated hematology analyzer and leukocyte differential counter for In Vitro Diagnostic Use in clinical laboratories. The analyzer was evaluated and compared with the Mindray BC-3200 3-part differential (BC-3200) and Sysmex XE-2100 5-part differential (XE-2100) Hematology Analyzer in the hematology laboratory of a university hospital. The BC-3600 was evaluated according to guidelines published by Clinical and Laboratory Standards Institute (CLSI), the International Committee for Standardization in Hematology (ICSH), and Department of Food and Drug Administration (FDA). There were no background, minimal carryover (<0.5%), and excellent linearity for white blood cell (WBC), hemoglobin (Hb) level, red blood cell (RBC), and platelet (PLT) counts (r>0.999). Precision was good at all levels for the routine cell blood count (CBC) parameters: CV% being ≤2.0, except for platelet count (PLT) at the low level with CV% of ≤5.0% and WBC at the low level with CV% of <3.0%. Correlation between the BC-3600 and BC-3200, XE-2100 were excellent (r>0.99) for all major CBC parameters. It is concluded that the overall performance of the BC-3600 is excellent and compares well with that of BC-3200 and XE-2100.

The Esr Test: An Old Test With New Contents

The Esr Test: An Old Test With New ContentsThe erythrocyte sedimentation rate (ESR) remains one of the most widely used laboratory tests. Its clinical usefulness and interpretation are in the monitoring of inflammatory diseases, in particular rheumatoid arthritis, temporal arteritis and polymyalgia rheumatica. At present, the reference method for measuring the ESR proposed by the International Committee for Standardization in Haematology (ICSH) utilizes EDTA-anticoagulated-undiluted blood to perform the test using the method described by Westergren in 1921. Current interest in the methodology focuses on the development of an automated closed system that allows the determination of the sedimentation rate with selected working methods, using a single sample for more than one haematological test, improving the bio-hazardous aspects of the testing procedures. As a consequence, standardization becomes necessary. ESR results should be reliable, despite the increased number of different methods and testing variables. Control materials and External Quality Assurance Schemes are now available, and should be used. In conclusion, innovative techniques may improve the appropriateness and usefulness of ESR in clinical practice, but in addition, they need to guarantee the traceability of results in comparison to the reference method in order to ensure comparability of results among different clinical laboratories.

Comparative Study of Erythrocyte Sedimentation Rate (ESR) Using Trisodium Citrate, Normal Saline and Whole Blood in Ethylene Di Amine Tetra Acetic Acid (EDTA)

Erythrocyte sedimentation rate (ESR) was carried out on 200 apparently healthy individuals (131 males and 69 females) in Ekpoma using trisodium citrate, normal saline diluents and whole blood suspension in EDTA without any diluents. The Westergren method was adopted for this study as recommended by the International Committee for Standardization in Haematology (ICSH). The tests were read at 30 minutes and 1 hour intervals and results recorded as mm in 30mins and mm in 1hr respectively. The Mean ± SD of ESR values in males using trisodium citrate and normal saline were 11.99±9.48 and 12.12±9.46, while for females it was 13.69±8.5 and 13.97±8.97 respectively. This difference was statistically significant (P< 0.05). There was also a statistically significant difference between the ESR values obtained using trisodium citrate and whole blood (P< 0.05). Males had lower ESR values compared to females. There was a statistically significant difference between the ESR values obtained in 30mins and 1hour (P< 0.05). In conclusion, the use of normal saline and whole blood cannot be a good substitute for trisodium citrate in estimating ESR. Secondly, ESR is time dependent; therefore, the conventional time of 1 hour should be maintained.

Erythrocyte pyruvate kinase deficiency: relations of residual enzyme activity, altered regulation of defective enzymes and concentrations of high-energy phosphates with the severity of clinical manifestation.

