Xylazine in an anesthetic drug used for the sedation of animals and increasingly appearing as an adulterant in uncontrolled drug supplies, primarily illicit fentanyl. The ability to detect xylazine exposure by urine drug testing may improve monitoring of this drug trend and our understanding of the effects and risks associated with xylazine exposure. Currently, limited information is available regarding the elimination of xylazine or its metabolites in humans. In this study, we report quantification of xylazine and 4-hydroxy-xylazine (4-OH-x) in hydrolyzed urine specimens collected from 109 patients testing positive for fentanyl and xylazine using liquid chromatography tandem mass spectrometry (LC-MS/MS). 4-hydroxy-xylazine was a minor urinary metabolite in most patients with a median metabolite-to-xylazine (MR) concentration ratio 0.09. Additional urinary metabolites were identified including oxo-xylazine (oxo-x), OH-oxo-xylazine (OH-oxo-x), OH-sulfone-xylazine (OH-sulfone-x), and sulfone-xylazine (sulfone-x), with median MR peak area ratios of < 0.01, 0.60, 0.30, and 1.60, respectively. Sulfone-x signal exceeded that of xylazine in more than 70% of urine specimens. Sulfone-x is not glucuronidated and does not appear to form positional isomers. Additional studies are needed to examine whether detection of xylazine metabolites may improve the sensitivity and/or extend the detection time window for xylazine exposure.

Background:Xylazine has been increasingly linked to human overdose deaths. No antidote has been identified and naloxone cannot reverse the effect of xylazine. Xylazine withdrawal is not alleviated by opioids. It is imperative to detect xylazine when treating overdoses. No screening method for xylazine has been approved by FDA. We aim to develop a rapid and high sensitivity xylazine test for clinical urine testing. Methods:Monoclonal antibodies with high sensitivity and specificity against xylazine were developed. The leading clone was used to develop a competitive lateral flow immunoassay. The analytical cutoff, specificity and clinical performance of this test was characterized using standards in drug-free urine and clinical urine samples. Results:The rapid xylazine dipstick test has a test time of 5 minutes, and a cutoff of 10 ng/mL xylazine in drug-free urine. No cross reactivity with other commonly used drugs or endogenous metabolites were observed, except for 3% cross reactivity with clonidine. In 181 mass spectrometry confirmed clinical urine samples with xylazine concentrations > 10 ng/mL and 120 urine samples with xylazine concentrations <10 ng/mL, the dipstick demonstrated a clinical sensitivity of 100% and a clinical specificity of 97%. All 4 false positives had combined xylazine and 4-hydroxy-xylazine concentrations in the 5-10 ng/mL range, with additional xylazine metabolites detected by mass spectrometry. Conclusions:When used with 10 ng/mL cutoff, the rapid xylazine dipstick demonstrates high clinical sensitivity and clinical specificity in urine samples, compared to gold standard mass spectrometry methods. This novel test has the potential to enable informed clinical decisions in suspected xylazine overdoses.

Xylazine is a veterinary sedative that is frequently detected in the illicit drug supply, often found mixed with illicitly manufactured fentanyl (IMF). It has been detected in the blood of overdose victims and patients who use illicit drugs. Xylazine is not approved for use in humans. It is an alpha-2-adrenergic receptor agonist that causes deep sedation that is non-responsive to naloxone, the antidote for opioid overdose. Chronic exposure to xylazine has been linked to severe wounds that can progress to amputation. Medetomidine is another related veterinary sedative that has more recently emerged as an adulterant in IMF. Medetomidine is also an alpha-2-adrenergic agonist, and in veterinary medicine it is known to be significantly more potent than xylazine. The mixture of these drugs with IMF complicates the treatment of patients exposed to these drugs. Wider availability of analytical methods to detect xylazine, and now medetomidine, is crucial for responding to these health threats and increasing knowledge on the harms and potential therapies for exposed patients. This review covers what is currently known about these drugs, including observed concentrations in various biospecimens, expected major metabolites and windows of detection, and available analytical approaches for detecting exposure.

