Search

Background Using middleware solutions, it is possible to implement concentration-dependent analyte-specific hemolysis rejection limits. This makes day-to-day reporting of clinical specimens more efficient and potentially lowers sample rejection rates compared to a “one-size-fits-all” approach (i.e., solely based on a single cutoff provided in the package insert). Methods Hemolysis interference studies were performed at multiple analyte concentrations for three frequently ordered tests. For each assay, concentration-dependent hemolysis rejection limits were designed based on the total allowable error (TAE) for the analyte as well as the clinical significance of such incurred inaccuracy at the respective concentrations. In general, the following rationale was used: if the interference exceeds 10% (or package insert cutoffs), a comment is placed on the result. If the interference exceeds the TAE, the result will not be reported. Reduction in specimen rejection rates were estimated by comparing the incurred specimen rejection rates when package inserts’ vs concentration-dependent hemolysis interference limits were applied to a data set in our institute during a three-month period. Results Concentration-dependent analyte-specific hemolysis rejection thresholds were designed for three commonly ordered assays that are especially susceptible to hemolysis interference. It is estimated that these novel thresholds for aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and direct bilirubin (DBIL) reduced specimen rejection rates from 9.3% to 1.3%, 31.4% to 4.8%, and 19.9% to 7.1%, respectively. Conclusions Concentration-dependent analyte-specific hemolysis rejection thresholds for three commonly ordered assays can reduce rejection rates without significantly compromising the quality of test results.

Background Preeclampsia is a leading cause of maternal and neonatal mortality and morbidity worldwide. Diagnosis of the condition is currently limited to utilization of nonspecific signs and symptoms. However, identification of potential pathogenic biomarkers may support earlier diagnosis and ultimately improved prognosis. Content The current models of preeclampsia suggest that the disease has components of abnormal placentation, a degree of angiogenic imbalance and endothelial dysfunction. Angiogenic factors such as soluble fms-like tyrosine kinase-1 and soluble endoglin increase while placental growth factor concentrations decrease in the circulation weeks before the onset of the disease. Multiple studies have looked at the capacity of angiogenic factors for the prediction of preeclampsia and adverse pregnancy outcomes. Summary The goal of this review is to focus on the role of angiogenic factors in the pathogenesis of preeclampsia and use of angiogenic biomarkers for risk stratification, diagnosis, and prognosis of the disease.

Background Several opioids have pharmacogenomic associations impacting analgesic efficacy. However, germline pharmacogenomic testing is not routinely incorporated into supportive oncology. We hypothesized that CYP2D6 profiling would correlate with opioid prescribing and hospitalizations. Materials and Methods We analyzed 61,572 adult oncology patients from 2012 to 2018 for opioid exposures. CYP2D6 metabolizer phenotype (ultra-rapid [UM], normal metabolizer [NM], intermediate [IM], or poor [PM]), the latter two of which may cause inefficacy of codeine, tramadol, and standard-dose hydrocodone, was determined for patients genotyped for reasons unrelated to pain. The primary endpoint was number of opioid medications received during longitudinal care (IM/PMs vs. NMs). Secondary endpoint was likelihood of pain-related hospital encounters. Results Most patients with cancer (n = 34,675, 56%) received multiple opioids (average 2.8 ± 1.6/patient). Hydrocodone was most commonly prescribed (62%), followed by tramadol, oxycodone, and codeine. In the CYP2D6 genotyped cohort (n = 105), IM/PMs received a similar number of opioids (3.4 ± 1.4) as NMs (3.3 ± 1.9). However, IM/PMs were significantly more likely to experience pain-related hospital encounters compared with NMs, independent of other variables (odds ratio [OR] = 5.4; 95% confidence interval [CI], 1.2–23.6; p = .03). IM/PMs were also more likely to be treated with later-line opioids that do not require CYP2D6 metabolism, such as morphine and hydromorphone (OR = 3.3; 95% CI, 1.1–9.8; p = .03). Conclusion CYP2D6 genotype may identify patients with cancer at increased risk for inadequate analgesia when treated with typical first-line opioids like codeine, tramadol, or standard-dose hydrocodone. Palliative care considerations are an integral part of optimal oncology care, and these findings justify prospective evaluation of preemptive genotyping as a strategy to improve oncology pain management. Implications for Practice Genomic variation in metabolic enzymes can predispose individuals to inefficacy when receiving opioid pain medications. Patients with intermediate and/or poor CYP2D6 metabolizer status do not adequately convert codeine, tramadol, and hydrocodone into active compounds, with resulting increased risk of inadequate analgesia. This study showed that patients with cancer frequently receive CYP2D6-dependent opioids. However, patients with CYP2D6 intermediate and poor metabolizer status had increased numbers of pain-related hospitalizations and more frequently required the potent non-CYP2D6 opioids morphine and hydromorphone. This may reflect inadequate initial analgesia with the common “first-line” CYP2D6-metabolized opioids. Preemptive genotyping to guide opioid prescribing during cancer care may improve pain-related patient outcomes.