The defective enzymes of 54 patients with pyruvate kinase (PK) deficiency were characterized according to the recommendations of the International Committee for Standardization in Haematology (ICSH). The erythrocyte PK activity in whole blood was calculated considering the 16-fold higher activity of the reticulocyte enzyme (AR) compared to the erythrocyte enzyme (AE). The following parameters turned out to give a good correlation to the degree of haemolytic anaemia and can therefore serve as a prognostic tool: All patients with a severe course of the disease had residual erythrocyte PK activities less than 33% of the normal enzymes (percentage activity), and patients with mild haemolytic anaemia exhibited residual activity values below and above this threshold value. Studies of enzyme cooperative showed that positive cooperative or mixed cooperative phosphoenolpyruvate (PEP) binding with a predominant positive cooperative part appeared in all cases with a mild clinical course, and about one-third of the severe ones. Negative cooperativity or mixed cooperativity with predominant negative cooperative part was observed only with severe haemolytic anaemia. Furthermore, the determination of glucose-6-phosphate (G-6-P) turned out to be a good prognostic criterion, i.e. all patients with mild clinical course exhibited G-6-P-concentrations lower than 0.11 mumol/l red blood cells. In the case of patients with severe haemolytic anaemia, about 80% showed values higher than 0.11 mumol/l RBC.

Establishment of the national standard materials for haemiglobincyanide

Objective To establish the national standard materials for haemiglobincyanide (HiCN) for the traceability assays of hemoglobin. Methods HiCN national standard materials were established according to the document of International Committee for Standardization in Haematology (ICSH). The standard materials were certificated according to ISO Guide 35, including homogeneity and stability. Then they were characterized by the calibrated spectrophotometer which can be traceable to National Institute of Standards and Technology (NIST). The international reference materials of HiCN were compared with the result of the WHO reference laboratory to confirm the reliability. Results The uncertainty of the HiCN standard materials was 0.000 4 g/L and the variation coefficient (CV) was 0.09%. The uncertainty of long-term stability was 0.000 6 g/L; the certificated value of the standard materials was 0.615 9 g/L with uncertainty of 0.000 4 g/L. The combined uncertainty was 0.000 9 g/L and the expanded uncertainty was 0.001 8 g/L when the cover factor was 2. The relative error was 0.08% between the result of the standard materials and the international certificated value. Conclusion The homogeneity and stability of the standard material is acceptable and the method of characterization is accurate and reliable. Key words: Themoglobins; Reference standards; Spectrophotometry

Protocol for evaluation of automated blood cell counters

This protocol is proposed for the evaluation of automated blood cell counters to assess the performance, advantages and limitations of such instruments. It is based on the International Committee for Standardization in Haematology (ICSH) 'Protocol for type testing equipment and apparatus used for haematological analysis' (1978a) and the British Committee for Standardization in Haematology 'Guidelines for the evaluation of instruments used in haematology' (Shinton, England & Kennedy, 1982). The document has been prepared by the ICSH Panel on Cytometry after discussion with colleagues. This tentative protocol will be reviewed 1 year after publication, in accordance with the ICSH rules, before it is adopted as a definitive standard.

Performance evaluation of BC‐3200 hematology analyzer in a university hospital

The BC-3200 automated hematology analyzer was evaluated and compared with the Beckman-Coulter AcT (Ac.T diff 2) 3-part differential hematology analyzer. The BC-3200 was evaluated according to guidelines published by the International Committee for Standardization in Hematology (ICSH), Clinical and Laboratory Standards Institute (CLSI), and Department of Food and Drug Administration (FDA). The results demonstrated no background, minimal carryover (<0.5%), and excellent linearity for hemoglobin (Hb) level, white blood cell (WBC), red blood cell (RBC), and platelet (PLT) counts (>0.998). Precision was generally acceptable for all complete blood count (CBC) parameters; coefficients of variation (CVs) were within the manufacturer's claims and CVs of CBC parameters, including WBC, RBC and PLT counts, Hb and mean corpuscular volume, were <6%. Correlation between the BC-3200 and Ac.T diff 2 was excellent (r > 0.98) for all major CBC parameters (WBC, RBC, and PLT counts and Hb). We conclude that the overall performance of the BC-3200 is excellent and compares well with that of the Coulter Ac.T diff 2.

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

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. 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. 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. 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.

Reference Intervals and Age‐related Changes for Platelet Count, Mean Platelet Volume and Plateletcrit in Healthy Pre‐weaning Piglets in Italy

Platelet count (PLT) mean platelet volume (MPV) and plateletcrit (PCT) were determined for 117 Landrace x Large White piglets aged 3-21 days; counts were performed with an automated blood cell counter (ABX Pentra 120). Reference values were estimated following the guidelines of the International Federation of Clinical Chemistry (IFCC) and the International Committee for Standardization in Haematology (ICSH). The calculated central 95% reference limits for PLT was 49.9-516.2 x 10(9)/1, for MPV 6.71-9.91 fl and for PCT 0.009-0.395%. When observations are divided into three age groups (about 1 week each) there is an increase in mean PLT count and PCT in 2-week piglets, and a decrease in MPV from the first to the third week of life. These reference values provide guidelines for interpreting for experimental and clinical observations, as well as for monitoring of the health status of similar aged piglets determined using automated impedance-light focusing methodology.

