Analytical validation of a point-of-care test and an automated immunoturbidimetric assay for the measurement of canine C-reactive protein in serum.

C-reactive protein (CRP) is an acute phase protein, which is used to evaluate and monitor the response of the innate immune system to a variety of inflammatory processes in the dog. The purpose of this study was to analytically validate a point-of-care assay (IDEXX Catalyst CRP Test) and an immunoturbidimetric assay (Gentian Canine CRP Immunoassay) for the measurement of serum CRP concentrations in dogs. These 2 assays (Catalyst, Gentian) were compared to a previously validated enzyme-linked immunosorbent assay (Tridelta Development EIA Canine CRP Assay). Linearity, precision, reproducibility, and accuracy were assessed using leftover serum samples. Agreement between assays was assessed using leftover serum samples and serum from clinically healthy dogs. Observed to expected ratios (O/E) for dilutional parallelism were 83.9 to 163.1% and 108.3 to 160.6% for the Catalyst and the Gentian assays, respectively. Coefficients of variation for intra-assay variability ranged from 6.4 to 9.5% for the Catalyst assay and 1.5 to 2.6% for the Gentian assay. Coefficients of variation for inter-assay variability ranged from 3.8 to 18.2% for the Catalyst assay and 4.5 to 5.8% for the Gentian assay. The mean O/E for recovery were 97.9% and 98.5% for the Catalyst and Gentian assays, respectively. Correlations between assays were as follows: Catalyst and Tridelta (R 2 = 0.76), Gentian and Tridelta (R 2 = 0.79), and Catalyst and Gentian (R 2 = 0.98). The Catalyst and Gentian assays are both acceptable for measuring CRP in dog serum, but their results are not directly comparable with the Tridelta assay.

La protéine C réactive (CRP) est une protéine de phase aiguë, qui est utilisée pour évaluer et surveiller la réponse du système immunitaire inné à une variété de processus inflammatoires chez le chien. Le but de cette étude était de valider analytiquement un test au point de service (test IDEXX Catalyst CRP) et un test immunoturbidimétrique (Gentian Canine CRP Immunoassay) pour la mesure des concentrations sériques de CRP chez le chien. Ces deux tests (Catalyst, Gentian) ont été comparés à un test immuno-enzymatique précédemment validé (Tridelta Development EIA Canine CRP Assay). La linéarité, la précision, la reproductibilité et l'exactitude ont été évaluées à l'aide d'échantillons de sérum restants. La concordance entre les tests a été évaluée à l'aide d'échantillons de sérum restants et de sérum provenant de chiens cliniquement sains. Les rapports observés/attendus (O/E) pour le parallélisme de dilution étaient de 83,9 à 163,1 % et de 108,3 à 160,6 % pour les tests Catalyst et Gentian, respectivement. Les coefficients de variation pour la variabilité intra-test variaient de 6,4 à 9,5 % pour le test Catalyst et de 1,5 à 2,6 % pour le test Gentian. Les coefficients de variation pour la variabilité inter-test variaient de 3,8 à 18,2 % pour le test Catalyst et de 4,5 à 5,8 % pour le test Gentian. L'O/E moyen pour la récupération était de 97,9 % et de 98,5 % pour les tests Catalyst et Gentian, respectivement. Les corrélations entre les tests étaient les suivantes : Catalyst et Tridelta (R 2 = 0,76), Gentian et Tridelta (R 2 = 0,79) et Catalyst et Gentian (R 2 = 0,98). Les tests Catalyst et Gentian sont tous deux acceptables pour mesurer la CRP dans le sérum de chien, mais leurs résultats ne sont pas directement comparables avec le test Tridelta.(Traduit par Docteur Serge Messier).

Prospective comparison of (1,3)-beta-D-glucan detection using colorimetric and turbidimetric assays for diagnosing invasive fungal disease.

