Correlation between sodium, potassium, hemoglobin, hematocrit, and glucose values as measured by a laboratory autoanalyzer and a blood gas analyzer.

INTRODUCTION: Blood gas analyzers can be alternatives to laboratory autoanalyzers for obtaining test results in just a few minutes. We aimed to find out whether the results from blood gas analyzers are reliable when compared to results of core laboratory autoanalyzers. MATERIALS AND METHODS: This retrospective, single-centered study examined the electronic records of patients admitted to the emergency department of a tertiary care teaching hospital between May 2014 and December 2017. Excluded from the study were patients under 18 years old, those lacking data, those who had any treatment before the laboratory tests, those whose venous gas results were reported more than 30 minutes after the blood sample was taken and for whom any of the laboratory tests were performed at a different time, and recurrent laboratory results from a single patient. RESULTS: Laboratory results were analyzed from a total of 31,060 patients. The correlation coefficients for sodium, potassium, hemoglobin, hematocrit, and glucose levels measured by a blood gas analyzer and a laboratory autoanalyzer were 0.725, 0.593, 0.982, 0.958, and 0.984, respectively; however, there were no good, acceptable agreement limits for any of the parameters. In addition, these results did not change according to the different pH stages (acidosis, normal pH and alkalosis). CONCLUSION: The two types of measurements showed a moderate correlation for sodium and potassium levels and a strong correlation for glucose, hemoglobin, and hematocrit levels, but none of the levels had acceptable agreement limits. Clinicians should be aware of the limitations of blood gas analyzer results.

Performance characteristics of four automated natriuretic peptide assays.

Measurement of circulating B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) can identify patients with heart failure and guide therapy. The limit of detection, linearity, imprecision, method comparison, analytic concordance, and reference intervals of the Access 2 BNP (Biosite, San Diego, CA), ADVIA Centaur BNP (Bayer Diagnostics, Tarrytown, NY), AxSYM BNP (Abbott Diagnostics, Abbott Park, IL), and E170 NT-proBNP (Roche Diagnostics, Indianapolis, IN) methods were evaluated. The Triage meter BNP assay (Biosite) was the comparison method. Imprecision testing showed total coefficients of variation of 4.1%, 4.4%, 5.5%, and 0.8% for the Access 2, ADVIA Centaur, AxSYM, and E170, respectively. Relative to the Triage meter, method comparison revealed a slope of 0.96 and r = 0.95, a slope of 0.77 and r = 0.92, a slope of 1.13 and r = 0.94, and a slope of 8.8 and r = 0.80 for the Access 2, ADVIA Centaur, AxSYM, and E170, respectively. Overall analytic concordance values with the Triage meter were 95.9%, 92.9%, 92.4%, and 84.3% for the Access 2, ADVIA Centaur, AxSYM, and E170, respectively. All automated natriuretic peptide methods showed acceptable analytic performance.

Automated procedures for the quantitation of protein.

An entirely automated 96-well microplate-based system to perform procedures for the measurement of protein is described. This single instrument system utilizes a series of computer-controlled mechanical subsystems to move the plate, control incubations and dispense samples or reagents in order to perform the assay. This system allows the investigator to reproducibly perform these protein assays on large numbers of biological samples with minimal effort.

A high-sensitivity electrochemiluminescence-based detection system for automated PCR product quantitation.

A high-sensitivity nonisotopic system has been developed for post-PCR product detection. The probe-based detection system exploits a chemiluminescent reaction that takes place on the electrode surface in an electrochemical cell. The detection system incorporates a biotin-streptavidin capture reaction onto a solid support that permits fast post-PCR product detection at the attomole level. The system precision is within 5% relative standard deviation over a linear dynamic range of greater than three orders of magnitude. In this paper, the principles and features of the electrochemiluminescent-based detection system, together with its application to PCR product quantitation, are described in detail.

Accuracy of automated DNA sequencing: a multi-laboratory comparison of sequencing results.

A double-stranded (ds)DNA template of "unknown" sequence was distributed to approximately 80 core DNA sequencing laboratories by the Association of Biomolecular Resource Facilities (ABRF) for automated DNA sequence analysis. Forty-four different facilities responded with 83 usable sequence submissions. These sequences were grouped by both sequencing protocol (dye-primer or dye-terminator) and whether manually edited or not. The sequences were aligned with the known sequence, and the number of correct base calls, insertions, deletions, no-calls and miscalls were determined for each group. The dye-primer sequencing protocol provided the longest and most accurate sequence. The edited dye-primer data were > 95% accurate out to 400-450 bp, while the edited dye-terminator data could call only 300-350 bases at this accuracy. However, 75% of the laboratories in this sampling preferred the dye-terminator protocol, presumably because of its versatility and convenience. Laboratories that manually edited the automatically called data were able to obtain an additional 100 bases of good sequence when the dye-primer protocol was used. Surprisingly though, editing of dye-terminator results did not increase the amount of good sequence, although the dye-terminator protocol had a superior base-calling ability within the first 100 bases of called sequence.