Comparison of Bathophenanthroline Sulfonate and Ferene as Chromogens in Colorimetric Measurement of Low Hepatic Iron Concentration

Sensitive and accurate measurement of hepatic iron concentration (HIC) is required to investigate liver fibrogenesis (1) and its influence on the outcome of interferon therapy for chronic viral hepatitis C (2)(3). Hepatic iron content can be measured by a quantitative chemical method and/or evaluated by semiquantitative histologic scoring. Quantitative chemical methods assess all liver iron forms, whereas histologic scoring evaluates only the hemosiderin form. A colorimetric method using bathophenanthroline sulfonate as chromogen was recommended in 1978 by the International Committee for Standardization in Hematology (ICSH) for determination of serum iron (4)(5). It was adapted by Barry and Sherlock (6) to the determination of HIC, and we recently evaluated it for measurement of low HIC (7). In 1990, the ICSH replaced bathophenanthroline sulfonate with ferene, a more sensitive chromogen, in the determination of serum iron (8). The aim of the present study was to evaluate the replacement of bathophenanthroline sulfonate with ferene to improve the sensitivity of the colorimetric determination of low HIC. We used samples of a frozen Wistar rat liver for quality control and determination of reliability criteria of both assays. We compared the results obtained with the two chromogens on 66 liver biopsies from patients with chronic liver diseases hospitalized in the Department of Hepatogastroenterology of the Pitie-Salpetriere Hospital. The clinical diagnoses of these patients are summarized in Table 1⇓ . We determined the CV for HIC measurements on two separate samples from the same liver specimen for each chromogen on 38 human liver biopsies. Histologic iron scoring was according to the method of Deugnier et al. (9); among the 66 biopsies, 20 had no stainable iron (score of 0), and the 46 others exhibited iron overload (score ≥6). Biopsies were fixed in 40 g/L formaldehyde and embedded in paraffin as part of …

Length of sedimentation reaction in undiluted blood (erythrocyte sedimentation rate): variations with sex and age and reference limits.

Although the length of sedimentation reaction in blood (LSRB) (commonly, but improperly called erythrocyte sedimentation rate, ESR) has long been used in clinical laboratories because it is simple and low-cost, its sensitivity and specificity are unsatisfactory. Usually, the values are reported using the Westergren method with sodium citrate-anticoagulated specimens. We used a new procedure, the TEST1, which measures the length of sedimentation reaction in undiluted K3EDTA anticoagulated blood samples following ICSH (International Committee for Standardization in Haematology) recommendations. Samples obtained from 840 reference individuals (430 females and 410 males, mean age 44 and 46.5 years respectively, range 1 to 90 years) were utilised to estimate the reference limits. The subjects, classified by sex, were subdivided into four statistically different age groups to determine the reference limits (2.5th and 97.5th percentiles). Sex difference was statistically significant in two age groups, from 14 to 50 (p < 0.0001) and from 50 to 70 years (p < 0.01). We did not observe significant sex difference within the age bracket from 1 to 14 years and from 70 to 90 years. In both sexes LSRB values increased with age, in significant correlation with fibrinogen concentration (p < 0.0001), and became significantly higher in subjects older than 70 compared to all the younger subjects (p<0.01 in females and p < 0.02 in males). Thus, we defined adequate reference ranges in elderly.

Preparation of lyophilized partial thromboplastin time reagent composed of synthetic phospholipids: usefulness for monitoring heparin therapy