Serum (1→3)-ß-D-glucan (BDG), an pan fungal antigen, is detected in some invasive fungal diseases (IFDs). We compared two commercial kits, the Fungitell assay (FA) (colorimetric) and the Wako assay (WA) (turbidimetric) over a 4-month period to prospectively test 171 patients who mainly had hematological conditions (62%) and experienced episodes (n = 175) of suspected invasive fungal infection. Twenty-three episodes due to BDG-producing fungi were diagnosed (pneumocystosis, n = 12; invasive aspergillosis, n = 5; candidemia, n = 3; invasive fusariosis, n = 2; hepato-splenic candidiasis, n = 1).Both assays provided similar areas under the curves (AUC = 0.9). Using the optimized positivity thresholds (≥120 pg/ml for FA and ≥ 4 pg/ml for WA), the sensitivity and specificity were 81.8% (CI95: 61.5-92.7), 94.8% (90.1-97.3) for FA and 81.8% (61.5-92.7), 95.4% (90.9-97.8) for WA. Negative predictive value was 97.3% (93.3-99.0) for both tests. If the manufacturer's positivity threshold (≥11 pg/ml) was applied, the WA sensitivity decreased to 50%. Among 71 patients with bacterial infections, 21.1% were FA-positive and 5.6% were WA-positive (p < 10-2).The WA performed similarly as compared to the FA with an optimized cutoff value. The WA is a single sample test that is clinically relevant when a prompt therapeutic decision is required. LAY SUMMARY: Serum (1→3)-ß-D-glucan testing is dominated by two kits including Fungitell colorimetric assay (FA) and the Wako turbidimetric assay (WA). We compared them prospectively and observed that they both perform similarly when selecting their optimal threshold (≥120 pg/ml for FA and ≥ 4 pg/ml for WA).

Preparation and characterization of cyclic citrullinated peptide-immobilized latex beads for measurement of anti-citrillinated protein antibody through latex particle-enhanced turbidimetric immunoassay.

The anti-citrillinated protein antibody (ACPA) plays an important role in early diagnosis of rheumatoid arthritis (RA), and is usually detected by using cyclic citrullinated peptide (CCP) as antigen. The ACPA against CCP test is usually performed utilizing enzyme-linked immunosorbent assay (ELISA), but the ELISA is expensive and time-consuming. Here, latex particle-enhanced turbidimetric immunoassay (LTIA) based on CCP-immobilized latex bead was proposed for fast measurements of ACPA of RA patients. CCP-immobilized latex bead was fabricated through three methods, including direct coupling, overall coupling and layer by layer coupling. According to the optimized experiments, layer-by-layer coupling was the best method with advantages of time-saving, simple operation and good repeatability. In addition, a spacer arm of appropriate length between latex beads and CCP could avoid stereoscopic obstacles and make ACPA closer to CCP. The CCP-immobilized latex bead based on layer by layer coupling (CCP-LB-LLC) was used for assembling the homemade kit, which was applied in fast measurements of ACPA through LTIA. The homemade kit possessed a low limit of detection (0.2 U/mL) and an acceptable the batch-to-batch reproducibility. In addition, the homemade kit can be stored at 4 °C for at least one month. When used to detect 20 clinical samples, the results of homemade kit were consistent with commercial ELISA. Furthermore, LTIA based on the homemade kit was simpler and cheaper than ELISA. These results demonstrated that the homemade kit could be useful for diagnosis of RA patients.

A new diagnostic indication device of a biomarker growth differentiation factor 15 for mitochondrial diseases: From laboratory to automated inspection.