Inefficacy of moving average algorithm as principal quality control procedure on Technicon System H6000.

Bull's algorithm, in its "revisited" formulation, represents one of the main quality control (QC) procedures in several multichannel automatic hematological analyzers. Its efficacy, however, is reduced in the theoretical event that red blood cells (RBC) and hemoglobin (Hgb) undergo a concomitant analytical drift while mean corpuscular volume (MCV) remains unaffected, so that a null effect is registered on the related erythrocytic indices: mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC). This particular phenomenon has been observed on the Technicon System H6000. Routine daily work was kept in control through the use of commercial controls and fresh blood samples: a reproducible positive drift of two directly measured erythrocytic parameters (RBC and Hgb) and of the calculated hematocrit (Hct) was observed proportional to the time of continuous use of the instrument. The usefulness of Bull's QC scheme was greatly reduced: it failed to detect "out of control" situation in 38%, 15%, and 13% of cases in the monitoring of MCV, MCH, and MCHC, respectively, when compared with the traditional 2 SD limits on QC samples.

A field evaluation of the Coulter STKS.

The performance of the Coulter STKS (Coulter, Hialeah, FL) was evaluated in a busy computerized teaching hospital laboratory. The STKS was compared with a Coulter S Plus IV and manually performed 400 white blood-cell differentials. The measured blood-count parameters (i.e., white blood cells [WBCs], red blood cells [RBCs], hemoglobulin [Hb], mean corpuscular volume [MCV], and platelets [PLTs]), compared very well between the two aperture impedance-based systems; precision, linearity, and lack of carryover were excellent. The STKS WBC differential (DIFF), derived from a combination of aperture impedance, aperture conductance, and laser light scatter, also was precise; linear and carryover were insignificant. The DIFFs (n = 424) compared well to the manual WBC differentials, with r values of 0.97, 0.97, 0.73, and 0.86 for neutrophils, lymphocytes, monocytes, and eosinophils, respectively. The DIFF and Suspect Flagging system produced 6.2% false negatives and 2.6% false positives when compared with the manual technique. These were further investigated and discussed. STKS DIFFs were stable for 18 to 24 hours in normal samples anticoagulated with K2EDTA and stored at 20 degrees C prior to analysis. Storage in the same anticoagulant at 4 degrees C and immediate aspiration preserved the DIFF analysis for considerably longer than 24 hours. These performance characteristics make the STKS a significant advancement in automated hematology.

The automated CBC. A current perspective.

CBC traditionally stands for complete blood count. It represents a profile of tests rather than a single test, and over the years it has been given several names, including hemogram, Coulter profile, blood cell profile, and hematology profile. The number and type of tests included in the profile has also changed over time and among laboratories, depending primarily upon capabilities of the automated analyzers used to perform the profile test.

The automated white blood cell differential. A current perspective.

The white blood cell differential count represents a major portion of the workload in the hematology laboratory. The traditional procedure whereby a technologist examines a Romanowsky-stained blood film and classifies 100 cells is both labor intensive and imprecise. To significantly improve the precision, the technologist would have to count and classify at least 1000 cells, which is obviously impractical in terms of time and efficiency. Until the availability of the automated hematology instruments, it was not possible to obtain a differential count that could be regarded as statistically significant. Automation is therefore necessary and desirable for both economic and clinical reasons. Automation can also provide a number of instrument-derived parameters tha have attained diagnostic significance in their own right. Analytic and technologic advances have occurred with every generation of hematology instruments. As the means of analysis becomes more sophisticated, additional categories of cells may be expected to be classified, and current categories may be more accurately and precisely defined. It is hoped this will lead to even greater clinical utility, as well as provide quality assurance and assessment methods that need to be developed similar to other procedures in the clinical laboratory.

Selection of an optimal combination of decision criteria for the internal quality control in an automatic analyzer.

