Dimension Xpand Research Articles

Comparion of creatinine, blood urea nitrogen (BUN) and glucose measure-ments between gem premier chemstat and dimension Xpand plus analyser

Comparion of creatinine, blood urea nitrogen (BUN) and glucose measure-ments between gem premier chemstat and dimension Xpand plus analyser

Prevalence of Pre Diabetes and Type 2 Diabetes Mellitus among cement industry workers.

Objectives:Occupational and environmental pollution have become an imperative jeopardy for developing devastating metabolic diseases. Limited animal model studies have examined the impact of exposure to cement dust on metabolic conditions. This study aimed to assess the prevalence of pre-diabetes and Type-2 diabetic mellitus (T2DM) among non-smoking cement mill workers.Methods:This epidemiological cross sectional study was conducted in the “Department of Physiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia” during the period Oct 2016 to June 2017. Initially 310 cement mill workers were interviewed; after the interview and clinical history taking, 186 non-smoking cement mill employees were finally recruited. The cement mill employees were exposed to cement dust-related pollution in a cement industry for eight hours a day for six days a week. The mean age was 36.56 ± 0.78 years, mean BMI was 25.70 ± 0.29 m/kg2, and mean period of employment in the cement industry was 82.77 ± 6.95 months. HbA1c was measured using the Dimension Xpand Plus Integrated Chemistry System (USA).Results:The cement mill employees were divided into three groups: non-diabetics group, with glycated hemoglobin (HbA1c) <5.7%; pre-diabetics group, with HbA1c 5.7-6.4%; and diabetics group, with HbA1c >6.4%. Among the cement mill personnel, 79 (42.47%) were non-diabetics, 28 (15.05%) were pre-diabetics, and 79 (42.47%) were diabetics. The prevalence of pre-diabetes and T2DM among cement mill employees was considerably associated with the period of employment in the cement industry (p=0.032).Conclusions:Exposure to cement dust was associated with an increased prevalence of pre- diabetes and T2DM among cement industry employees.

Prevalence of Pre Diabetes and Type 2 Diabetes Mellitus among cement industry workers

Objectives: Occupational and environmental pollution have become an imperative jeopardy for developing devastating metabolic diseases. Limited animal model studies have examined the impact of exposure to cement dust on metabolic conditions. This study aimed to assess the prevalence of pre-diabetes and Type-2 diabetic mellitus (T2DM) among non-smoking cement mill workers.&#x0D; Methods: This epidemiological cross sectional study was conducted in the “Department of Physiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia” during the period Oct 2016 to June 2017. Initially 310 cement mill workers were interviewed; after the interview and clinical history taking, 186 non-smoking cement mill employees were finally recruited. The cement mill employees were exposed to cement dust-related pollution in a cement industry for eight hours a day for six days a week. The mean age was 36.56 ± 0.78 years, mean BMI was 25.70 ± 0.29 m/kg2, and mean period of employment in the cement industry was 82.77 ± 6.95 months. HbA1c was measured using the Dimension Xpand Plus Integrated Chemistry System (USA).&#x0D; Results: The cement mill employees were divided into three groups: non-diabetics group, with glycated hemoglobin (HbA1c) &lt;5.7%; pre-diabetics group, with HbA1c 5.7-6.4%; and diabetics group, with HbA1c &gt;6.4%. Among the cement mill personnel, 79 (42.47%) were non-diabetics, 28 (15.05%) were pre-diabetics, and 79 (42.47%) were diabetics. The prevalence of pre-diabetes and T2DM among cement mill employees was considerably associated with the period of employment in the cement industry (p=0.032).&#x0D; Conclusions: Exposure to cement dust was associated with an increased prevalence of pre- diabetes and T2DM among cement industry employees.&#x0D; doi: https://doi.org/10.12669/pjms.36.1.1266&#x0D; How to cite this:Meo SA, Bin-Muneif YA, BenOmran NA, AlSadhan MA, Hashem RF, Alobaisi AS. Prevalence of Pre Diabetes and Type 2 Diabetes Mellitus among cement industry workers. Pak J Med Sci. 2020;36(1):---------. doi: https://doi.org/10.12669/pjms.36.1.1266&#x0D; This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