Mitochondrial diseases (MDs) are occasionally difficult to diagnose. Growth differentiation factor 15 (GDF15) has been reported as a biomarker useful for not only diagnosing MDs, but also evaluating disease severity and therapeutic efficacy. To enable the measurement of serum GDF15 concentrations at medical institutions, we developed a new latex-enhanced turbidimetric immunoassay (LTIA) as an automated diagnostic indication test for MDs. We also examined the equivalency of specificity and sensitivity in measuring serum GDF15 concentrations between a commercially available enzyme-linked immunosorbent assay (ELISA) kit and a novel LTIA device in patients with MDs, disease controls, and healthy controls. A clinical performance study used a newly developed LTIA device and an existing ELISA kit to measure the concentrations of GDF15 in 35 MD patients, 111 disease controls, and 86 healthy controls. The median (first quartile-third quartile) of serum GDF15 concentrations measured with the LTIA device was significantly higher (P < .001) in MD patients (1389.0 U/mL [869.5-1776.0 U/mL]) than in healthy controls (380.5 U/mL [330.2-471.8 U/mL]); the interquartile ranges did not overlap between MD patients and healthy controls. The areas under the curve in disease and healthy controls were 0.812 (95% confidence interval [CI]: 0.734-0.886) and 0.951 (95% CI: 0.910-0.992), respectively. The automated, high-throughput technology-based LTIA device has definite advantages over the ELISA kit in shorter processing time and lower estimated cost per sample measurement. The LTIA device of GDF15 may be a sufficiently reliable, frontline, diagnostic indicator of individuals with suspected MDs in the general population.

Impact of albumin carbamylation on immunoturbidimetric measurement of urinary albumin.

Urinary albumin is one of the main markers used in clinical practice to assess kidney damage. It is usually measured in laboratories through immunological assays, but these assays may not detect molecules with conformational changes, such as carbamylated albumin/proteins. Therefore, this study aimed to investigate the impact of albumin carbamylation on the measurement of albuminuria by an immunoturbidimetric assay. The addition of the carbamylating agent to PBS buffer and urine pool promoted a lower quantification of albumin measured by the immunoturbidimetric method, indicating that this process may be responsible for an underestimation of the results in clinical practice.

Verification of automated latex-enhanced particle immunoturbidimetric D-Dimer assays on different analytical platforms and comparability of test results.

INTRODUCTION: The aim of the study was the analytical verification of automated latex-enhanced particle immunoturbidimetric (LPIA) D-Dimer assay INNOVANCE D-dimer on Sysmex CS-5100 and Atellica COAG 360 analysers, and HemosIL D-dimer HS500 on ACL TOP 550, as well as the comparison with the enzyme-linked immunofluorescent assay (ELFA) on the miniVidas analyser. MATERIALS AND METHODS: Verification included assessment of within-run and between-run precision, bias, measurement uncertainty (MU), verification of the cut-off, method comparison between all assessed assays, and the reference commercial ELFA VIDAS D-Dimer Exclusion II. RESULTS: Within-run coefficients of variations (CVs) ranged from 1.6% (Atellica COAG 360) to 7.9% (ACL TOP 550), while between-run CVs ranged from 1.7% (Sysmex CS-5100) to 6.9% (Atellica COAG 360). Spearman's rank correlation coefficients were > 0.99 between LPIAs and ≥ 0.93 when comparing ELFA with LPIA. Passing-Bablok regression analysis yielded constant and proportional difference for comparison of ACL TOP 550 with both Sysmex CS-5100 and Atellica COAG360, and for miniVidas with Atellica COAG360. Small proportional difference was found between miniVidas and both Sysmex CS-5100 and ACL TOP 550. Calculated MUs using D-dimer HS 500 calibrator were 12.6% (Sysmex CS-5100) and 15.6% (Atellica COAG 360), while with INNOVANCE D-dimer calibrator 12.0% (Sysmex CS-5100), 10.0% (Atellica COAG 360) and 28.1% (ACL TOP 550). Excellent agreement of results was obtained, with occasional discrepancies near the cut-off. The cut-off (0.5 mg/L FEU) was confirmed. CONCLUSIONS: The obtained results prove satisfactory analytical performance of LPIAs, their high comparability and almost equal discriminatory characteristics, suggesting them as a valid alternative to ELFA.

Detection of immunoglobulin indexes by immunoturbidimetry: patients with chronic hepatitis B.