After some years using an automatic analyser model Hitachi 705, we faced the task of selecting a reasonable combination of statistical procedures for internal quality control in order to use it in a computer program, by means of which, one could apply all the decision criteria in a rapid and automatic manner. As a result of the first 3 years of work, an algorithm was adopted that includes the multirule procedure originally proposed by Westgard, but with three main differences: (1) All the control rules are always applied; (2) the 4(1S) and 10x control rules are used as criteria for warning or caution but not for run rejection; and (3) the control limits are recalculated daily using all the accumulated control results (just the accepted values). The 2(2S), 4(1S) and 10x rules are applied first across materials (considering consecutive observations in different control materials), and then within materials (for consecutive observations on the same control material). The program not only has permitted us to improve our capacity for error detection, but it has also permitted the reduction of run rejections making an important decrease in costs possible and a significant improvement in quality.

Automation of thyroid function testing.

This article discusses the automation of thyroid function testing. The needs for automation are included in the introduction. The issues concerning automation of immunoassay are discussed, including homogeneous or heterogeneous immunoassay, competitive or immunometric assay, reagent stability, data management, sample management, signal detection, and the disadvantages of automation. Individual immunoassay systems are summarized with a table outlining the key features. Both technical and clinical performance of automated thyroid function testing are described. The article ends with a discussion of the future trends of automated immunoassay testing.

Comparison of the Abbott Cell Dyn 3000 SL and the Coulter STKS hematology analyzers.

A side by side comparison of the Cell Dyn 3000 SL and Coulter STKS using identical samples was performed over a four month period in the Clinical Hematology Laboratory at the University of Cincinnati Medical Center. A total of 444 samples comprised of 114 sophomore medical students and 330 randomly selected clinical patients were compared in 20 hemogram parameters, and the ability of each instrument to generate differential suspect flags was analyzed. Correlation coefficients for leukocytes, erythrocytes, hemoglobin, hematocrit, and platelets were 0.99. Correlation coefficients for the Cell Dyn and STKS compared with a 600 cell manual differential were 0.98 and 0.89 for neutrophils, 0.96 and 0.87 for lymphocytes, and 0.72 and 0.48 for monocytes, respectively. Both instruments demonstrated high precision and accuracy by internal and external quality control standards. Each analyzer exhibited strength as a screening instrument for abnormal cell populations. The Coulter STKS had overall sensitivity of 75%, specificity of 94%, 25% false negatives, and 6% false positives. Sensitivity, specificity, false negative and positive rates for the Cell Dyn 3000 SL were 68%, 92%, 32%, and 8%, respectively. Based upon this extensive side by side comparison using an identical sample population, it has been concluded that although statistically significant systematic bias (p < 0.05) exists between the two instruments, both analyzers can adequately support the needs of the clinical hematology laboratory.

[Automated blood cell measurements: a comparison between the Bayer H2 and the Abbott Cell-Dyn 3500]. / L'esame emocromocitometrico in automazione: confronto tra Bayer H2 e Abbott Cell-Dyn 3500.

INTRODUCTION: We have compared two hematologic analyzers, H2 (Bayer) and CELL DYN 3500 (Abbott). The protocol we used was able to evaluate the overall analytical quality, the effect of aging of the sample on the measured parameters, the quality of leucocytes differential count. Number and quality of information supplied for each sample by both analyzers were then taken in account. RESULTS: Excellent correlation for all measured parameters was found: only monocytes were, albeit modestly, overestimated by CELL DYN 3500 compared to H2. Ageing of sample and temperature of storage had a marked effect on CELL DYN's measurements, resulting in impaired recognition and classification of leucocytes, while the results for the other parameters were acceptable. Comparative evaluation of the differential count of leucocytes was made between the results of both analyzers and microscopic examination. While specificity, predictive value of negative results and quantity of false negative results were practically the same, sensitivity, predictive value of positive results and quantity of false positive results were better for H2 as compared to CELL DYN (87.1% vs 78.1%, 79.4% vs 65.8, 7 vs 13, respectively). The clinical utility of supplementary informations (alarms, flags, cytograms, etc.) yielded by the analyzers was relevant for H2 regarding the erythrocytes cytograms, for CELL-DYN 3500 regarding the application of the extended lyse program for lytic resistant RBCs and of the Vet Package. CONCLUSIONS: CELL DYN 3500 performance have on the whole confirmed the producer's claims, being of reliable use in the haematological screening on account of its simplicity and more than good overall analytical quality.

Characterization, standardization and experiences with KONE ISE for Mg2+.

The principles of a fully automated potentiometric determination of ionized magnesium in human blood serum are presented. By incorporating a magnesium selective electrode, into a commercially available six channel electrolyte analyzer (Microlyte 6, KONE Instruments, Finland), determination of the biologically-active, ionized fraction of magnesium has been made possible. In this paper, the analytical performance of the measurement system is presented and determination of ionized magnesium in real patient samples is discussed with special attention to the significance of this new parameter.

