Search

We compared the analytical performance of a new point-of-care glucose meter specifically designed to automatically correct for hematocrit level and other interference factors with 3 commonly used glucose meters. We evaluated all 4 hospital-based glucose meter technologies for inaccuracy, imprecision, and analytical interferences likely to be encountered in patients with critical illness. In addition, we compared the performance of this new meter with one currently in use in our neurosurgical intensive care unit (ICU) to evaluate conformity to the International Organization for Standards 15197 criteria. Imprecisions, both within run and day to day, were evaluated on all the 4 glucose meters. Inaccuracy (bias) of the meters and analytical interference were evaluated by comparing results from whole blood specimens with results from plasma samples obtained from these whole blood specimens run on a hexokinase reference method. Analytical accuracy was assessed with glucose specimens spiked with different interference factors. Clinical accuracy was assessed on 95 whole blood specimens collected from patients admitted to a neurosurgical ICU ward. Imprecision and method correlation studies demonstrated slight differences in the degree to which the meters correlated with the hexokinase reference method. Paracetamol showed significant interference with 1 of the 4 meters tested. Ascorbate showed significant interference with 3 of the 4 meters. Hematocrit level also affected the correlation between whole blood and plasma hexokinase glucose results on 3 of the 4 meters tested. Assessment of clinical accuracy demonstrated that only 1 of the meters met the International Organization for Standards 15197 criteria when applied to neurosurgical ICU patients. Correlation with plasma hexokinase values and hematocrit level interference are the main variables that differentiate glucose meters. A meter that directly correlates with the plasma hexokinase glucose reference method over a wide range of glucose concentrations and minimizes the effects of hematocrit level provides more reliable data as an adjunct to intensive insulin therapy in patients with critical illness. Of the 2 meters studied in the neurosurgical ICU, only the StatStrip (Nova Biomedical Corporation, Waltham, Mass) demonstrated a total error that was within the acceptable limits.

Misidentification and Other Preanalytical Errors The largest number of laboratory errors occur in the preanalytical phase and are mainly due to educational and organizational reasons. The experience of our institution, as well as the results of an Italian interlaboratory effort to detect and reduce errors/risk of errors in laboratory medicine will be illustrated.

Clinical laboratories have undergone major changes due to technological progress and economic pressure. While costs of laboratory testing continue to be the dominant issue within the healthcare service worldwide, quality, effectiveness and impact on outcomes are also emerging as critical value-added features. Five Italian laboratories are therefore promoting a network of excellence by investigating markers of effectiveness of laboratory services and sharing their experience of using them in clinical practice. In the present study we report preliminary data on indicators of quality in all phases of the so-called total testing process, the key to evaluating all phases of the total testing process, including the appropriateness of test requests and data interpretation. Initial findings in evaluating pre-analytical causes of specimen rejection in three different laboratories and the effects of introducing three laboratory clinical guidelines are reported. These data should stimulate debate in the scientific community and encourage more clinical laboratories to use the same indicators to improve clinical effectiveness and clinical outcomes within the healthcare service.

The urokinase plasminogen activator receptor (uPAR) fragments D1 and D2D3 are often found in biological fluids from normal individuals and patients of cancer and other diseases. The D2D3 fragment may possess chemotactic activity depending on its N-terminal sequence. We have developed a sensitive and specific immunoassay for the chemotactic form of D2D3 and show that its level can be measured with high specificity and sensitivity in human serum and urine. Synthetic peptides (residues 84–92) derived from the linker region between domains 1 and 2 of uPAR were used as immunogens to generate mouse monoclonal antibodies. Recombinant soluble uPAR (D1D2D31–277) was used to immunize rabbits to obtain polyclonal antibodies. A sandwich-type immunofluorimetric assay was developed with these antibodies. The assay specifically measures D2D3 containing the 84–88 residues, has a detection limit of 0.25 ng/ml and shows no cross-reactivity with D2D393–274. The assay is linear at 0–30 ng/ml, with an intra-assay CV of 10% (n = 20), inter-assay CV of 15% (n = 9) and a recovery of D2D384–274 added to urine samples of between 94% and 105%. A statistically significant difference level of D2D384–274 was found in two groups of tumor patients versus healthy volunteers (p ≤ 0.009 in colorectal carcinomas and p ≤ 0.036 in prostatic carcinomas). For the first time, monoclonal antibodies, detecting the chemotactic form of uPAR, D2D384–274, have been produced. The immunofluorimetric assay will quantitate uPAR chemotactic fragments in biological samples, including serum and urine, and evaluate their diagnostic or prognostic potential in clinical studies.