“COMPARISON OF A RAPID SEMI-QUANTITATIVE LATEX AGGLUTINATION SLIDE METHOD AGAINST QUANTITATIVE PARTICLE ENHANCED TURBIDIMETRIC IMMUNOASSAY FOR MEASUREMENT OF C- REACTIVE PROTEIN”

Serum C - reactive protein (CRP) is an acute phase marker in humans that is useful for the diagnosis and monitoring of inflammatory disease. CRP measurement also helps in differential diagnosis, in the management of neonatal septicaemia and meningitis where standard microbiological investigations are very much time-consuming. Reliable method (Automated particle enhanced turbidimetric immunoassay) are preferable for routine evaluation of human serum CRP levels. Using such expensive methods in health centres in rural areas is not possible. The aim of this to evaluate whether human CRP levels could be measured by rapid method (Latex agglutination slide method) and compared with reliable method (particle enhanced turbidimetric immunoassay).The study included 400 participants, who attended Shree Krishna Hospital, Karamsad, whose CRP levels were done by particle enhanced turbidimetric immunoassay method in Siemens Dimension Clinical Chemistry Analyzer, RxL and Xpand and compared by rapid method (Latex Agglutination slide method), that will be useful in health centres in rural areas where expensive instruments are not available. We used SPSS for data analysis and Endnote X7 for references management. In present study, out of 400 (217 male and 183 female) participants, we found 337 participants had positive CRP levels (≥0.3 mg/dl) and 63 participants had negative CRP levels (&lt;0.3 mg/dl) by particle enhanced turbidimetric immunoassay method, whereas 303 had positive CRP levels (≥0.6mg/dl) and 97 had negative CRP levels (&lt;0.6mg/dl) by Latex Agglutination slide method. The correlation was positive between two methods with (r = 0.764, P -value &lt;0.0001). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 89.9%, 100%, 100%, and 64.94%, respectively, for the Latex Agglutination slide method, and 100%, 64.9%, 89.91% and 100%, respectively, for the particle enhanced turbidimetric immunoassay method. Serum C- reactive protein (CRP) levels can be reliably measured using the particle enhanced turbidimetric immunoassay method, but it is expensive, so we can use Latex agglutination slide method in rural areas for primary diagnosis only.&#x0D; Key Words: CRP, Latex Agglutination slide method, particle enhanced turbidimetric immunoassay method.

Comparison of PETINIA and LC-MS/MS for determining plasma mycophenolic acid concentrations in Japanese lung transplant recipients

BackgroundMycophenolic acid (MPA) treatment requires therapeutic drug monitoring to improve the outcome after organ transplantation. The aim of this study was to compare two methods, a particle enhanced turbidimetric inhibition immunoassay (PETINIA) and a reference liquid chromatography tandem mass spectrometry (LC-MS/MS) for determining plasma MPA concentrations from Japanese lung transplant recipients.MethodsPlasma MPA concentrations were determined from 20 Japanese lung transplant recipients using LC-MS/MS and the PETINIA on the Dimension Xpand Plus-HM analyzer.ResultsThe mean MPA concentration measured by PETINIA was significantly higher than that measured by LC-MS/MS (3.26 ± 2.73 μg/mL versus 2.82 ± 2.71 μg/mL, P < 0.0001). The result of the Passing Bablok analysis was a slope of 1.104 (95% confidence interval [CI], 1.036–1.150) and an intercept of 0.229 (95%CI, 0.144–0.315). Bland–Altman analysis revealed PETINIA overestimates plasma MPA concentration by 26.25% and 95%CI from 21.43 to 31.07%.ConclusionThe measurement of MPA by the PETINIA in Japanese lung transplant patients should evaluate the result with attention to positive bias.