BACKGROUND: The objective of this study was to explore the clinical effect of immunoglobulin test in patients with chronic hepatitis B. METHODS: Fifty patients with chronic hepatitis B, 50 patients with liver failure and 50 patients with cirrhosis were selected from the Third People's Hospital of Baoji as experimental groups, and 50 healthy people as the control group. The immunoglobulin M (IgM), IgG and IgA levels in serum of the patients were tested by immunoturbidimetry before and after targeted treatment. RESULTS: Before treatment, the level of Ig in patients with hepatitis B, liver failure and cirrhosis were significantly higher than those in normal people; the level of Ig in patients with hepatitis B were significantly lower than those in patients with liver failure and cirrhosis, and the level of Ig in patients in different groups increased significantly as the disease developed. After treatment, the level of Ig in patients in different groups decreased significantly; patients in the experimental group who had good treatment result had significant decrease of Ig level, while patients in the experimental group who had aggravated disease condition had significant increase of Ig level. CONCLUSIONS: Detection of serum Ig level in patients with chronic hepatitis B can effectively help determine the condition of patients before and after treatment, so as to formulate appropriate treatment plan.

Cistatina C: Biomarcador de riesgo cardiovascular en VIH / Cystatin C: Biomarker of cardiovascular risk in HIV

INTRODUCCIÓN: Los pacientes infectados por el virus de la inmunodeficiencia humana (VIH) tienen mayor riesgo cardiovascular (RCV). El desarrollo de enfermedad cardiovascular (ECV) en esta población involucra factores de RCV tradicionales y factores relacionados con la propia infección, como el estado proinflamatorio crónico, la disfunción inmune y el tratamiento antirretroviral recibido. La cistatina C (CC) ha demostrado utilidad para valorar la presencia de factores de RCV y ECV establecida en población general, ancianos y enfermos renales. Analizamos dicha asociación en una población VIH+. MATERIAL Y MÉTODOS: Estudio analítico, observacional, transversal. Se recogieron factores de RCV y presencia de ECV en pacientes VIH+, obteniendo determinación de CC. Se establecieron 2 grupos: grupo1=CC elevada (≥0,95mg/L) y grupo 2=CC normal (<0,95mg/L). RESULTADOS: Se incluyeron 95 pacientes, grupo1=27 (28,4%) y grupo2=68 (71,5%). Un valor de CC≥0,95mg/L se relacionó con la presencia de ECV (p = 0,01); con aumento de medias de circunferencia de cintura (p = 0,05), circunferencia de cuello (p = 0,04), presión arterial sistólica (p = 0,04), presión arterial diastólica (p = 0,01), puntaje al score de riesgo de Framingham (p = 0,03) y puntaje al score de riesgo de Framingham adaptado para VIH (p = 0,01). Después de realizarse análisis multivariado con incorporación de variables con asociación bivariada a ECV, solo CC≥0,95mg/L continuó relacionándose con ECV. CONCLUSIÓN: CC≥0,95mg/L se relacionó de forma independiente con la presencia de ECV. Este punto de corte también se vinculó a mayores niveles de presión arterial y mayor RCV a 10 años calculado por score de Framingham y score adaptado para población VIH

INTRODUCTION: Patients infected with the human immunodeficiency virus (HIV) have a higher cardiovascular risk (CVR). The development of cardiovascular disease (CVD) in this population involves traditional CVR factors and factors related to the infection itself, such as chronic inflammatory status, immune dysfunction, as well as the antiretroviral therapy received. Cystatin C (CC) has shown to be useful in assessing the presence of CVR factors and CVD established in the general population, the elderly population, and patients with chronic kidney disease. An analysis was performed on this association in an HIV positive population (HIV+). MATERIAL AND METHODS: Analytical, observational, cross-sectional study was conducted, and included collecting information about CVR factors and CVD in HIV+, as well as measuring CC. The patients were divided into 2 groups: Group1=high CC (≥0.95mg/L) and Group2=normal CC (<0.95mg/L). RESULTS: A total of 95 patients were included. Group1=27 (28.4%) and Group2=68 (71.5%). A value of CC≥0.95mg/L was related to the presence of CVD (P=.01). It was also related with and an increase in waist circumference (P=.05), neck circumference (P=.04), systolic blood pressure (P=.04), diastolic blood pressure (P=.01), Framingham score (P=.03), and Framingham score adapted for HIV (P=.01). After performing multivariate analysis with incorporation of variables associated with CVD in the bivariate analysis, only CC≥0.95mg/L continued to be related to CVD. CONCLUSION: CC≥0.95mg/L was independently associated with CVD. This cut-off point was also linked to higher levels of blood pressure, and higher CVR at 10 years using the Framingham Score and Framingham Score adapted for HIV population

Identification of and solution for false D-dimer results.

