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* Context.--Moderna (mRNA-1272) and Pfizer (BNT162b2) SARS-CoV-2 vaccines demonstrate favorable safety and efficacy profiles, but direct comparison data are lacking. Objective.--To determine the vaccines' side effect profiles and expected antibody responses. These data may help personalize vaccine selection and identify individuals with a suboptimal vaccine response. Design.--One hundred forty-nine healthy, largely seronegative adults were assigned Moderna (n = 79) or Pfizer (n = 70). Following the second dose, participants completed a survey documenting their side effects. Serum was collected 0 to 4 days prior to dose 2, and 14 [+ or -] 4 days, 30 6 4 days, 90 [+ or -] 10 days, and 180 [+ or -] 20 days after dose 2. Convalescent serum specimens were collected 32 to 54 days from donors after a polymerase chain reaction-confirmed SARS-CoV-2 infection (n = 20). Anti-spike antibodies were measured using the Roche Diagnostics Elecys Anti-SARS-CoV-2 S assay on a Roche cobas e801 instrument. Results.--Participants receiving the Moderna vaccine experienced side effects with greater frequency and severity. Both vaccines elicited a robust antibody response, but median signal was higher in Moderna recipients. Symptom severity decreased with age. Antibody response in Pfizer recipients negatively correlated with age. Antibody response decreased after 6 months (84% reduction in Moderna, 79% Pfizer), but values remained greater than for convalescent donors. Antibody response did not correlate with gender or symptom severity. Conclusions.--Moderna may be preferred in individuals in need of greater immune stimulation (eg, older individuals), whereas Pfizer may be preferred in those concerned about vaccine reactions. Anti-spike antibody signal varies by vaccine, so specific reference intervals will be needed to identify individuals with a suboptimal response., Since its identification as the cause of a novel respiratory pneumonia first documented in Wuhan, China, in December 2019, SARS-CoV-2 has spread rapidly throughout the globe, causing 221 million confirmed [...]

Background: Loperamide (Imodium®), a commonly used anti-diarrheal, is a mu opioid receptor agonist that, like all opioids, reduces gastrointestinal tract peristalsis. Loperamide is considered to have low abuse potential as it does not produce an analgesic or euphoric effect due to low bioavailability and first-pass metabolism. However, reports of individuals misusing loperamide through the use of super-therapeutic doses, alone or in combination with P-glycoprotein and/or CYP450 enzyme inhibitors, is increasing. We hypothesized that loperamide could potentially cross-react with laboratory immunoassay drug screens. Methods: Drug-free urine was spiked with loperamide or its principal metabolite, N-desmethyl loperamide (dLop), and assayed on multiple fentanyl and buprenorphine assays. Fentanyl immunoassay screen-positive results at one institution were examined by high-resolution mass spectrometry (MS) for the presence of loperamide and quantified by liquid chromatography– tandem MS when positive. Results: Loperamide produced positive results on the Thermo DRI Fentanyl and Immunalysis Fentanyl assays at concentrations greater than 5.72 mg/L and 23.7 mg/L. dLop generated positive results for the Thermo DRI and Immunalysis fentanyl assays at concentrations exceeding 6.9 mg/L and 35.7 mg/L. dLop also produced positive buprenorphine results on the Thermo CEDIA buprenorphine assay at concentrations exceeding 12.2 mg/L. High-resolution MS analysis of 225 fentanyl immunoassay positives (Thermo DRI) yielded 5 specimens containing loperamide and/or dLop, 4 of which contained measurable quantities of fentanyl in addition to loperamide/dLop. Conclusions: Laboratories using these assays should be aware of the potential for false-positive screening results due to the presence of high concentrations of loperamide and its metabolite dLop. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to redefine the icterus index cutoff for the Roche Jaffé creatinine method using both conjugated and unconjugated bilirubin on 3 Roche cobas modules (c311, c501, and c701/c702) at laboratories across our hospital network. Methods: Interference was evaluated by adding conjugated bilirubin (as bilirubin conjugate, ditaurate) and unconjugated bilirubin to pooled remnant plasma. The effects of conjugated and unconjugated bilirubin were tested separately to assess the contribution of each species. The magnitude of interference was calculated as both absolute and percentage error with total allowable error limits set at 0.1 mg/dL (8 µmol/L or 8%). Results: Analysis of interference data across the 3 Roche modules did not show bias exceeding our total allowable error limits for plasma creatinine up to a conjugated bilirubin icterus index of 16.2 (approximately 16.2 mg/dL or 277 μmol/L) or an unconjugated bilirubin icterus index of 18.5 (approximately 18.5 mg/dL or 316 μmol/L), the highest concentrations tested. Conclusions: Our results demonstrate that the Roche Jaffé method exhibits acceptable performance in the presence of icterus at icterus indexes above the manufacturer's current recommendations of 5 (approximately 5 mg/dL or 86 μmol/L) and 10 (approximately 10 mg/dL or 171 μmol/L) for conjugated and unconjugated bilirubin, respectively. We have updated the icterus index in our hospital system to 16 for conjugated bilirubin and 18 for unconjugated bilirubin. [ABSTRACT FROM AUTHOR]