Bias due to Preanalytical Dilution of Rodent Serum for Biochemical Analysis on the Siemens Dimension Xpand Plus.

Clinical pathology testing of rodents is often challenging due to insufficient sample volume. One solution in clinical veterinary and exploratory research environments is dilution of samples prior to analysis. However, published information on the impact of preanalytical sample dilution on rodent biochemical data is incomplete. The objective of this study was to evaluate the effects of preanalytical sample dilution on biochemical analysis of mouse and rat serum samples utilizing the Siemens Dimension Xpand Plus. Rats were obtained from end of study research projects. Mice were obtained from sentinel testing programs. For both, whole blood was collected via terminal cardiocentesis into empty tubes and serum was harvested. Biochemical parameters were measured on fresh and thawed frozen samples run straight and at dilution factors 2–10. Dilutions were performed manually, utilizing either ultrapure water or enzyme diluent per manufacturer recommendations. All diluted samples were generated directly from the undiluted sample. Preanalytical dilution caused clinically unacceptable bias in most analytes at dilution factors four and above. Dilution-induced bias in total calcium, creatinine, total bilirubin, and uric acid was considered unacceptable with any degree of dilution, based on the more conservative of two definitions of acceptability. Dilution often caused electrolyte values to fall below assay range precluding evaluation of bias. Dilution-induced bias occurred in most biochemical parameters to varying degrees and may render dilution unacceptable in the exploratory research and clinical veterinary environments. Additionally, differences between results obtained at different dilution factors may confound statistical comparisons in research settings. Comparison of data obtained at a single dilution factor is highly recommended.

Positivity threshold value for cardiac troponin lc in the diagnosis of perioperative myocardial infarction after on-pump cardiac surgery in adult patients

IntroductionL'objectif de cette étude prospective, réalisée sur une année au laboratoire de biochimie de l'HMIMV de Rabat, vise à étudier la cinétique de la Troponine Ic (TnIc) après chirurgie cardiaque sous circulation extracorporelle (CEC) en vue d'établir des valeurs seuils pour le diagnostic d'infarctus de myocarde péri-opératoire (IDMPO).MéthodesNous avons inclus 58 patients opérés pour chirurgie valvulaire ou pontage coronarien sous CEC. Ces patients ont été séparés en 3 groupes selon l'évolution clinique, biologique (TnIc) et électrique durant la période post opératoire précoce. Nous avons dosé et suivi la cinétique de la TnIc par une technique immuno-enzymatique, au moyen du réactif FlexR CTNI avant et après la CEC, à H0, H3, H6, H12, H21, H24 et H72 sur l'automate Dimension Xpand plusR de la société Siemens.RésultatsLes résultats obtenus sont plus élevés qu'en cardiologie, même chez le groupe des patients sans complications cardiaques post opératoires, avec un taux moyen de TnIc environ 2,5 fois supérieur à la valeur seuil en cardiologie. La cinétique de libération est significativement différente entre les 3 groupes (p‹0,05).ConclusionLa valeur seuil que nous proposons pour confirmer le diagnostic de l'IDMPO est de 13ng/ml obtenue entre H12 et H24. Nous recommandons, de ce fait, un à deux prélèvements vers H12 puis entre H20 et H24.

Therapeutic Drug Monitoring of Everolimus: Comparability of Concentrations Determined by 2 Immunoassays and a Liquid Chromatography Tandem Mass Spectrometry Method.