Illicitly manufactured fentanyl and fentanyl analogs have led to a drastic increase in opioid related overdose deaths. Sensitive detection of fentanyl exposure requires specific assays that target fentanyl and its major metabolite norfentanyl. Fentanyl immunoassays have varying sensitivity to detect fentanyl analogs but many of the more prevalent analogs are not detected by routine fentanyl testing methods. This review focuses on the current state of both immunoassay and mass spectrometry-based testing methods for the detection of fentanyl and fentanyl analogs.

OBJECTIVES:Xylazine has been increasingly identified in human overdose deaths. Detection of xylazine in clinical urine samples has clinical utility when treating overdoses. No screening method for xylazine has been approved by the US Food and Drug Administration (FDA). We aim to develop and validate a rapid and high sensitivity xylazine test for clinical urine testing. METHODS:Monoclonal antibodies with high sensitivity and specificity against xylazine were developed. The leading clone was used to develop a competitive lateral flow immunoassay. The analytical cutoff, specificity, and clinical performance of this test was characterized using standards in drug-free urine and clinical urine samples. RESULTS:The rapid xylazine dipstick test has a test time of 5 minutes and a cutoff of 10 ng/mL xylazine in drug-free urine. No cross reactivity with other commonly used drugs or endogenous metabolites were observed, except for 3% cross reactivity with clonidine. In 190 mass spectrometry confirmed clinical urine samples with xylazine concentrations ≥10 ng/mL and 168 urine samples with xylazine concentrations <10 ng/mL, the dipstick demonstrated a clinical sensitivity of 100% and a clinical specificity of 98%. All 4 false positives had combined xylazine and 4-hydroxy-xylazine concentrations in the 5-10 ng/mL range, with additional xylazine metabolites detected by mass spectrometry. CONCLUSIONS:When used with 10 ng/mL cutoff, the rapid xylazine dipstick demonstrates high clinical sensitivity and clinical specificity in urine samples, compared with gold standard mass spectrometry methods. This novel test has the potential to enable informed clinical decisions in cases with suspected xylazine exposure.

Current guidelines recommend universal screening for substance use disorders in obstetric patients, and neonatal drug testing is also frequently performed. Meconium is often the preferred specimen type to detect neonatal drug exposure due to a longer window of detection compared to urine, but most laboratories send out meconium testing to specialized reference laboratories, which can delay results for several days or more. Here, we evaluate a rapid and definitive liquid chromatography tandem mass spectrometry method for neonatal urine drug testing and compare results obtained using this method to paired meconium drug testing in 1,424 neonates for amphetamines, cocaine, cannabinoids, opiates, oxycodone and phencyclidine. Urine testing showed equivalent sensitivity to current meconium methods for detecting in utero exposure to amphetamines and cocaine.

Abstract Background Doctoral-level clinical chemists (also termed clinical biochemists) have unique, broad roles in laboratory medicine spanning numerous clinical specialties. However, the full scope of responsibilities for a clinical chemist is not well understood, and institutional recognition and support varies. We sought to better understand the roles and responsibilities of practicing clinical chemists through distribution of an online survey designed to examine work-related responsibilities and other key factors related to job satisfaction. Survey results demonstrate the value of clinical chemists and can be used to promote parity within the profession. Methods Survey data was collected for 5 weeks from 10/10/2022-11/14/2022. The survey was targeted towards individuals holding doctoral level degrees (MD, PhD or MD/PhD), and consisted of 41 questions related to demographics, compensation, duties/responsibilities, and institutional support. Data analysis focused on responses from full-time clinical chemists located in the US and Canada (n=223/298 total respondents). Results Survey responses included male (n=109) and female (n=109) clinicians from all career stages (early <10y, n=101; mid 10-20y, n=63; late >20y, n=59). Clinical chemistry was the primary specialty reported (69%), followed by clinical pathology (16%), with 55% of responses reporting more than one specialty of practice, most often toxicology (21%). Multiple institution types (academic, community, reference laboratory, other) and academic career tracks (clinical, education, research, other) were represented; Most respondents were based in an academic hospital laboratory (n=131/223). Self-reported daily working hours varied by gender, years in practice, job duties and institutional setting; Females reported working more hours than males, working hours increased with years in practice, and the academic hospital setting reported the longest working hours, as did those on an ‘Education’ track. Responsibilities were quantified based on time spent per week; Clinical service represented the greatest time spent per week (majority result, 20-40h/week), followed by administrative (1-20h/week), research (<1-10h/week), teaching (<1-10h/week) and CE (<1-10h/week) duties. Support for clinical responsibilities was assessed further; 69% of respondents felt they had adequate time to perform clinical responsibilities, 55% reported access to adequate resources to perform clinical responsibilities and 51% reported feeling ‘Moderately’ or ‘Very’ stressed by clinical workload assignment. Top reasons for feeling overwhelmed included ‘Understaffing or inadequate support staff’ (n=113 responses), ‘Increased volume of work or caseload’ (n=73 responses) and ‘Lack of IT support to make necessary changes/improvements’ (n=70 responses). Resource quality was individually rated; Medical technologists, research technologists/scientists, LIS support and research support received a ‘Less than adequate’ rating by the majority of respondents, while compensation, administrative support and equipment received majority ‘Adequate’ ratings. Conclusions Clinical chemists work in a wide range of healthcare settings with unique career tracks, although the majority of work hours are devoted to provision of clinical service regardless of role definition. Most or all prioritize clinical work due to limited resources, which can limit research time and academic contributions. Clinical responsibilities are tied to feelings of stress and overwhelm in more than half of the survey population and could be reduced with improved quality and/or quantity of staff support.