Background: Autoimmune encephalitis (AE) is a rare collection of disorders that present with a diverse and often nebulous set of clinical symptoms. Indiscriminate use of multi-antibody panels decreases their overall utility and predictive value. Application of a standardized scoring system may help reduce the number of specimens that generate misleading or uninformative results. Methods: The results of autoimmune encephalopathy, epilepsy, or dementia autoantibody panels performed on serum (n = 251) or cerebrospinal fluid (CSF) (n = 235) specimens from October 9th, 2016 to October 11th, 2019 were collected. Retrospective chart review was performed to calculate the Antibody Prevalence in Epilepsy and Encephalopathy (APE2) score for patients with an antibody above the assay-specific reference interval and to classify results as true or false positive. Results: Of the 486 specimens, 60 (12.3%) generated positive results for any AE antibody (6 CSF and 54 serum). After removing 2 duplicate specimens collected from a single patient, 10 of the remaining 58 were determined to be true positives and 8 contained neural-specific antibodies. Application of the APE2 score revealed that 89% of all true positives and 86% of specimens with neural-specific antibodies had a score ≥4. In contrast, 76% of false positives, 74% of clinically nonspecific antibodies, and 85% of the negative specimens had an APE2 score <4. Conclusion: The APE2 score can improve the diagnostic utility of autoimmune encephalopathy evaluation panels. [ABSTRACT FROM AUTHOR]

In recent years, there has been renewed interest in the "old" average of normals concept, now generally referred to as moving average quality control (MA QC) or patient-based real-time quality control (PBRTQC). However, there are some controversies regarding PBRTQC which this review aims to address while also indicating the current status of PBRTQC. This review gives the background of certain newly described optimization and validation methods. It also indicates how QC plans incorporating PBRTQC can be designed for greater effectiveness and/or (cost) efficiency. Furthermore, it discusses controversies regarding the complexity of obtaining PBRTQC settings, the replacement of iQC, and software functionality requirements. Finally, it presents evidence of the added value and practicability of PBRTQC. Recent developments in, and availability of, simulation methods to optimize and validate laboratory-specific PBRTQC procedures have enabled medical laboratories to implement PBRTQC in their daily practice. Furthermore, these methods have made it possible to demonstrate the practicability and added value of PBRTQC by means of two prospective "clinical" studies and other investigations. Although internal QC will remain an essential part of any QC plan, applying PBRTQC can now significantly improve its performance and (cost) efficiency. [ABSTRACT FROM AUTHOR]