Therapeutic drug monitoring is recommended to guide therapy with the immunosuppressant everolimus (EVL) in solid organ transplantation to prevent rejections and to limit toxicity. For therapeutic drug monitoring, predose EVL concentrations are measured in whole blood mainly by liquid chromatography tandem mass spectrometry (LC-MS/MS). In addition, 2 immunoassays [Quantitative Microsphere System (QMS) EVL and Elecsys EVL] are commercially available. The aim of this study was to evaluate the comparability of EVL results determined with the 2 immunoassays and a validated LC-MS/MS test using samples from kidney, liver, and heart transplant (KT, LT, and HT, respectively) recipients. Analysis of predose samples from KT (n = 56), LT (n = 60), and HT (n = 59) recipients, obtained at variable time points after transplantation, was performed by LC-MS/MS and with the 2 immunoassays. The QMS EVL assay was applied on Dimension Xpand Plus and the Elecsys EVL assay on cobas e 411 analyzer. Results were compared by the Spearman's rank correlation coefficient, unbiased Passing and Bablok linear regression test, and Bland-Altman plot. Results generated with both immunoassays correlated well with those of LC-MS/MS. An overestimation of EVL concentrations by the Elecsys EVL compared with LC-MS/MS was observed (mean bias: 34.2%). Using the QMS EVL, a small but significant negative deviation (mean bias: -8.0%) was found. Looking at KT, HT, and LT samples separately, the bias to LC-MS/MS seen with the Elecsys EVL was similar. With the QMS EVL, the best agreement was observed with the KT samples followed by LT and HT. Results generated by the 3 methods are not consistent regarding their diagnostic value. Both laboratories and manufacturers should take care to inform their costumers about the between-method differences to avoid misinterpretation of the results in clinical practice.

Biomarker NTproBNP in Patients with Severe CommunityAcquired Pneumonia

The aim of the study was to determine the correlation between blood levels of Nterminal portion of the inactive precursor of natriuretic peptide of Btype (NTproBNP) and hemodynamic, clinical and laboratory parameters in the course of intensive treatment of patients with severe communityacquired pneumonia (CAP). Materials and methods. The study included 12 patients (10 men and 2 women) with severe CAP, age 25—88 (51.5 (41.25; 69)) years. The severity of the condition was as follows (averages and percentiles): on a scale of CURB65 — 3—5 (4; 4,5) scores, APACHE II — 16—33 (23 (18.75; 25)) scores, SOFA — 6—16 (10 (9; 12.75)) points. Concentartions of NTproBNP in venous blood 24—36 h post admission and on day 5 of treatment were determined by analyzer Dimension Xpand Plus (Siemens). Results. Within 24—36 hours after the admission concentration of NTproBNP was 783.5 (460.75; 4150.25) pg/ml. The content of the biomarker remained higher than in norm in 66.7% of patients. By the 5th day the concentration of the biomarker was 537 (376.25, 1334) pg/ml. In surviving patients (66.7%), the concentration of NT proBNP was decreasing (P=0.008) to day 5 of treatment from 918 (560, 8501) to 391 (341, 1010) pg/ml. CAP patients who did not survived later (32.3%) exhibited no decrease of the biomarker concentration. Significant correlation between NTproBNP on admission to ISU and index of total peripheral vascular resistance on day 2 of intensive treatment (r=0.63; p<0.05) and day 5 (r=0.58, P<0.05) was revealed. Echocardiography systolic pulmonary artery pressure correlated with the content of NTproBNP 24—36 hours after admission to the Intensive Care Unit and on the 5th day of treatment. Conclusion. We suggested that the reason for increased concentration of NTproBNP is an overload of the right ventricle myocardium due to pulmonary hypertension as a characteristic of acute respiratory distress syndrome.

Association of Exposure to Radio-Frequency Electromagnetic Field Radiation (RF-EMFR) Generated by Mobile Phone Base Stations with Glycated Hemoglobin (HbA1c) and Risk of Type 2 Diabetes Mellitus.