Clinical findings on human blood with the KONE ISE for Mg2+.

Ionized magnesium was measured using a clinical analyzer MICROLYTE 6 (KONE, Finland). Total magnesium was measured colorimetrically. The influence of anion-ligands on Mg-ISE responses was investigated. Ionized magnesium (iMg) concentration changes with pH were made to observe the accuracy of results. The dependence of iMg and iCa on heparin (used as anticoagulant in plasma samples) was made. Less than 40 units per 1 ml of blood decreased the concentration of iMg and iCa less than 1.5%. The range of iMg and total Mg in serum and plasma of healthy and ill adults (short bowel syndrome, myocardial infarct) was investigated and compared to each other. In both illnesses, the concentration of ionized and/or total magnesium is significantly different from the range for healthy people. The range of iMg and total Mg as well as the percentage of iMg against total Mg seem to be specific for given illness. The range of iMg and total Mg in blood serum of healthy children was also investigated.

[The amino acid composition of the antigenic structures of the human heart conduction system]. / Aminokislotnyi sostav antigennykh struktur provodiashchei sistemy serdtsa cheloveka.

Amino acid composition of proteins from antigen preparations of the human heart conduction system has been studied. Differences in amino acid composition and relative affinity of the structure of two groups were found: between the sinus and atrioventricular nodes, the His bundle and contractile myocardium.

[Development and analytical validation according COFRAC recommendations of pyruvate and ketone body assay on open automated analyser]. / Mise au point et validation en portée B selon les recommandations du Cofrac d'un dosage de pyruvate et de corps cétoniques sur un automate ouvert.

Measurements of pyruvate and ketones bodies (acetoacetate and 3-hydroxybutyrate) are essential to the investigation of intermediary metabolism. Indeed, their blood levels reflect energy balance influenced by nutritional status. This balance can be disturbed in certain diseases such as diabetes and some inherited metabolic disorders. We have developed methods for assays on open automated biochemistry analyser, Konelab 20 XT (ThermoFischer, Whaltham USA), using kits marketed by Sobioda (Montbonnot, France) for pyruvate and Wako Chemicals GmbH (Neuss, Germany) for ketones, on deproteinised blood sample. We have validated the performance of these three quantitative methods using NF EN ISO 15189 (range B) standard criteria. We obtain satisfactory results concerning fidelity (precision measured as within and between batch CVs are respectively less than 7% and less than 6%), measuring ranges (from 7.7 to 228 µmol/L for pyruvate and from 22.6 to 650 µM for total ketone bodies), accuracy (10.4 µmol/L in physiological range for pyruvate and 7.1 µmol/L for 3-hydroxybutyrate) and comparing methods (versus manual assay with spectrophotometry on Uvikon XL). Establishment of reference ranges (35 to 74 µmol/L for pyruvate, less than 100 µM for 3-hydroxybutyrate and less than 44 µmol/L for acetoacetate) and reagents stability study (up to 12 weeks if frozen) have enabled us to finalize method validation and to add these assays to our routine laboratory repertoire.

An automated analyzer provides clinically concordant results to manual back titration for quantitation of bicarbonate in pancreatic juice.

OBJECTIVES: Secretin pancreatic function tests play an important role in the diagnosis of chronic pancreatitis. Back titration is the standard method for measurement of bicarbonate in pancreatic juice but is time consuming and manually performed. Use of an autoanalyzer for this purpose is not validated. METHODS: Bicarbonate concentrations in secretin-stimulated pancreatic juice specimens were quantitated by manual back titration, a clinical chemistry autoanalyzer (automated bicarbonate, Roche Cobas c501, Roche Diagnostics, Indianapolis, Ind), and a blood gas analyzer (calculated bicarbonate, GEM 3000, Instrumentation Laboratories, Bedford, Mass). Kappa statistic analysis, Bland-Altman analysis, and Lin concordance correlation coefficients were calculated. RESULTS: Ninety specimens from 31 subjects were included. Using a bicarbonate concentration of 80 mEq/L as a cutoff value, there was poor agreement between back titration and calculated bicarbonate (κ = 0.188); however, only 1 specimen showed discrepancy between back titration and automated bicarbonate (κ = 0.977). The limit of agreement between the back titration and automated bicarbonate was -9.0 to + 8.3 mEq/L. The Lin concordance correlation coefficient between the 2 methods was 0.931 (P < 0.001). CONCLUSIONS: There is strong concordance between manual back titration and chemistry autoanalyzer methods for measurement of bicarbonate concentrations in pancreatic juice. Autoanalyzers may replace back titration for this purpose. Blood gas analyzers are unsuitable.