BACKGROUND: Clinically, D-dimer (DD) levels are mainly used to exclude diseases such as deep venous thrombosis (DVT). In clinical testing, DD assays can be subjected to interference that may cause false results, which directly affect the clinical diagnosis. Our hypothesis was that the 95% confidence intervals (CIs) of the fibrin degradation product (FDP)/DD and fibrinogen (Fib)/DD ratios were used to identify these false results and corrected via multiple dilutions. METHODS: In total, 16 776 samples were divided into three groups according to the DD levels detected by Sysmex CS5100 and CA7000: Group A, DD ≥ 2.0 µg/mL fibrinogen equivalent unit (FEU); group B, 0.5 < DD < 2.0 µg/mL FEU; and group C, DD ≤ 0.5 µg/mL FEU. The 95% CIs of the FDP/DD and Fib/DD ratios were calculated. Six abnormal DD results were found according to the 95% CIs. For verification, we performed multiple dilutions, compared the results with those of other instruments, and tested the addition of heterophilic blocking reagent (HBR). RESULTS: The median and 95% CI of the FDP/DD ratio were 3.76 and 2.25-8.15 in group A, 5.63 and 2.86-10.58 in group B, 10.23 and 0.91-47.71 in groups C, respectively. For the Fib/DD ratio, the 95% CIs was 0.02-2.21 in group A, 0.68-8.15 in group B, and 3.82-55.27 in groups C. Six abnormal results were identified after multiple dilutions, by comparison with other detection systems, and after HBR addition. CONCLUSIONS: The FDP/DD ratio is more reliable for identifying false results. If the FDP/DD ratio falls outside the 95% CI, it should be verified by different methods.

κ and λ urine free light chains: a new method for quantification.

BACKGROUND: Immunofixation electrophoresis of urinary proteins, coupled with densitometric analysis, is the gold standard method for determining urinary monoclonal free light chains (FLCs), i.e. Bence Jones protein. Recently, immunochemical methods have been developed for Bence Jones protein quantification, but no such method has been widely adopted. This study evaluated a new antibody-based immunoturbidimetry method for urinary FLC quantification, using immunofixation electrophoresis as reference. METHODS: κ and λ FLCs were measured in urine specimens from 95 (training cohort) and 103 (testing cohort) patients by both immunofixation electrophoresis and immunoturbidimetry. RESULTS: There was almost perfect concordance in the training cohort between the new immunoturbidimetry assay and immunofixation electrophoresis and substantial agreement, with Cohen kappa of 0.85 and 0.75, for κ and λ FLC determination, respectively. Results were confirmed in the testing cohort, where Cohen kappa was 0.86 for κ and 0.94 for λ FLCs. The κ FLC assay had 88% sensitivity and 98%-100% specificity; the λ FLC assay had 94% and 96% sensitivity and 91% and 99% specificity in the training and testing cohorts, respectively. CONCLUSIONS: The new immunochemical method has a satisfactory performance and almost perfect agreement with immunofixation electrophoresis and gives the advantage of FLC quantification.

Strong correlation and high comparability of capillary electrophoresis and three different methods for HbA1c measurement in a population without hemoglobinopathy.

The present study aimed to investigate the comparability of capillary electrophoresis (CE) and three different methods for HbA1c measurement. The 270 whole blood samples with normal hemoglobin profiles were analyzed for HbA1c values by the Roche turbidimetric inhibition immunoassay (TINIA), the Mindray enzymatic assay (EA), the Arkray high-performance liquid chromatography (HPLC) in comparison with the Sebia CE. The within-laboratory coefficient of variation of all four methods was within the accepted goal (<2%), showing good performance of all of these methods. Pairwise comparisons of HbA1c values obtained by CE and other methods were determined in both total group and subgroups (HbA1c levels of <6.5%, 6.5-8% and >8%). Mean differences of HbA1c values in all groups were very small in which the mean HbA1c value measured by EA was lower while those by TINIA and HPLC were higher than that of CE. The majority of different values were within the limits of agreement in Bland-Altman analysis, indicating good agreement between CE and the others. Less than 5% of percentage differences were out of the total allowable error limit in all groups, showing that differences of HbA1c values between CE and other methods were not clinically significant. Pairwise comparisons of HbA1c values of CE and the others in Passing-Bablok regression and Spearman rank correlation studies displayed high concordance and strong correlation in all groups. In conclusion, the present study showed strong correlation, high comparability and consistent results for HbA1c measurement between capillary electrophoresis and the other three different methods.