Installation of mobile phone base stations in residential areas has initiated public debate about possible adverse effects on human health. This study aimed to determine the association of exposure to radio frequency electromagnetic field radiation (RF-EMFR) generated by mobile phone base stations with glycated hemoglobin (HbA1c) and occurrence of type 2 diabetes mellitus. For this study, two different elementary schools (school-1 and school-2) were selected. We recruited 159 students in total; 96 male students from school-1, with age range 12–16 years, and 63 male students with age range 12–17 years from school-2. Mobile phone base stations with towers existed about 200 m away from the school buildings. RF-EMFR was measured inside both schools. In school-1, RF-EMFR was 9.601 nW/cm2 at frequency of 925 MHz, and students had been exposed to RF-EMFR for a duration of 6 h daily, five days in a week. In school-2, RF-EMFR was 1.909 nW/cm2 at frequency of 925 MHz and students had been exposed for 6 h daily, five days in a week. 5–6 mL blood was collected from all the students and HbA1c was measured by using a Dimension Xpand Plus Integrated Chemistry System, Siemens. The mean HbA1c for the students who were exposed to high RF-EMFR was significantly higher (5.44 ± 0.22) than the mean HbA1c for the students who were exposed to low RF-EMFR (5.32 ± 0.34) (p = 0.007). Moreover, students who were exposed to high RF-EMFR generated by MPBS had a significantly higher risk of type 2 diabetes mellitus (p = 0.016) relative to their counterparts who were exposed to low RF-EMFR. It is concluded that exposure to high RF-EMFR generated by MPBS is associated with elevated levels of HbA1c and risk of type 2 diabetes mellitus.

Comparison of Hemoglobin A1c assay performance on two different commercial systems

Introduction: Glycated hemoglobin (HbA1c) is formed by non-enzymatic binding of glucose to the free amino group of the N-terminal end of the ß-chain of hemoglobin A. HbA1c is representative of the mean blood glucose level over three months. The aim of the study was to evaluate the Hemoglobin A1c immunoturbidimetric assay performance on two different commercial systems.Methods: We evaluated the precision and trueness for determination of HbA1c in whole blood. Concentrations of total hemoglobin and HbA1c were evaluated on Dimension Xpand (Siemens) and Cobas 501 (Roche) analyzers. HbA1c was measured in a latex agglutination inhibition test. Commercial controls Liquichek Diabetes Control Level 1 and Liquichek Diabetes Control Level 2 (Bio Rad) at two levels were used for quality control. Analytical validation of HbA1c included: within-run imprecision, between-day imprecision, inaccuracy and comparison determination on the human samples on 2 systems: Dimension Xpand and Cobas 501 analyzers. Results: Within-run imprecision on the commercially controls for Level 1 is 4.5% and Level 2 is 3.2% between-day imprecision on commercially controls is 6.1% Level 1 and 5.1% Level 2 for respectively inac- curacy on commercially controls for Level 1 is 1.8% and Level 2 is 4.8%. Method comparison on human samples shows the correlation coefficient of 0.99.Conclusion: The presented results of the analytical evaluation methods for the determination of HbA1c showed an acceptable accuracy and precision.

The External Quality Assessment Scheme (EQAS): Experiences of a medium sized accredited laboratory

IntroductionWe put forth our experiences of EQAS, analyzed the result discrepancies, reviewed the corrective actions and also put forth strategies for risk identification and prevention of potential errors in a medical laboratory. MethodsFor hematology, EQAS samples – blood, peripheral and reticulocyte smears – were received quarterly every year. All the blood samples were processed on HMX hematology analyzer by Beckman-Coulter. For clinical chemistry, lyophilized samples were received and were processed on Siemens Dimension Xpand and RXL analyzers. For microbiology, EQAS samples were received quarterly every year as lyophilized strains along with smears and serological samples. ResultsIn hematology no outliers were noted for reticulocyte and peripheral smear examination. Only one outlier was noted for CBC. In clinical chemistry outliers (SDI≥2) were noted in 7 samples (23 parameters) out of total 36 samples (756 parameters) processed. Thirteen of these parameters were analyzed as random errors, 3 as transcriptional errors and seven instances of systemic error were noted. In microbiology, one discrepancy was noted in isolate identification and in the grading of smears for AFB by Ziehl Neelsen stain. ConclusionEQAS along with IQC is a very important tool for maintaining optimal quality of services.