The quest to use patient results as quality control for routine clinical chemistry testing has long been driven by issues of the unavailability and cost of suitable quality control material and the matrix effects of synthetic material. Hematology laboratories were early adopters of average of normals techniques, primarily because of the difficulty in acquiring appropriate, stable quality control material, while in the chemistry laboratories, the perceived advantages and availability of synthetic material outweighed the disadvantages. However, the increasing volume of testing in clinical chemistry plus the capability of computer systems to deal with large and complex calculations has now made the use of patient-based quality control algorithms feasible. The desire to use patient-based quality control is also driven by increasing awareness that common quality control rules and frequency of analysis may fail to detect clinically significant assay biases. The non-commutability of quality control material has also become a problem as laboratories seek to harmonize results across regions and indeed globally. This review describes the history of patient-based quality control in clinical chemistry, summarizes the various approaches that can be implemented by laboratory professionals, and discusses how patient-based quality control can be integrated with traditional quality control techniques. [ABSTRACT FROM AUTHOR]

Patient-based real-time quality control (PBRTQC) is a laboratory tool for monitoring the performance of the testing process. It includes well-established procedures like Bull's algorithm, average of nomals, moving median, moving average (MA) and exponentially (weighted) MAs. Following the setup and optimization processes, a key step prior to the routine implementation of PBRTQC is the verification and documentation of the performance of the PBRTQC as part of the laboratory quality system. This verification process should provide a realistic representation of the performance of the PBRTQC in the environment it is being implemented in, to allow proper risk assessment by laboratory practitioners. This document focuses on the recommendation on performance verification of PBRTQC prior to implementation. [ABSTRACT FROM AUTHOR]

Background: Laboratory tests that use streptavidin--biotin binding mechanisms have the potential to be affected by high circulating biotin concentrations, which would produce positive and negative interference in biotinylated competitive and noncompetitive (sandwich) immunoassays, respectively. Consumption of high-dose biotin supplements for cosmetic or health-related reasons has drawn attention to biotin interference in clinical laboratory tests. Case reports and in vivo studies show that ingestion of supplemental biotin can cause clinically signifi- cant errors in select biotinylated immunoassays. Content: This AACC Academy document is intended to provide guidance to laboratorians and clinicians for preventing, identifying, and dealing with biotin interference. In vivo and in vitro spiking studies have demonstrated that biotin concentrations required to cause interference vary by test and by manufacturer. This document includes discussion of biotin's mechanisms for interference in immunoassays, pharmacokinetics, and results of in vitro and in vivo studies and cites examples of assays known to be affected by high biotin concentrations. This document also provides guidance recommendations intended to assist laboratories and clinicians in identifying and addressing biotin interference in laboratory testing. Summary: The recent increase in the use of high-dose biotin supplements requires laboratorians and clinicians to be mindful of the potential for biotin interference in biotinylated immunoassay-based laboratory tests. Laboratories, clinicians, regulators, and patients should work together to ensure accurate laboratory results. Laboratories have several options for identifying suspected biotin interference in specimens. Alternatively, the relatively fast elimination of biotin allows the potential for rapid follow-up specimen analysis if necessary. [ABSTRACT FROM AUTHOR]