Molecular diagnostics is being revolutionized by the development of highly advanced technologies for DNA and RNA testing. One of the most important challenges is the integration of microelectronics to microchip-based nucleic acid technologies. The specific characteristics of these microsystems make the miniaturization and automation of any step of a molecular diagnostic procedure possible. This review describes the application of microelectronics to all the processes involved in a genetic test, particularly to sample preparation, DNA amplification and sequence variation detection.

Semen sample analysis is routinely performed by microscopical evaluation and manual techniques by laboratory operators; the analysis is affected by a wide imprecision related to variability among observers, influencing its clinical validity. Our aim was to automate sperm analysis with the use of flow cytometry for evaluation of cell counts and typing and with the use of a new membrane-permeant nucleic acid stain for evaluation of sperm viability. Statistical analysis of the comparison between manual and automated methods for sperm counts was performed by the Bland and Altman method; the mean difference was 0.243 × 106 sperms/mL. The precision of the flow cytometric analysis was evaluated with whole sperm; the between-run CV was 7.5% and the within-run CV was 2.5%. Data observed suggest that flow cytometric sperm analysis, with high precision and accuracy and low costs, can be proposed for routine use in clinical laboratories.

A simple and rapid RP-HPLC method for the direct determination of ceftazidime (a β-lactam antibiotic) in agar (Mueller Hinton Agar-II) was developed. The method, characterised by good precision (C.V.

Cortisol, testosterone, free testosterone and the ratio between free testosterone and cortisol (FTCR) were monitored in six athletes participating in a marathon starting at 3,860 and finishing at 3,400 m, having reached the top at 5,100 m altitude. Blood was drawn at sea level before the departure for the mountain area, after a week of acclimatization, immediately after the marathon and after a 24-hour recovery period from the run. Cortisol increased after acclimatization and especially after the marathon; it decreased to normal values after recovery. Testosterone decreased after acclimatization, especially after the run; it presented a partial recovery 24 h after the race. Free testosterone did not decrease after acclimatization and presented partial recovery. FTCR could also be useful for monitoring fitness, overtraining and overstrain in strenuous and ultraendurance exercise.

We compared the recently proposed tumor markers CA195, CA242, and CAM43 with a widely used antigen, CA19.9, and a circulating marker of cellular proliferation, TPS, to define their specificity, sensitivity, and cost-benefit ratio. The tumor markers were measured in 41 pancreatic carcinoma patients and in two control groups, the first comprising 19 patients with benign pancreatic diseases, the second comprising 41 healthy blood donors. Sensitivities were 79% for CA19.9, 57% for CA242, 60% for CAM43, 76% for CA195, and 98% for TPS. Specificities calculated for the group with pancreatic diseases were 60% for CA19.9, 84% for CA242, 95% for CAM43, 53% for CA195, and 22% for TPS. Specificities for the blood donor group were 100% for CA19.9, 93% for CA242, 98% for CAM43, 85% for CA195, and 88% for TPS. Positive values for the tumor markers appeared from second stage (Hermreck classification). Metastases, invasion of lymph nodes, and coupling of cancer-associated antigens did not significantly modify marker sensitivity. In pancreatic carcinoma, CA19.9 showed good sensitivity (79%) and high specificity (60-100%). In view of their own advantages (e.g., high specificity of CAM43, high sensitivity of TPS in recurrences) and limits (e.g., low sensitivity of CAM43, very low sensitivity of TPS), the other markers could be used alone or with CA19.9. Two pairs of tumor markers showed high similarity in our study: CA19.9 and CA195, and CAM43 and CA242.