Validation of an equine serum amyloid A assay with an unusually broad working range.

BACKGROUND: Serum amyloid A (SAA) is a major equine acute phase protein and of great value in detection and monitoring of inflammation. A new immunoturbidometric assay based on monoclonal antibodies (VET-SAA, Eiken Chemical Co., Japan) may be useful for SAA measurements in routine diagnostic laboratories. The aim of the study was to validate the VET-SAA immunoturbidometric assay and use it to measure serum SAA concentrations in a variety of clinical cases. Precision was assessed by intra- and interassay coefficients of variation of repeated measurements of serum pools (low, intermediate, high concentrations of SAA). Accuracy was estimated by linearity under dilution. Detection limit was determined by replicate determinations of ionized water. Measurements were compared to measurements performed in a previously validated SAA assay (LZSAA assay, Eiken Chemical Co., Japan). Subsequently, the VET-SAA assay was used for measuring serum SAA concentrations in horses with and without inflammation. RESULTS: Detection limit was 1.2 mg/L. Without modifications, the assay measured SAA concentrations with acceptable reliability in a broad concentration range (0 to > 6000 mg/L). In the 0-3000 mg/L range, the assay demonstrated good precision and accuracy, and concentrations correlated well with those obtained in the LZSAA assay, albeit with a slight systematic bias. Concentrations of SAA assessed in horses with and without inflammation followed the expected pattern, with significantly higher concentrations in horses with systemic inflammation than in healthy horses and horses with non-inflammatory disease. CONCLUSIONS: The assay was unique in its ability to measure SAA concentrations with acceptable reliability over an extreme concentration range. This is relevant in the equine species, where SAA concentrations may reach very high concentrations.

Accuracy Evaluation of a Tetrabromophenolphthalein Ethyl Ester Colorimetric Assay for Urinary Albumin.

BACKGROUND: The tetrabromophenolphthalein ethyl ester (TBPE) assay has been used to quantify urinary albumin in point-of-care devices. We assessed the accuracy of this TBPE assay for urinary albumin through comparison with an established immunoturbidimetric method (ADVIA 1800 Chemistry System, Siemens). METHODS: We developed a TBPE assay protocol to quantify albumin in the range associated with microalbuminuria (0-200 mg/L). The Jaffe reaction and a 3-dimensional (3D) surface were used to compensate for creatinine interference. Spiked simulated urine samples and patient samples were used to compare the TBPE assay with the immunoturbidimetric method. Multiple linear regression was used to analyze factors that could account for discrepancies between the 2 methods. RESULTS: We found that creatinine interfered with the TBPE assay. To compensate, a 3D surface was successfully used to quantify albumin in spiked deionized water and simulated urine samples. In spiked simulated urine samples, the immunoturbidimetric method underestimated the albumin concentration by 2 to 45 mg/L, and the TBPE assay overestimated it by 9 to 82 mg/L. In patient samples, the albumin concentrations measured with the TBPE assay and the immunoturbidimetric method differed by an average of 184 mg/L. CONCLUSIONS: The TBPE assay is a function of the creatinine concentration, and a 3D surface can be used to provide accurate albumin concentrations for standard samples. The corrected TBPE method and the immunoturbidimetric method deviated from known concentrations of spiked samples. Further investigation and comparisons with a third albumin measurement method, such as LC-MS/MS, are necessary before conclusions on the accuracy of the TBPE assay can be made.