To contribute to the development of a reference reagent for monitoring heparin therapy, a lyophilized partial thromboplastin time (PTT) reagent was prepared from synthetic dioleoylphosphatidylcholine, dioleoylphosphatidylserine, and dioleoylphosphatidylethanolamine, with colloidal silica as activator. The reagent, coded 91/558, was contained in sealed glass ampoules; it deteriorated in a heat degradation experiment, but its activity remained constant for at least 4 years when stored at -70 degrees C. Within- and between-run precision with this reagent complied with the requirements proposed by the International Committee for Standardization in Haematology (ICSH) Panel on PTT. The response of this reagent and of two other reagents to heparin added to pooled normal plasma was nonlinear. Citrated samples from 58 patients receiving intravenous heparin and from 24 apparently healthy volunteers were tested with reagent 91/558, with Automated APTT (Organon Teknika), with Manchester APTT reagent, with an antifactor Xa assay, and with an anti-factor IIa assay. The correlation of APTT with anti-Xa and anti-IIa activity was poor. The best correlation was observed between reagent 91/558 and the Organon Teknika reagent. Correlations were improved when individual patients' samples were replaced by pooled plasmas from heparinized patients, in whom the effect of oral anticoagulation was minimal. These results suggest that preparation of a lyophilized synthetic phospholipid reagent is feasible for use in monitoring heparin therapy.

When is a serum iron really a serum iron? The status of serum iron measurements

Although serum iron determinations play an important role in the diagnostic process, the accuracy of routine methods is suspect. The poor performance of currently used methods is well documented in the quarterly College of American Pathologists survey reports. Compared with the 1990 method of the International Committee for Standardization in Haematology (ICSH), the 1978 ICSH Reference Method shows a +3.4% bias and the standard method of the National Committee for Clinical Laboratory Standards shows a -17.8% bias for iron results. All routine methods checked--DuPont aca, Abbott TDx, Kodak Ektachem (except one lot), BM/Hitachi 717, and Synermed--show a negative bias over the entire analytical range, a significant negative intercept, and extremely poor correlation with the 1990 ICSH method for iron values < 750 micrograms/L. Individual discrepancies of several hundred percent were observed. Imprecision of the methods is not the reason for these discrepancies. We question whether most routine methods measuring low iron concentrations provide results sufficiently reliable for confirmation of iron deficiency.

Rapid determination of erythrocyte pyruvate kinase activity

We report a new potentiometric method for determining pyruvate kinase (PK). Enzymatic activity is measured by monitoring the change in pH produced in the reaction buffer under International Committee for Standardization in Haematology (ICSH) standardized assay conditions, and the lactate dehydrogenase reaction is automatically subtracted in each measuring cycle. The analysis, performed at 37 degrees C, requires a 10-microL sample (isolated erythrocytes or whole blood) and is completed in 2.5 min. The intra-assay CV is < 4% (PK between 3 and 35 U/g Hb); the interassay CV is 4.0% (PK 15 U/g Hb); results are linear from 3 to 30 U/g Hb. A good correlation with the ICSH reference method (x) was found: y = 1.011x - 0.05; n = 32; r = 0.9939; Sylx = 0.75 (units: U/g Hb). The reference intervals of the PK activity in isolated erythrocytes (RBC-PK) were estimated in 89 normal subjects. We found that women possess a higher RBC-PK than do men (P < 0.0001) and that the biological variability (CVb) of RBC-PK is 13.5%. Applications of the proposed method to the hematological routine are reported.

CHARACTERISTICS OF THE EXTERNAL QUALITY ASSESSMENT (EQA) SCHEME FOR HAEMATOLOGY IN SPAIN

Ensuring reliable results of the tests which are performed in large haematology laboratories is essential because of the problems resulting from the use of complex automated instruments and the ever increasing workload. The Spanish Haematology EQA Scheme started in 1984 with 56 laboratories, a number which rose to 332 in 1989. The general scheme follows the guidelines established by the International Committee for Standardization in Haematology (ICSH) with participants from Public Health (57.9%) and Private (42.1%) laboratories. Surveys are performed monthly and on each occasion the following samples are prepared and sent by the Organizing Center (Haematology Laboratory Department, Hospital Clinic i Provincial of the University of Barcelona): whole blood for full blood counts (FBC), platelet suspensions (or equine total blood) and lyophilized plasma for prothrombin time (PT), partial thromboplastin time (PTT) and fibrinogen (F). After preparation, control materials are sent to participant laboratories where the requested tests are performed and the results reported back to the Organizing Center for statistical analysis. For result evaluation, laboratories are divided into four to eight groups depending on the methodologies used. Individuals results are assessed against a consensus value (mean) deviation index (DI) from the mean, coefficient of variation (CV) and Youden diagram for all results and groups of each parameter. Between 58.3 and 74.5% of laboratories responded. For WBC, the CV improved from 17 to 7%, for platelets from 34.4 to 24.3%. For coagulation tests CV was 18.1% for PT, 16% for PTT, and 26% for fibrinogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of serum iron by aas: Deproteinization versus direct analysis