Laboratory diagnostics, a pivotal part of clinical decision making, is no safer than other areas of healthcare, with most errors occurring in the manually intensive preanalytical process. Patient misidentification errors are potentially associated with the worst clinical outcome due to the potential for misdiagnosis and inappropriate therapy. While it is misleadingly assumed that identification errors occur at a low frequency in clinical laboratories, misidentification of general laboratory specimens is around 1% and can produce serious harm to patients, when not promptly detected. This article focuses on this challenging issue, providing an overview on the prevalence and leading causes of identification errors, analyzing the potential adverse consequences, and providing tentative guidelines for detection and prevention based on direct-positive identification, the use of information technology for data entry, automated systems for patient identification and specimen labeling, two or more identifiers during sample collection and delta check technology to identify significant variance of results from historical values. Once misidentification is detected, rejection and recollection is the most suitable approach to manage the specimen.Clin Chem Lab Med 2009;47:143–53.

The development of recombinant DNA technology has allowed the study of the molecular pathology of inherited diseases in man. Two main molecular approaches are employed: direct study for detection of molecular defects and indirect detection by linkage analysis. A variety of new technologies and their applications have provided a powerful new tool in the diagnosis of inherited diseases.

The new selective access analysis system BM/Hitachi 917 was evaluated in an international multicentre study, mainly according to the ECCLS protocol for the evaluation of analysers in clinical chemistry. Forty-three different analytes, covering 56 different methods enzymes, substrates, electrolytes, specific proteins, drugs and urine applications were tested in seven European clinical chemistry laboratories. Additionally, the practicability of the BM/ Hitachi 917 was tested according to a standardized questionnaire. Within-run CVs (median of 3 days) for enzymes, substrates and electrolytes were

Prevention of medical errors is a major goal of healthcare, though healthcare workers themselves have not yet fully accepted or implemented reliable models of system error, and neither has the public. While there is widespread perception that most medical errors arise from an inappropriate or delayed clinical management, the issue of laboratory errors is receiving a great deal of attention due to their impact on the quality and efficiency of laboratory performances and patient safety. Haemolytic specimens are a frequent occurrence in clinical laboratories, and prevalence can be as high as 3.3% of all of the routine samples, accounting for up to 40%-70% of all unsuitable specimens identified, nearly five times higher than other causes, such as insufficient, incorrect and clotted samples. This article focuses on this challenging issue, providing an overview on prevalence and leading causes of in vivo and in vitro haemolysis, and tentative guidelines on identification and management of haemolytic samples in clinical laboratories. This strategy includes continuous education of healthcare personnel, systematic detection/quantification of haemolysis in any sample, immediate clinicians warning on the probability of in vivo haemolysis, registration of non-conformity, completing of tests unaffected by haemolysis and request of a second specimen for those potentially affected.

A new type of interference of cryoglobulins on hemocytometric tests is described. The precipitation of temperature-dependent proteins produced a pseudolymphocytosis on a three-part differential leukocyte count of Coulter S-Plus VI, whereas unaffected results, identical to the microscopical count, were obtained using the cytometer Coulter VCS. The laboratory detection of cryoglobulin interference on hematological data is very important in patients with underlying diseases, where the accuracy of absolute and differential leukocyte counts is critical for follow-up. Histograms from the Coulter S-Plus VI can help detect these cases.

Background: An important point in improving laboratory quality is the definition of some indicators to be monitored as measures of a laboratory trend. The continuous observation of these indicators can help to reduce errors and risk of errors, thus enhancing the laboratory outcome. In addition, the standardization of risk evaluation techniques and the definition of a set of indicators can eventually contribute to a benchmarking process in clinical laboratories. Methods: Five Italian hospital laboratories cooperated in a project in which methodologies for process and risk analysis, usually applied in fields other than healthcare (typically aeronautical and transport industries), were adapted and applied to laboratory medicine. The collaboration of a board of experts played a key role in underlining the limits of the proposed techniques and adapting them to the laboratory situation. A detailed process analysis performed in each center was the starting point, followed by risk analysis to evaluate risks and facilitate benchmarking among the participants. Results and conclusions: The techniques applied allowed the formulation of a list of non-conformities that represented risks of errors. The level of risk related to each was quantified and graphically represented for each laboratory to identify the risk area characteristic for each of the centers involved.