ObjectivesTo evaluate the analytical and clinical performance of the Truvian Easy Check coronavirus disease 2019 (COVID-19) IgM/IgG anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody test.Serologic assays have become increasingly available for surveillance through the Food and Drug Administration emergency use authorization in the ongoing COVID-19 global pandemic. However, widespread application of serologic assays has been curbed by reports of faulty or inaccurate tests. Therefore, rapid COVID-19 antibody tests need to be thoroughly validated prior to their implementation.MethodsThe Easy Check device was analytically evaluated and its performance was compared with the Roche Elecsys anti-SARS-CoV-2 antibody assay. The test was further characterized for cross-reactivity using sera obtained from patients infected by other viruses. Clinical performance was analyzed with polymerase chain reaction-confirmed samples and a 2015 prepandemic reference sample set.ResultsThe Easy Check device showed excellent analytical performance and compares well with the Roche Elecsys antibody assay, with an overall concordance of 98.6%. Clinical performance showed a sensitivity of 96.6%, a specificity of 98.2%, and an overall accuracy of 98.1%.ConclusionsThe Easy Check device is a simple, reliable, and rapid test for detection of SARS-CoV-2 seropositivity, and its performance compares favorably against the automated Roche Elecsys antibody assay.

Background The interest for vitamin D has exponentially increased testing demand for 25-hydroxy vitamin D [25(OH)D]. Consequently, many laboratories are switching from LC-MS/MS methods to automated, high-throughput immunoassays. One of the major potential issues with these assays has been the lack of cross-reactivity with 25(OH)D2. Methods We have evaluated the Roche Elecsys vitamin D total II assay for accuracy by comparing 79 patient samples with LC-MS/MS. The cross-reactivity for 25(OH)D2 was evaluated by analyzing samples with high 25(OH)D2 separately and estimating 25(OH)D2 recovery, as well as by spiking of 25(OH)D2. The assay was further evaluated for precision, linearity, sample type, and common interferences. Results There was mostly good agreement between the Elecsys and LC-MS/MS assays (Deming regression: y = 0.95x + 0.70), with an overall bias of 2.3% (−0.84 ng/mL). However, there were 6 out of 79 (7.6%) discordant samples. The Deming regression for samples with high 25(OH)D2 compared to LC-MS/MS showed similar slope and intercept (y = 0.97x − 1.1). The average recovery of 25(OH)D2 for these samples was 90%. The initial precision studies were in general agreement with the package insert, but long-term clinical use showed higher-than-claimed imprecision (11.7%–14.4% at 12 ng/mL and 6.9%–7.6% at 27 ng/mL; claimed: 7.2% and 5.0%, respectively). We observed 1 falsely high result in plasma, an issue previously addressed by Roche in a medical device correction. Conclusions The analytical performance of the Roche Vitamin D assay was acceptable, and the assay had a good cross-reactivity for 25(OH)D2.