Kinetic Approach Extends the Analytical Measurement Range and Corrects Antigen Excess in Homogeneous Turbidimetric Immunoassays.

BACKGROUND: Homogeneous turbidimetric immunoassays are widely used in the clinical laboratory and offer short assay times, reduced reagent costs, and the potential for full automation. However, these assays have a limited analytical measurement range (AMR) above which antigen excess leads to falsely low estimates of the analyte concentration (i.e., the hook effect). Traditional methods for correction of antigen excess require sample dilution, compromising time and cost-efficiency. Therefore, novel methods that extend the AMR are needed. METHODS: A kinetic model of a generic homogeneous turbidimetric immunoassay was built and then parameterized using a genetic algorithm. Kinetic features that could be used to extend the AMR were identified and subsequently validated with clinical data from consecutive measurements of 2 homogeneous turbidimetric immunoassays: κ serum free light chain and rheumatoid factor. RESULTS: A novel kinetic parameter, the area under the curvature (AUCU), was derived that increases in proportion to the analyte concentration in a range beyond the AMR of conventional end point methods. When applied to clinical data, the AUCU method provided a log-linear calibration curve in the zone of antigen excess extending the AMR by >10-fold for 2 different immunoassays. CONCLUSIONS: The AUCU method detects and corrects antigen excess, extending the AMR in homogeneous turbidimetric immunoassays. The advantage of this method over conventional methods would be a reduction in the number of repeated samples, resulting in significant time and cost savings.

Recomendaciones para la estandarización de la medida de lípidos y lipoproteínas. Recomendación (2018) / Recommendations for the standardisation of lipids and lipoproteins measurements. Recommendation (2018)

Este documento describe recomendaciones para la estandarización de la medida de las magnitudes lipídicas, puesto que resultan críticas para la toma de decisiones clínicas. Deben emplearse métodos recomendados validados frente a un método de referencia o definitivo, y materiales de control que cumplan con la Directiva Europea sobre Diagnóstico in vitro; deben cumplir también los objetivos recomendados por el National Cholesterol Education Program (NCEP) y la Sociedad Española de Medicina del Laboratorio (SEQCML). La determinación de colesterol de HDL por métodos homogéneos en equipos automatizados se considera aceptable para la práctica rutinaria, y la fórmula de Friedewald utilizable para estimar la concentración de colesterol de LDL siempre que las concentraciones de triglicéridos sean iguales o inferiores a 200mg/dL (2,3mmol/L); en otro caso, se recomienda utilizar la concentración de colesterol-no-HDL. La cuantificación rutinaria de apolipoproteínas A1 y B, y lipoproteína (a), puede efectuarse por métodos de inmunonefelometría e inmunoturbidimetría, con calibradores trazables a materiales de referencia

Some recommendations are presented for standardising the measurement of lipids and lipoproteins, as they are critical for clinical decisions making. Recommended methods validated against a reference or definitive method should be employed, as well as the use of control materials that comply with European Directives on in vitro diagnostics. Additionally, the chosen methods must comply with the objectives set forth by the National Cholesterol Education Program (NCEP) and by the Spanish Society of Laboratory Medicine (SEQCML). Determination of HDL cholesterol using automatic homogenous methods is considered acceptable for normal clinical practice, and the Friedewald Formula is considered to be usable to estimate LDL cholesterol concentration when triglyceride concentrations are below 200mg/dL (2.3mmol/L). If this should not be the case, the use of non-HDL cholesterol is recommended. Routine quantification of apolipoproteins A1 and B, and lipoprotein (a) can be measured using immunonephelometric or immunoturbidimetric methods, with calibrators that are traceable to reference materials

Evaluation of a Novel Anti-H. pylori Antibody Detection Kit by Latex Turbidimetric Immunoassay.