Clinical laboratories have undergone major changes due to technological progress and economic pressure. While costs of laboratory testing continue to be the dominant issue within the healthcare service worldwide, quality, effectiveness and impact on outcomes are also emerging as critical value-added features. Five Italian laboratories are therefore promoting a network of excellence by investigating markers of effectiveness of laboratory services and sharing their experience of using them in clinical practice. In the present study we report preliminary data on indicators of quality in all phases of the so-called total testing process, the key to evaluating all phases of the total testing process, including the appropriateness of test requests and data interpretation. Initial findings in evaluating pre-analytical causes of specimen rejection in three different laboratories and the effects of introducing three laboratory clinical guidelines are reported. These data should stimulate debate in the scientific community and encourage more clinical laboratories to use the same indicators to improve clinical effectiveness and clinical outcomes within the healthcare service.

The present chapter describes a microarray technology developed by Nanogen Inc., for the identification of DNA variations based on the use of microelectronics. The NMW 1000 NanoChip Molecular Biology Workstation allows the active deposition and concentration of charged biotinylated molecules on designated test sites. The DNA at each pad is then hybridized with specific oligonucleotide probes, complementary to normal or mutant sequences, that labeled with Cy3 or Cy5 dyes, respectively. The array is imaged, and fluorescence signals are scanned, monitored, and quantified by highly developed, digital image-processing procedures. The experimental steps to be performed for the development and execution of a microchip assay are described. Attention is focused on the fundamental aspects of probe design, and guidelines and useful suggestions are given. Protocols for sample preparation, addressing, reporting, and data analysis are also detailed.

The present chapter describes a microarray technology developed by Nanogen Inc., for the identification of DNA variations based on the use of microelectronics. The NMW 1000 NanoChip Molecular Biology Workstation allows the active deposition and concentration of charged biotinylated molecules on designated test sites. The DNA at each pad is then hybridized with specific oligonucleotide probes, complementary to normal or mutant sequences, that labeled with Cy3 or Cy5 dyes, respectively. The array is imaged, and fluorescence signals are scanned, monitored, and quantified by highly developed, digital image-processing procedures. The experimental steps to be performed for the development and execution of a microchip assay are described. Attention is focused on the fundamental aspects of probe design, and guidelines and useful suggestions are given. Protocols for sample preparation, addressing, reporting, and data analysis are also detailed.

Molecular diagnostics is being revolutionized by the completion of the human genome project and by the development of highly advanced technologies for DNA testing. One of the most important challenges is the introduction of high throughput systems such as DNA chips into diagnostic laboratories. DNA microchips are small devices permitting rapid analysis of genetic information, exploiting miniaturization of all components and automation of operational procedures. The most important biochip applications include gene expression and genetic variation identification and both may improve human molecular diagnostics. Here we review several approaches developed to allow rapid detection of many single nucleotide polymorphisms and mutations in large population samples. Among these, the use of microelectronics seems to best fit with the needs of molecular diagnostics.

Background: The problem of medical errors has recently received a great deal of attention, which will probably increase. In this minireview, we focus on this issue in the fields of laboratory medicine and blood transfusion.Methods: We conducted several MEDLINE queries and searched the literature by hand. Searches were limited to the last 8 years to identify results that were not biased by obsolete technology. In addition, data on the frequency and type of preanalytical errors in our institution were collected.Results: Our search revealed large heterogeneity in study designs and quality on this topic as well as relatively few available data and the lack of a shared definition of “laboratory error” (also referred to as “blunder”, “mistake”, “problem”, or “defect”). Despite these limitations, there was considerable concordance on the distribution of errors throughout the laboratory working process: most occurred in the pre- or postanalytical phases, whereas a minority (13–32% according to the studies) occurred in the analytical portion. The reported frequency of errors was related to how they were identified: when a careful process analysis was performed, substantially more errors were discovered than when studies relied on complaints or report of near accidents.Conclusions: The large heterogeneity of literature on laboratory errors together with the prevalence of evidence that most errors occur in the preanalytical phase suggest the implementation of a more rigorous methodology for error detection and classification and the adoption of proper technologies for error reduction. Clinical audits should be used as a tool to detect errors caused by organizational problems outside the laboratory.