Objectives To evaluate the analytical and clinical performance of the automated Elecsys anti–severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody (Elecsys Ab) assay on the Roche cobas e602 analyzer. With the ongoing global coronavirus disease 2019 (COVID-19) pandemic, widespread and routine serologic testing of SARS-CoV-2 remains a pressing need. To better understand its epidemiologic spread and to support policies aimed at curtailing further infections, reliable serologic testing is crucial for providing insight into the dynamics of the spread of COVID-19 on a population level. Methods The presence of anti–SARS-CoV-2 antibodies in polymerase chain reaction–positive, confirmed COVID-19 patient samples was determined using the Elecsys Ab assay on the Roche cobas e602 analyzer. The precision and cross-reactivity of the Elecsys Ab assay were characterized and its performance was compared against the EuroImmun IgA/IgG antibody (EuroImmun Ab) assay. Calculated sensitivity, specificity, and positive and negative predictive values were assessed. Results The Elecsys Ab assay demonstrated good precision, had no cross-reactivity with other viral samples, and showed 100% concordance with the EuroImmun Ab assay. Excellent clinical performance with respect to sensitivity, specificity, and positive and negative predictive values was observed. Conclusions The Elecsys Ab assay is a precise and highly reliable automated platform for clinical detection of seropositivity in SARS-CoV-2 infection.

Background CYP2D6 is involved in the oxidative metabolism of approximately 20% of all clinically used medications. Genotyping cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6), is a challenge because of the high complexity of the locus. Methods Twenty-nine CYP2D6 sequence variants were genotyped in 50 deidentified patient samples and 29 Coriell DNAs by Invader assay, and results were compared with Infiniti assay and Sanger sequencing. To determine CYP2D6 copy number, 3 TaqMan real-time hydrolysis probes were used and results were compared with long-range PCR. Discrimination of the duplicated alleles was done on 17 DNA samples with 3 copies of CYP2D6 by long-range PCR followed by Invader genotyping and single nucleotide extension for the comparison. Results Complete concordance was observed for all samples between platforms except for 2 samples due to the lack of the *45 allele in the Infiniti panel. Reproducibility with the Invader assay and TaqMan copy number was 100%. Analytical sensitivity using DNA with 2 copies was determined to be 10 ng DNA for the Invader assay and 1 ng/μL DNA for the TaqMan assay, respectively. Complete concordance and reproducibility were observed for duplicated allele discrimination with the exception of 1 sample, determined to be *29/*43X2 by the Invader test and *1X2/*29 by the Infiniti method, which did not test for *43. Conclusions This validation study showed that Invader and TaqMan assay combined panel provides an attractive, valid, highly accurate, and reproducible approach for CYP2D6 genotyping for clinical implementation.

Background Preeclampsia is a leading hypertensive disorder in pregnant women. The angiogenic biomarkers, soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) ratio, have been shown to be associated with diagnosis and prediction of preeclampsia. The objective of this study is to validate the analytical performance of sFlt-1 and PlGF on the Cobas e602 system (Roche Diagnostics Corporation). Method Intra-day and inter-day precisions for both sFlt-1 and PlGF assays were assessed using quality control materials provided from Roche Diagnostics. The accuracies for both assays were assessed by running 60 patient samples, which have been previously analyzed on the Elecsys 411 analyzer (Roche Diagnostics Corporation) at the Beth Israel Deaconess Medical Center. Linearity studies for both assays were performed using patient plasma spiked with recombinant sFlt-1 and PlGF proteins (R&D systems). Hemolysis, icterus, lipemia and biotin interference studies were performed by spiking hemolysate, bilirubin, intralipid or biotin into either pooled patient plasma with detectable levels of sFlt-1 and PlGF or otherwise, patient plasma spiked with recombinant sFlt-1 and PlGF proteins. Results Total precisions for both assays demonstrated CVs of 0.98). Lower limit of quantitation (10% CV) was 30 pg/mL for sFlt-1 and 7 pg/mL for PlGF, respectively. Interference studies showed sFlt-1 and PlGF were not significantly affected by hemolysis up to H-indices of 500 and 1000 respectively; both assays were not affected by bilirubin up to an I-index of 60, and lipemia up to an L-index of 2800. Biotin at concentrations >30 ng/mL caused significant negative bias for both sFlt-1 and PlGF assays. Comparison studies showed the following: Cobas e602 sFLT-1 = 1.09 [Elecsys 411 sFLT-1] +203 (r2=0.97, Sy/x=1234, n=58); Cobas e602 PlGF = 1.10 [Elecsys 411 PlGF] +47 (r2=0.99, Sy/x=22.1, n=58); Cobas e602 sFLT-1/PlGF ratio = 0.94 [Elecsys 411 sFLT-1/PlGF ratio] +3.5 (r2=0.91, Sy/x=50, n=58). Conclusion sFlt-1 and PlGF measured on Roche Diagnostics Cobas e602 system demonstrated excellent analytical performance and are acceptable for clinical use once approved in the US.