BACKGROUND: While all modalities used for diagnosis of Helicobacter pylori (H. pylori) have demonstrated sufficient sensitivity and specificity, each test has advantages and limitations. The serum test for anti-H. pylori antibody with the latex method is noninvasive, easy, and inexpensive; it is thus a useful tool for mass-screening for H. pylori. In this study, we evaluated the utility of a newly developed latex kit, in comparison with other serum diagnostic kits based on enzyme-linked immunosorbent assay (ELISA). METHODS: In total, 187 subjects (77: H. pylori-positive, 75: H. pylori-negative, 35: previous infection with H. pylori) seen at Oita University Hospital during the period from January 1988 to September 2014 were enrolled in the study. All subjects were evaluated with 4 types of serum H. pylori antibody kits. One modality was based on the use of latex (Denka Kit, Denka Seiken Co., Ltd., Tokyo, Japan). Three kits were based on the use of ELISA. The E-Plate II Eiken (Eiken Chemical Co., Ltd., Tokyo, Japan) is henceforth referred to as Kit A. The Premier H. pylori kit (Meridian Bioscience, Inc., USA) is referred to as Kit B. The Platelia H. pylori IgG (Bio-Rad, Marnes-la-Coquette, France) is referred to as Kit C. RESULTS: Evaluation of 152 study participants, including some who were positive for H. pylori and some who were negative, sensitivity, specificity, and accuracy values were as follows: for the Denka kit, these values were, respec-tively, 92.2%, 93.3%, and 92.8%. For Kit A, these values were 88.3%, 100.0%, and 194.1%. For Kit B, these values were 98.7%, 76.0%, and 87.5%. For Kit C, these values were 98.7%, 80.0%, and 89.5%. The specificity of Kit A was > 90%. Sensitivity was > 90% for Kits B and C. For the Denka kit, both sensitivity and specificity were > 90%. Among the 35 subjects previously infected with H. pylori, the rate of positive diagnosis was 48.6% (17/35) with the Denka kit, 17.1% (6/35) with Kit A, 54.3% (19/35) with Kit B, and 54.3% (19/35) with Kit C. The rate of positive diagnosis was significantly higher with the Denka kit than with Kit A (p < 0.05). CONCLUSIONS: An assay based on use of the latex method, H. pylori-latex Seiken, demonstrated satisfactory sensitivity and specificity for detecting serum levels of H. pylori antibody. The performance of this kit was equivalent to that of ELISA kits currently used for the same purpose. This kit is therefore considered to be extremely suitable for diagnosis of H. pylori and mass-screening of patients at high risk for gastric cancer.

Immunoturbidimetric Assay for Determination of Peripheral Blood C Reactive Protein on the Pentra MS CRP Hematology Analyzer.

BACKGROUND: The Pentra MS CRP hematology analyzer (hereinafter the Pentra analyzer) can simultaneously provide 5-part leukocyte differential and C-reactive protein (CRP). The aim of the study was to investigate the performance of CRP determination by the Pentra analyzer. METHODS: The precision, limit of quantitation (LoQ), carryover, linearity, stability, and comparability of the Pentra analyzer were determined. The Passing-Bablok regression analysis and the Bland-Altman graphs illustrated the correlation for CRP concentration analyzed by the Pentra analyzer and BN-II analyzer. RESULTS: The within-run precision of CRP determination by the Pentra analyzer had a CV < 2.0% in peripheral blood, which met the requirements of the instructions (CV ≤ 10%). The Pentra analyzer had a total CV of 5.35% and 5.52% at a CRP concentration of 4.1 and 80 mg/L, respectively. The LoQ value for the Pentra analyzer was 0.96 mg/L. The carryover was 0.57% for peripheral blood and 0.86% for plasma by the analyzer. The stability of CRP results was good, when the anticoagulation samples were stored at room temperature or 4°C within 48 hours (deviation < 5%). The linearity range for whole blood samples was 0 - 188.13 mg/L (r² = 0.9992). There was high correlation of the CRP results analyzed with the Pentra analyzer and BN II analyzer. The Passing-Bablok regression analysis and the Bland-Altman graphs showed the bias plot display excellent agreement between the two assays (the mean value for the Pentra 2.19 mg/L and the BN-II 2.35 mg/L, n = 101). CONCLUSIONS: The results of CRP determination by the Pentra analyzer have the advantages of accuracy and reliability, and it is suitable for routine use in emergency laboratory and small to medium-size laboratories.