The Immediate Response Mobile Analyzer (IRMA) is a selective and portable point-of-care testing (POCT) blood gas, electrolyte and hematocrit (Hct) analyzer. The overall analytical performance was evaluated in a two-center study involving two Italian hospital laboratories, following the guidelines suggested by the manufacturer (based on the NCCLS protocol), after a preliminary evaluation of their formal validity. The IRMA was compared to the analyzers used in the routine laboratory as reference. The considered parameters were pH, pO2, pCO2, Na+, K+, ionized calcium and Hct. When using the aqueous quality control material provided by the manufacturer most of the parameters showed good precision, with the exception of pCO2 and pO2 that showed high CVs on two of the three levels of the aqueous control. We could demonstrate that this imprecision was material-related and was reduced when using a different material (blood equilibrated by tonometry). With tonometred blood for pO2 and pCO2 and the aqueous material for the remaining parameters the CVs were all below 5%, ranging from 0.08% to 2.8%. The IRMA results correlated adequately with the comparison instruments, with the exception of sodium and ionized calcium where contradictory results were obtained in the two centers.

The new trends in immunochemistry related to the replacement of radioisotopic labels with non-radioactive labels are presented. Immunoenzymatic, fluorescent and chemiluminescent techniques are described in terms of their basic principles and their most common applications. The advantages of computer-controlled calibration are also discussed.

Diabetes has been claimed to be a risk factor for pancreatic carcinoma, but it is probably a consequence of gland invasion from the neoplastic tissue. A link between diabetes and pancreatic carcinoma was suggested by means of biochemical markers of the diseases, namely glycated hemoglobin and CA19.9. Moreover, CA19.9 was proposed as a sensitive and useful marker of the severity of exocrine damage in diabetes, since the mucin decreased when metabolic compensation improved. We examined 64 diabetic patients (36 insulin dependent, 16 non insulin dependent, 12 treated with diet) by measuring CA19.9 using two different immunometric methods and glycemia and glycated hemoglobin. We observed that a correlation between CA19.9 and biochemical markers of metabolic compensation of diabetes was inexistent and no differences between insulin dependent and non insulin dependent patients were found. A high concentration of CA19.9 in a diabetic patient should be interpreted and evaluated in the same manner as for a non diabetic patient.

Although there are various descriptive reports concerning exercise-induced gastrointestinal distress, the role of gastrointestinal hormones and/or enzymes is not definitively established. In this study we investigated the behaviour of pepsinogens (PCI and PGII) after an endurance race performed at an altitude of 4,300 m by 13 well-trained marathon runners, with the aim to establish their interrelationship with gastrointestinal distress and with the modifications of gastrin and cortisol. The athletes showed a significant rise in gastrin (p < 0.01) and in cortisol (p < 0.01) and a significant decrease in PGI (p < 0.01) and PGII (p

Discrepancies among different methods for assaying human growth hormone have been described in various studies. The two major sources of discordant results are the heterogeneity of the antibodies and the different standardization bases used by the assay manufacturers. We propose standardizing assays with 22-kDa biosynthetic monomer human growth hormone diluted with the diluents supplied by the kit manufacturers. In a study of two monoclonal immunoradiometric assays (Hybritech, specific for the 22-kDa monomer; Sorin, recognizing also a 20-kDa variant hormone), standardization with 22-kDa monomer human growth hormone reduced by 63% the differences in results for 44 serum samples from children. The use of 22-kDa human growth hormone as a common standard, highly pure and easily available in large quantities, could help limit the interpretative problems in growth diagnostics.