Atomic absorption spectroscopy (aas) offers sensitivity for the trace metal analysis of biological materials. Flame or electrothermal atomization (eaas) have been used depending on analyte concentration and the amount of sample required for the analysis. Most methods proposed for the routine determination of serum iron by aas involve either a deproteinization by acids [l-6] or dilution of the serum sample [7-111. Deproteiuization has the purpose of removing protein and haemoglobin iron which interfere in the determination of transferrin-bound iron. Higher iron concentrations were found [2,7] when serum was only diluted, than when it was deproteinized, possibly due to iron contamination due to non-visible haemolysis [12]. Enhancement of up to 50% can result from non-visible haemoglobin and over 100% from slight visible haemolysis. On other hand, it is desirable to avoid deproteinization, not to minimize contamination, to simplify the procedure, and to exclude co-precipitation of iron and proteins as well as the incomplete separation of iron from proteins [7]. The accuracy of serum iron assays has been checked by recovery tests [1,13], comparison with independent analytical methods [2,5-g] and validation with quality control serum or certified material [9]. According to the last recommendations of the International Committee for Standardization in Haematology (ICSH) [14], iron in reference materials should be assayed by independent methods such as aas, and serum for reference materials must be collected with stringent precautions against haemolysis. This latter recommendation is to prevent the liberation of iron from lyophilized haemoglobin in reconstituted serum.

Standardization and harmonization of the blood count: The role of International Committee for Standardization in Haematology (ICSH)

Scientific principles of standardization were first applied in haematology in 1963 when the International Committee for Standardization in Haematology was established with a primary objective to improve the measurement of haemoglobin. Subsequently, ICSH has established Expert Panels on a wide range of haematological topics, including especially a Panel on Cytometry. The purpose of haematological standardization is to obtain precision, accuracy, specificity and harmonization of results between different laboratories in all countries and also between different instruments or methods in the same laboratory. To achieve these objectives ICSH sponsors collaborative studies by scientists from academic centres and from industry and uses a consensus procedure for establishing standards on the basis of the scientific data, followed by an educational programme to ensure that the standards are adopted worldwide. ICSH defines material standards and standardized methods. Material standards are classified as primary international standards, certified reference materials, secondary standards and calibrators. These must be distinguished from control preparations which are intended exclusively for quality control. Standardization of methods must also be considered at four levels: definitive, reference, selected and routine. Each has a place in practice but their roles must be clearly defined. ICSH has an established protocol for evaluation of automated blood cell counters. This defines the levels of precision and accuracy of instrument performance. It is also necessary to assess "clinical utility". The main requirement of the practising haematologist is clinical reliability and harmonization of results for comparability. One of the major functions of ICSH is to provide an interface for collaboration between the manufacturers who develop the instruments and the users in order to achieve this goal.

Red cell deformability and haematological disorders

Blood rheology is the science of the flow and deformation of blood. Clinically, blood rheology is important because circulatory resistance has two major components, vascular and rheological. In large vessels, blood rheology should be considered in terms of bulk flow, the viscosity of blood depending mainly on red cell concentration and plasma viscosity and, to a lesser extent, on red cell deformability and aggregation. In the microcirculation, where cells must deform to pass through narrow capillaries, cellular rheology (i.e. the deformability of individual cells) is a major determinant of resistance to flow. This ability to deform is also a determinant of the cell's survival time in the circulation. The deformability of the red cell is essentially linked to its structure (i.e. its cellular geometry, membrane properties and cytoplasmic viscosity); thus structural abnormalities, as found in some haematological disorders, can be expected to affect blood flow in the microcirculation and/or red cell lifespan. Blood rheology is a relatively new discipline as applied to the practice of haematology. In 1985 the International Committee for Standardization in Haematology (ICSH) established an Expert Panel on Blood Rheology which has subsequently issued guidelines on the measurement of blood viscosity and erythrocyte deformability 1 and on tests such as erythrocyte sedimentation rate and plasma viscosity that are used to monitor the acute phase response in inflammatory disease. 2 Rheological methods now have sufficiently good sensitivity and specificity for their application to a wide variety of clinical disorders. This review illustrates their potential application to haematological disorders that cause abnormal deformability of red cells.