Background: Rapid identification and quantification of toxic alcohols and ethylene glycol is imperative for appropriate treatment. Clinical laboratories frequently rely on direct injection gas chromatography (GC) methods, but these methods require inlet maintenance and multiple GC systems. To overcome these challenges, we developed a single-column headspace GC method for both toxic alcohols and glycols that streamlines patient sample analysis for toxic alcohol ingestion. Methods: Optimal parameters for nonderivatized (volatile) and derivatized (glycol) plasma samples were determined using a 7890 A headspace sampler, an Agilent 7697 A GC system, a DB-200 column, and a flame ionization detector. Limit of Quantification (LoQ), linearity, imprecision, carry-over, method comparison, and interference studies were performed using quality control materials and prepared plasma samples. Results: Our volatile method is linear to 3000mg/L (ethanol) with LoQ concentrations below 20 mg/L (ethanol). The glycol method is linear to 2000 mg/L (ethylene glycol) with LoQ concentrations below 40 mg/L (ethylene glycol). Total assay impression ranged from 1.7% for ethanol to 13.3% for propylene glycol. Both methods were free of sample carryover and compared favorably with a similar clinical method at an outside laboratory. Propionic acid, an accumulating metabolite in methylmalonic acidemia that interferes with ethylene glycol identification by a different method, did not interfere with the ethylene glycol method reported here. Conclusions: Our single-column headspace GC method provides reliable, robust, and rapid identification and quantification of commonly encountered toxic alcohols. Clinical laboratories relying on direct injection Gas Chromatography (GC) for toxic alcohol analysis face challenges including frequent inlet maintenance, sample carryover, or the need for separate GC systems for volatile and glycol analysis. We summarize our development and optimization of two headspace GC methods for nonderivatized (volatile) and derivatized (glycol) plasma samples that use a single DB-200 analytical column. These methods are comparable to other GC methods, not prone to sample carryover, eliminate the need for multiple GC systems or columns, and are readily applicable to other laboratories that provide toxic alcohol analysis. [ABSTRACT FROM AUTHOR]

Background: Graves disease is caused by autoantibodies that target the thyroid-stimulating hormone receptor (TSHR). Anti-TSHR autoantibody measurement is routinely performed to differentiate between Graves disease and other causes of hyperthyroidism. We evaluated the clinical performance of a reference laboratory bioassay [the Thyretain thyroid-stimulating immunoglobulin (TSI) Bioassay by Diagnostic Hybrids] and 2 commercially available immunoassays: the TSI Bridge immunoassay by Siemens and the thyroid-stimulating hormone receptor antibody (TRAb) immunoassay by Roche. We further evaluated the analytical performance of the Siemens TSI and Roche TRAb assays. Methods: We performed method comparisons using 125 patient specimens submitted for TSI testing for clinical purposes. Concordance of patient results was assessed between the 3 methods, and chart review was performed to further evaluate samples that generated discordant results. All 3 methods were also evaluated for potential interference caused by human chorionic gonadotropin (hCG). Results: The Roche and Siemens assays demonstrated acceptable day-to-day precision, within-run precision, and precision at the clinical decision cutoffs. Despite manufacturer-defined analytical measuring ranges up to 40 IU/L, the Roche and Siemens assays were linear to 20 IU/L and 15 IU/L, respectively. hCG concentrations up to 150000 IU/L did not interfere with any of the methods evaluated. Moderate agreement between methods was observed when testing patient specimens that generated negative (≤1.3) or weakly positive (1.4-3.8) results by the Thyretain assay. One hundred percent agreement was observed when the Thyretain assay was strongly positive (≥3.9). Conclusions: The 3 commercially available anti-TSHR autoantibody measurement methods demonstrated equivalent performance in patients with untreated Graves disease. Discordant results were observed when testing specimens collected from patients undergoing treatment for Graves disease. In these patients, the Siemens TSI assay more frequently generated results consistent with clinical history, results of other laboratory tests, and imaging studies than the Thyretain Bioassay and Roche TRAb assay. [ABSTRACT FROM AUTHOR]

Background: Our study objective was to validate 2 individual methods to measure α-fetoprotein (AFP) and human chorionic gonadotropin (hCG) in cerebrospinal fluid (CSF) on the Roche cobas® 6000 analyzer. A 3-year retrospective chart review of CSF samples analyzed for AFP and hCG was also conducted. Methods: Serum samples with high concentrations of AFP or hCG were added to aliquots of pooled CSF. Precision, linearity, detection limit, recovery, carryover, stability, and interference studies of the AFP and hCG+β assays were performed. Results: Within-day and day-to-day assay imprecision for AFP and hCG assays were <5% at all concentrations tested. The linear range of the AFP assay was established as 1.0-1100 μg/L, and limit of quantification (LOQ) was <1.0 μg/L. The linear range of the hCG assay was established as 1.0-9500 IU/L and LOQ 0.7 IU/L. There was no demonstrable matrix effect, and neither assay was affected by the presence of hemolysis or xanthochromia. AFP in CSF was stable at room and refrigerated temperatures for up to 48 h at concentrations of 19 and 306 μg/L but increased by 24 h at a concentration of 908 μg/L. AFP in CSF was stable frozen (-20 °C) for up to 7 days. hCG in CSF at all concentrations tested was stable at room, refrigerated, and frozen temperatures for up to 7 days. Conclusions: The Roche cobas 6000 AFP and hCG+β assays accurately quantify AFP and hCG in CSF, facilitating rapid and accurate diagnosis as well as monitoring of intracranial germ cell tumors. [ABSTRACT FROM AUTHOR]