We Studied total testosterone, sex hormone binding globulin, and free testosterone in four males presenting an electrophoretically slowmoving genetic variant of albumin, the alloalbumin Catania. Free testosterone levels were lower in these cases, found in a year of observation, than those expected for the ages. This finding, which is not related to any disease and constantly not recognized in other males with various genetic variants, should induce consideration of a probable difference of the genetic variant in hormone binding. © 1992 Wiley-Liss, Inc.

A new tumor marker, tumor-associated trypsin inhibitor (TATI), was studied in 5 patients who received successful kidney or pancreas grafts and in 30 subjects with antibodies against human immunodeficiency virus. Serum TATI concentrations were very high during the four first days after transplantation. Thereafter the serum levels decreased when the peptide was eliminated through the kidney. Consequently, the urine values were very high. The TATI concentrations of HIV positive subjects were compared with serum levels of HIV antigen and antibody, by Western blotting and determination of peripheral T-lymphocyte subpopulations. The occurrence of high concentrations of TATI in some HIV positive subjects and especially in AIDS patients, suggests that TATI could be useful in exploring physiopathological aspects of severe immunodeficiencies even if TATI levels were not correlated with the commonly used markers of the immune system status. The increased levels of TATI in immunological disorders suggests its possible use in assessing the immune response against cancer.

The concentrations of tumor-associated trypsin inhibitor (TATI) in the seminal plasma of infertile males was studied. The TATI levels in seminal plasma were not correlated with either sperm count or ejaculate volume. High levels were observed in some men with unexplained infertility and high or normal sperm counts, whereas normal levels were observed in males with antisperm antibodies. The concentrations in seminal plasma were stable in the same subjects. These results suggest that TATI may be an important marker of reproductive pathology in men.

A clinical laboratory evaluation was conducted on the Clinitek Auto 2000, the Super Aution Analyzer and the Urotron RL9 for the determination of glucose, protein, pH, blood, ketone-bodies and bilirubin.Precision of the systems was tested using three commercial control urine materials, and reported as the percentage of times the instrument repeats a certain value. Good repeatability was obtained with all the instruments.Accuracy of the systems was evaluated by comparison with quantitative procedures, and to check agreement between methods yielding semi-quantitative and quantitative results, ranges of acceptability were defined, based on the criteria reported in a previous paper [2]. It was then found that 87.5 to 98.9% of results from the Urotron RL9 and the Clinitek Auto 2000 were acceptable. With the Super Aution Analyzer the level of agreement was apparently lower because of the higher number of concentration steps used by this instrument.

Two automatic coagulometers--ACL 810 (Instrumentation Laboratory), a laser-nephelometric centrifugal analyzer, and KoaguLab 40 A (Ortho Diagnostics), an optical automatic coagulometer--were compared with the manual tilt-tube method for the performance of prothrombin time (PT). Seven ISI- (International Sensitivity Index) calibrated commercial thromboplastin reagents were used for duplicate determinations in 30 normal subjects, 30 patients with liver disease, and 30 patients receiving stabilized oral anticoagulation. Clotting times were longer with the manual method than with ACL 810 and, to a lesser extent, with KoaguLab 40 A. Average imprecision of duplicate determinations (CV) was less than 1% with ACL 810; KoaguLab 40 A and the manual method had similarly higher imprecisions (2.8% and 2.7%). Differences in origin and slope of the regression curves of clotting times obtained with the coagulometers over the tilt-tube method were observed with all the reagents tested. Transformation of clotting times to PT ratios did not eliminate the bias resulting from the different clot-detection methods. A higher percentage of patients with liver disease had abnormal PT ratios when their plasma was tested with the coagulometers than with the manual method. Transformation of PT ratios to International Normalized Ratios effectively eliminated the bias resulting from the different thromboplastin reagents but had no effect on the bias resulting from the different clot-detection methods. A significant proportion of patients appeared excessively anticoagulated (INR greater than 4.5) with the coagulometers but not with the manual method. These results highlight the need for standardization of both instrumentations and reagents to improve monitoring of oral anticoagulant treatment.