Comparability and Imprecision of 8 Frequently Used Commercially Available Immunoassays for Therapeutic Drug Monitoring

The development of new immunoassays for therapeutic drug monitoring and the adaptation of current assays on new analytical platforms has led to a plethora of different tests. This variability may influence comparability between the methods and affect interpretation of test results used for guiding drug treatment. Comparability and imprecision of 8 immunoassays for therapeutic drug monitoring were evaluated using 6 different analyzers from 3 manufacturers. Current and previous generation analytical systems used were Architect and AxSym (Abbott Laboratories), cobas c 501 module and COBAS INTEGRA 800 analyzer (Roche Diagnostics GmbH), and Dimension Vista and Dimension Xpand (Siemens Healthcare Diagnostics Inc). Carbamazepine, digoxin, phenobarbital, phenytoin, theophylline, tobramycin, vancomycin, and valproic acid were measured using leftover routine samples. Good performance and comparability of the drug assays was seen on all systems for carbamazepine, phenytoin, and valproic acid except for phenytoin on the Dimension Vista. Deviations from the acceptance criteria were found with digoxin, phenobarbital, theophylline, tobramycin, and vancomycin. Despite a change of the analytical principle on the Roche systems for most drugs, the results demonstrated a very good between-system comparability of the concentration measured. Systematic deviations were found between AxSYM and ARCHITECT for digoxin, phenobarbital, and tobramycin, and between Dimension Xpand and Dimension Vista for digoxin and vancomycin. The study revealed differences between assays, platforms, and assay principles. Care should be taken if methods or instruments are replaced in a laboratory. Laboratories are advised to perform their own method comparison studies and to inform their customers about the effect on the therapeutic ranges in case of observed clinically significant deviations.

Multiple immunoassay systems are negatively interfered by circulating cardiac troponin I autoantibodies

Circulating cardiac troponin I (cTnI) autoantibodies have recently been detected in more and more patients with myocardial injury. In the present study, a total of 121 patients with acute myocardial infarction (AMI) were screened for cTnI autoantibodies using an indirect ELISA. Positive results were further confirmed by Western blot analysis. As a result, 13 autoantibody-positive sera were identified, in which cTnI values detected by different immunoassay systems are very different. Further evaluation revealed low recovery in one of the 13 samples with the Access 2 system (Beckman Coulter, 2^ generation), one low and one moderate recovery sample with Architect i2000 (Abbott), one low and two moderate with AxSYM (Abbott), two low and three moderate with Dimension Xpand (Dade Behring, 2^ generation), and four low and one moderate with Vidas (bioMérieux). Our work demonstrates that circulating cTnI autoantibodies occur in part of patients with AMI and, for the first time to our knowledge, shows that these autoantibodies can result in considerable negative interference in all the five commonly used cTnI immunoassay systems, which may lead to incorrect diagnoses and following treatments. The indirect ELISA established in our laboratory is suitable for a rapid preliminary screening for cTnI autoantibody in clinical work.