Background There are considerable demands to accurately measure estradiol (E2) at low concentrations ( Methods A total of 290 μL of sample was mixed with internal standard (IS), E2-d4, and extracted with a mixture of hexane/ethyl acetate (90/10) (v/v). After extraction, sample was separated by Eksigent Ekspert™ micro LC 200 system with a flow rate of 35 μL/min in a total run time of 3.5 min and detected by SCIEX QTRAP 6500 mass spectrometer in a negative mode using transitions: 271/145 (quantifier) and 271/143 (qualifier). In this method, it was crucial to use HPLC columns with stability at a pH >10. Results The validation study demonstrated broad linear ranges (3.0–820.0 pg/mL) with r 2 > 0.999. Total precision was below 15% at all QC levels, and limit of quantification (LOQ) was 3.0 pg/mL. Our method showed good correlation with E2 RIA (r 2 = 0.96, bias = −1.0 pg/mL) and modest correlation with E2 Roche Cobas automated immunoassay (r 2 = 0.86, bias = 6.0 pg/mL). Conclusions In conclusion, we developed and validated a routinely applicable micro LC-MS/MS method without derivatization for E2 in blood samples with an LOQ of 3.0 pg/mL.

Background: CYP2D6 is a highly polymorphic phase I enzyme that metabolizes 20%–25% of clinically used drugs. The objective of this study was to validate a CYP2D6 genotyping assay with the NanoChip® Molecular Biology Workstation.Methods: We genotyped 200 anonymized human DNA samples with the Pyrosequencing® platform at the Medical College of Wisconsin and with the NanoChip platform at Dartmouth Medical School. We compared CYP2D6 genotypes and resolved samples with genotypic discrepancies with the Jurilab CYP2D6 duplication/deletion assay or with traditional DNA sequencing. The Jurilab assay is a long-range PCR assay used to evaluate sequence structures 3′ of the CYP2D7 and CYP2D6 coding regions. For the NanoChip platform, we performed multipad addressing and duplicate runs to test the intra- and intercartridge precision, within- and between-run precision, and reproducibility of the defined genotypes.Results: We used both platforms to genotype all 200 DNA samples for CYP2D6*3, *4, *5, *6, *7, *8, and gene duplication. The 2 methods showed 99.4% concordance in the genotyping results; we found only 8 discrepant genotypes among 1400 DNA analyses. Confirmatory molecular analysis of the discrepant genotypes revealed that the NanoChip assay showed better agreement. The imprecision of the NanoChip method (CV) was 8.9%–17.7%.Conclusions: This validation study of the NanoChip electronic microarray–based CYP2D6 genotyping assay revealed a CV

We describe a two-site time-resolved immunofluorometric assay for guinea pig vascular permeability factor (VPF) for quantifying VPF in different biological fluids. Antibody against the carboxy terminus (C-IgG) is immobilized on microtiter wells, and antibody against the amino terminus (N-IgG) is labeled with Eu(3+)-chelate. Line 10 tumor culture medium, known to be rich in VPF, is assayed in a two-step incubation. Bound Eu3+ is then quantified by dissociation into a fluorescent enhancement solution, with measurement of the time-resolved fluorescence. The analytical sensitivity is 0.35 VPF unit, and the intra-assay CV is about 20%. The assay is specific for VPF, because pre-treatment with the appropriate C- or N-peptide, or pre-extraction of VPF, greatly decreases fluorescence. The VPF immunoassay is highly correlated (r2 = 0.94) with the Miles permeability assay, the classical bioassay of VPF. In addition, the immunofluorometric assay is about 30-fold more sensitive than the Miles assay.