E stata studiata l’attivita α-glucosidasica nel siero di soggetti normali, di pazienti con anuria acuta e di altri pazienti con lesioni renali primitive o secondarie. In tutti i casi con anuria acuta, l’enzima e presente nel sangue, talora a livelli elevati, mentre negli altri casi studiati esso e assente o presente a bassi livelli. E stata esclusa la possibilite che l’assenza dell’attivita enzimatica sia dovuta alia presenza nel siero di inibitori. La curva di pH dell’enzima ematico e risultata sovrapponibile a quella dell’enzima urinario. Vengono discussi l’origine renale dell’enzima sierico e il meccanismo del suo passaggio nel sangue.

L’escrezione con l’urina di α-glucosidasi, contenuta nelle cellule tubulari renali, e un’espressione dell’intensita della lisi di tali elementi. La determinazione quantitativa di tale enzima e un mezzo molto sensibile per rivelare alterazioni litiche. Un confronto tra enzimuria e tipo di proteinuria ha dimostrato che non vi e una correlazione costante tra entita della enzimuria e quadro di proteinuria tubulare. I due indici sono quindi espressione di due diversi tipi di alterazione del tubulo, che possono o meno sovrapporsi ed hanno quindi significato complementare. In particolare, la determinazione dell’α-glucosidasi, per la sua elevata sensibilita, puo evidenziare lesioni tubulari, anche quando non sono sufficientemente intense per determinare il danno funzionale di alterato riassorbimento, espresso dal quadro di proteinuria tubulare.

The phenomenon of in vitro platelet clumping and consequent pseudothrombocytopaenia in the presence of EDTA has been studied in 33,623 subjects referring to a general hospital in a 1-year period. The observed frequency was 0.13%. EDTA-dependent pseudothrombocytopaenia (PTP) was suspected when a routine blood counting by the Coulter S-Plus IV/D showed a peculiar leucocyte histogram and pseudoleucocytosis. Confirmation was obtained by the manual count and by the finding of platelet aggregates in a stained blood smear. EDTA-dependent PTP was diagnosed when the platelet number and the morphological examination of blood anticoagulated with sodium citrate from the same patient were normal. EDTA-dependent PTP was found in 23 subjects aged from 19 to 79 years (0.068% of the study population): 17 were patients suffering from miscellaneous diseases, while six were apparently healthy. As a rule, platelet clumping was evident within 60 minutes from blood collection, but a longer latency (2-3 h) was observed in a few cases. EDTA-dependent PTP is a rare, but misleading phenomenon, the recognition of which is important in order to avoid expensive and potentially harmful procedures.

A multicentre evaluation of the Monarch centrifugal analyser is reported. Precision, linearity and accuracy were assessed by comparison with routine methods. Calibration stability, photometric and dispensing accuracy, and carry-over related to samples and reagents were also evaluated. The overall performance of the instrument was good, showing an excellent photometric and dispensing accuracy, absence of sample-dependent carry-over, and almost negligible reagent carry-over. Good precision, linearity and correlation with routine methods were found for the parameters tested. The instrument is reliable and is now used as the routine clinical chemistry analyser in two of the three laboratories taking part in the evaluation.

Summary Cryoglobulins may produce interference in results from electronic particle counters. Depending on their size, cold-precipitable globulin crystals can be counted as leucocytes and/or platelets. The Coulter Counter model S-Plus IV/D permits detection of this interference and its associated spurious counts by producing a characteristic WBC histogram accompanied by a leucocyte ‘flag’. Using this instrument over a 1-year period, 10 cases of cryoglobulinemia were detected, four from patients with lymphoproliferative disease and one from a patient with autoimmune disease. The remaining five were classified as essential mixed cryoglobulinemia. The reproducibility of this instrument anomaly permits identification of the presence of cryoglobulins.

The preparation and evaluation of ethylene glycol-stabilized haemolysates for use as control material for the assay of glycated haemoglobins is described. These haemolysates were prepared from normal and diabetic blood samples by following the procedure normally used to purify human haemoglobin, with the addition of dialysis to remove glucose from the labile fractions, and dilution with ethylene glycol. All the haemoglobin fractions were converted into the carbon monoxide form to increase their stability and were stored under different conditions. During a 10 month period of storage at -20 degrees C no significant change in the glycated haemoglobins level was observed.