The dopamine transporter (DAT) is an integral membrane protein located in dopamine-producing neurons and is responsible for clearing the synapse of secreted dopamine (DA) following neural depolarization and synaptic release. [...]

Introduction: The dopamine transporter (DAT) is an integral membrane protein located in dopamine producing neurons and is responsible for clearing the synapse of secreted dopamine (DA) following neural depolarization and [...]

The authors support the recommendation by the U.S. Centers for Disease Control and Prevention to discontinue zinc protoporphyrin (ZPP) as a surrogate test for lead screening in pediatric patients. Topics include the ease of use of ZPP, review of 602 pairs of lead and ZPP patient results on patients from six months to 16-years old collected between January 2012 and December 2016, and review of results of 19 patients who underwent multiple blood lead and ZPP tests.

Conversion of clopidogrel (Plavix) to its active metabolite is catalyzed largely by the P450 enzyme 2C19 (CYP2C19). Numerous allelic variants of CYP2C19 exist. The *1 allele is considered wild type, whereas the *2 and *3 alleles have no in vivo enzymatic activity. Conversely, the *17 allele has increased expression, resulting in increased clopidogrel activation. Poor metabolizers (*2/*2 and *2/*3 genotypes) experience higher rates of therapeutic failure. For this reason, we have validated a CYP2C19 genotyping assay for the *1, *2, *3, and *17 alleles. Genomic DNA extracted from 30 deidentified EDTA whole-blood samples from patients was analyzed at 2 independent facilities using specific TaqMan real-time polymerase chain reaction primers and probes. Concordant genotypes were generated on all samples tested. Of the 30 samples, 15 were CYP2C19*1/*1, 8 were CYP2C19*1/*17, 5 were CYP2C19*1/*2, and 2 were CYP2C19*2/*17. There were no CYP2C19*3 alleles or *2/*2 homozygous genotypes detected. This CYP2C19 genotyping assay is appropriate for clinical testing, demonstrating excellent interlaboratory concordance, enabling the selection of the most effective clopidogrel treatment regimen for patients undergoing percutaneous coronary intervention. [ABSTRACT FROM AUTHOR]

Background Macroenzyme complexes of serum enzymes and antibody can increase the circulating enzymatic activity and may lead to unnecessary additional testing and procedures. Laboratory physicians and scientists need to be aware of techniques to identify macroenzyme complexes when suspected. Case report To investigate the possibility of a macro-alkaline phosphatase in the serum of a 74 year old male with persistently increased alkaline phosphatase we coupled a protein A/G agarose affinity chromatography technique with isoenzyme electrophoresis to look for the presence of macro-alkaline phosphatase. Results The majority of the alkaline phosphatase activity in the patient's serum sample was bound to the column and only a minor fraction (25%) of alkaline phosphatase activity was present in the column flow-through. The alkaline phosphatase activity was also found to co-elute with the immunoglobulins in the patient sample. The alkaline phosphatase activity in a control serum sample concurrently treated in the same manner did not bind to the column and was found in the column flow-through. Conclusion The use of protein A/G agarose affinity chromatography is a rapid and simple method that can be applied to the investigation of other macro-enzyme complexes. [ABSTRACT FROM AUTHOR]