Objective: Assessment of platelet function testing is often limited when platelet counts are low, as typically found in pediatric and thrombocytopenic populations. We aim to develop a high sensitive method for measuring the release of endogenous serotonin by mass spectrometry to address this limitation. Methods: 100 μL citrated blood was diluted 10-fold to 1.0 mL with Modified HEPES/Tyrode Buffer (MTB). 80 μL of the diluted blood was then incubated with a platelet agonist, such as ADP, unstirred, …

The effects on immunoassays of heterophilic antibodies (HAs) in the plasma and serum have been well documented (1)(2)(3)(4)(5). The use of monoclonal mouse antibodies for radioimaging of tumors as well as in the treatment of some cancers often gives rise to human anti-mouse antibodies. HAs can also arise as a result of incidental or occupational exposure to foreign proteins, as in the case of veterinarians, farm workers, and food preparers, or by the presence of domestic animals in the home environment. The prevalence of HAs in the general population has been estimated to be as high as 40% (1). Typically, these antibodies are of the IgG class and recognize epitopes on the Fc portion of the foreign immunoglobulin, although instances where the epitope is located in the Fab region have been reported (6)(7). Additionally, the binding of these antibodies is not always species-specific, making it possible that antigens from two different species can be cross-linked. Although usually not clinically significant, the presence of high titers of these antibodies can lead to analytical errors in commonly used “sandwich” immunoassays by cross-linking the capture and label antibodies in the absence of specific analyte. Such cross-linking by HAs has been shown to lead to falsely increased CK-MB and CA125 (6)(7)(8). Most modern immunoassays contain nonspecific, “blocker” immunoglobulins originating from the same species as the analyte-specific antibodies in an attempt to limit the effect of HAs; however, the problem persists. We report here a 69-year-old man whose plasma and serum cardiac troponin I (cTnI) concentrations were falsely increased when measured using the Abbott AxSYM® cTnI assay. We demonstrate that HAs accounted for the falsely increased cTnI, and we suggest how to resolve such situations. A 69-year-old Caucasian man …

The diagnostic criteria for antiphospholipid syndrome include the presence of one or more typical clinical features plus one or more laboratory findings (1). The latter include positivity (on two or more occasions, ≥6 weeks apart) of either lupus anticoagulant or anticardiolipin antibody (ACA). We report inconsistencies among lots of anticardiolipin reagents from one supplier and suggest that the differences are related to changes in calibration materials that are also used by other suppliers of ACA reagents. Several, perhaps most, ACA ELISAs are calibrated with Harris “standards” (Louisville APL Diagnostics, Inc.) or secondary calibrators that are traceable to them. Recently, there has been a change in the latest generation of calibration materials, the LAPL-GM-200 calibrators for IgG and IgM ACA. When the latest LAPL-GM-200 calibrators were produced, the manufacturer attempted to make these new calibrators agree with …

In evaluating the EMIT system for vancomycin used in the Cobas Bio centrifugal analyzer, we found two potential problems, each of which may have important clinical ramifications. First, precision, though acceptable in concentrations up to 30 mg/L, was marginal in the range above 30 mg/L. Second, when EMIT values were compared with those by fluorescent polarization immunoassay (TDx), we found a good correlation but a significant proportional bias: [EMIT] = (0.877)[TDx] + 0.435 mg/L (r = 0.971). The proportional bias was much more pronounced in specimens with high creatinine values than in specimens with normal values for creatinine. It remains to be determined which method is more nearly accurate. This imprecision and proportional bias in specimens with increased creatinines lead us to conclude that the EMIT vancomycin system should be used with caution.