Multisite Analytical Evaluation of the Abbott ARCHITECT Cyclosporine Assay

The objective of this study was to evaluate the analytical performance of the Abbott ARCHITECT Cyclosporine (CsA) immunoassay in 7 clinical laboratories in comparison to liquid chromatography/tandem mass spectrometry (LC/MS/MS), Abbott TDx, Cobas Integra 800, and the Dade Dimension Xpand immunoassay. The ARCHITECT assay uses a whole blood specimen, a pretreatment step with organic reagents to precipitate proteins and extract the drug, followed by a 2-step automated immunoassay with magnetic microparticles coated with anti-CsA antibody and an acridinium-CsA tracer. Imprecision testing at the 7 evaluation sites gave a range of total % coefficient of variations of 7.5%-12.2% at 87.5 ng/mL, 6.6%-14.3% at 411 ng/mL, and 5.2%-10.7% at 916 ng/mL. The lower limit of quantification ranged from 12 to 20 ng/mL. Purified CsA metabolites AM1, AM1c, AM4N, AM9, and AM19 were tested in whole blood by the ARCHITECT assay and showed minimal cross-reactivity at all 7 sites. In particular, AM1 and AM9 cross-reactivity in the ARCHITECT assay, ranged from -2.5% to 0.2% and -0.8% to 2.2%, respectively, and was significantly lower than for the TDx assay, in which the values were 3.2% and 16.1%, respectively. Comparable testing of metabolites in the Dade Dimension Xpand assay at 2 evaluation sites showed cross-reactivity to AM4N (6.4% and 6.8%) and AM9 (2.6% and 3.6%) and testing on the Roche Integra 800 showed cross-reactivity to AM1c (2.4%), AM9 (10.7%), and AM19 (2.8%). Cyclosporine International Proficiency Testing Scheme samples, consisting of both pooled specimens from patients receiving CsA therapy as well as whole-blood specimens supplemented with CsA, were tested by the ARCHITECT assay at 6 sites and showed an average bias of -24 to -58 ng/mL versus LC/MSMS CsA and -2 to -37 ng/mL versus AxSYM CsA. Studies were performed with the ARCHITECT CsA assay on patient specimens with the following results: ARCHITECT CsA assay versus LC/MSMS, average bias of 31 ng/mL; ARCHITECT versus the Dade Dimension assay (4 sites), average biases of -7 to -228 ng/mL; ARCHITECT versus AxSYM and TDx, average biases of -4 and -53 ng/mL, respectively. Spearman correlation coefficients were >or=0.89. The ARCHITECT CsA assay has significantly reduced CsA metabolite interference relative to other immunoassays and is a convenient and sensitive semiautomated method to measure CsA in whole blood.

Therapeutic monitoring of Tacrolimus: Aberrant results by an immunoassay with automated pretreatment

Background and aims The therapeutic monitoring of Tacrolimus (FK506) is necessary since low doses may cause graft rejection while overdosage is linked to nephrotoxicity, neurotoxicity, and many other adverse effects. Occasional notices of elevated values recorded in patients under maintenance regimen have prompted us to record all results exceeding the therapeutic range (>15 ng/mL) with no clinical signs or explanation and to compare the routine method (Siemens-Dade Dimension XPand) with other assays. Methods Eighty-four whole blood samples from 8 patients have been assayed by Dimension and by one or more of three other commercial assays (CMIA and MEIA, Abbott; EMIT, Siemens-Dade). As a reference, an automated LC-MS/MS method has been performed. Results In all cases the raised Tacrolimus values were observed only by ACMIA, while the correlation ( r 2) of the other assays with LC-MS/MS was excellent for CMIA (0.97) and good for MEIA (0.88) and EMIT (0.83). The aberrant results were often recorded over a span of several weeks or months and could not be ascribed to a common cause. Discussion Abnormally high Tacrolimus results by the ACMIA method have been observed in 1% of the patients currently followed up in our Center. Since these results may lead to erroneous adjustments of the drug dosage, we suggest checking any elevated or clinically unexplained Tacrolimus result by the ACMIA assay with other method(s) requiring an external pretreatment.

Evaluation of 2 Immunoassays for Monitoring Low Blood Levels of Tacrolimus

The objective of this study was to evaluate the analytical performance of 2 new tacrolimus immunoassays (Dade Dimension Xpand and Abbott ARCHITECT) for therapeutic drug monitoring as possible replacements for the current method in our laboratory, the Abbott IMx tacrolimus assay. Attending physicians at our institute desire to minimize calcineurin inhibitor therapy in kidney allograft recipients to prolong graft survival and improve the quality of life of their patients. Proposed future target trough levels of tacrolimus in whole blood are in the range of 2-4 ng/mL, which requires an assay with a limit of quantification (LOQ) below this range, ideally around 1 ng/mL (European Consensus Recommendation from the Committee on Tacrolimus Optimization). Method comparison analysis of the Dade and ARCHITECT assays showed good correlation to the IMx assay, with correlation coefficients of 0.94 and 0.96, respectively. Both assays reported tacrolimus concentrations lower on average than IMx as demonstrated by slopes of 0.83 (Dade) and 0.93 (ARCHITECT). LOQ for both Dade instruments tested was >4 ng/mL, whereas the LOQ for the ARCHITECT i2000 and i1000 instruments was 0.8 and 0.5 ng/mL, respectively (upper 95% confidence limit). Values reported from both Dade instruments were observed to shift over time, whereas the values on the IMx and ARCHITECT instruments were stable. The Abbott ARCHITECT Tacrolimus assay is a sensitive and precise assay that meets the new LOQ recommendation, 1 ng/mL, for monitoring tacrolimus in whole blood.

Evaluation of the VITROS 5,1 FS analyzer in a large clinical laboratory: comparison of methods using different specimens and chemistry systems / Evaluation des Systems VITROS 5,1 FS in einem großen klinischen Laboratorium: Methodenvergleiche mit verschiedenen Probenmaterialien und Systemen

Abstract The clinical chemical analysis system Vitros 5,1 FS (Ortho Clinical Diagnostics, Neckargemünd, Germany) combines on one platform multilayer film technology with a newly developed technology based on conventional wet chemistry. We report the first extensive evaluation of this novel analyzer, establishing precision data, accuracy, and linearity of MicroSlide technology analytes and analytes using the newly developed MicroTip technology. For comparison, measurements with the analysis systems Beckman-Coulter DXC800 and Immage or Siemens Healthcare Diagnostics Dimension Xpand, and plasma, serum, urine and cerebrospinal fluid (CSF) samples as well as blood from routine operations were employed, respectively. For within-run imprecision, coefficients of variation between 0.2% and 5.5% were calculated. Coefficients of variation for quality control materials from day-to-day ranged from 0.6% to 7.1%. In all examined analytes, except hemoglobin A1c, calculated inaccuracies were within the acceptable ranges of the national directives for quality assurance (RiliBÄK, directives issued by the German Medical Association). Method comparison demonstrated good agreement between MicroSlide assays and wet chemistry methods with correlation coefficients ranging from 0.872 to 0.998. For the MicroTip assays, the calculated correlation coefficients ranged from 0.968 to 0.994. In conclusion, the Vitros 5,1 FS analyzer is a reliable analysis system which can be easily integrated into clinical chemical routine and which can also be applied for analysis of CSF, urine, and blood samples.

Analytical evaluation of the Abbott ARCHITECT cyclosporine assay in comparison to LC/MS/MS and Dade Dimension Xpand

Analytical evaluation of the Abbott ARCHITECT cyclosporine assay in comparison to LC/MS/MS and Dade Dimension Xpand

Adaptation of methotrexate determination in plasma with Dimension Xpand

The treatment with methotrexate at high doses is responsible of many side effects. It's necessary to evaluate serum methotrexate rate to monitor the administration of the methotrexate antagonist, the folinic acid. The aim of this study is to validate the determination of methotrexate in plasma using the automate Xpand Dimension (Dade Behring). Assay results were linearly related to the concentration for the wide range which was examinated (0.15 - 1.4 micromol/L). We report the precision, accuracy, linearity, sensitivity of this assay. The CV was less than 10%. We present the results of correlations with Aca (Dade Behring) and Cobas Mira (Roche). The reagent cartridge in the instrument and the calibration are stable during 28 days.