BACKGROUND: The increasing prevalence of xylazine in the illicit drug supply is a growing concern for major health consequences in individuals who use fentanyl mixed with xylazine, but limited data are available regarding the pharmacokinetics of xylazine in humans. METHODS: Xylazine was quantified in serial remnant plasmas collected from 28 patients starting at the initial patient encounter and continuing for up to 52 h from presentation, using LC-MS/MS to calculate the terminal half-life for xylazine. Xylazine metabolites were identified by product ion scanning, and multiple reaction monitoring was used to estimate the relative abundance of xylazine metabolites in 74 collected plasma samples. RESULTS: The median terminal half-life for xylazine was calculated to be 12.0 h (range: 5.9-20.8). Oxo-xylazine and sulfone-xylazine metabolites were detected in all plasma specimens that contained xylazine. CONCLUSIONS: The half-life of xylazine in humans is longer than previously observed in animal studies, which furthers the current understanding of the expected duration of effects in individuals who use fentanyl mixed with xylazine and the window of detection. Both oxoxylazine and sulfone-xylazine appear to circulate in plasma for as long as xylazine.

BackgroundAs diagnostic tests for COVID-19 were broadly deployed under Emergency Use Authorization, there emerged a need to understand the real-world utilization and performance of serological testing across the United States. MethodsSix health systems contributed electronic health records and/or claims data, jointly developed a master protocol, and used it to execute the analysis in parallel. We used descriptive statistics to examine demographic, clinical, and geographic characteristics of serology testing among patients with RNA positive for SARS-CoV-2. ResultsAcross datasets, we observed 930,669 individuals with positive RNA for SARS-CoV-2. Of these, 35,806 (4%) were serotested within 90 days; 15% of which occurred <14 days from the RNA positive test. The proportion of people with a history of cardiovascular disease, obesity, chronic lung, or kidney disease; or presenting with shortness of breath or pneumonia appeared higher among those serotested compared to those who were not. Even in a population of people with active infection, race/ethnicity data were largely missing (>30%) in some datasets-limiting our ability to examine differences in serological testing by race. In datasets where race/ethnicity information was available, we observed a greater distribution of White individuals among those serotested; however, the time between RNA and serology tests appeared shorter in Black compared to White individuals. Test manufacturer data was available in half of the datasets contributing to the analysis. ConclusionOur results inform the underlying context of serotesting during the first year of the COVID-19 pandemic and differences observed between claims and EHR data sources-a critical first step to understanding the real-world accuracy of serological tests. Incomplete reporting of race/ethnicity data and a limited ability to link test manufacturer data, lab results, and clinical data challenge the ability to assess the real-world performance of SARS-CoV-2 tests in different contexts and the overall U.S. response to current and future disease pandemics.

Background Real-world performance of COVID-19 diagnostic tests under Emergency Use Authorization (EUA) must be assessed. We describe overall trends in the performance of serology tests in the context of real-world implementation. Methods Six health systems estimated the odds of seropositivity and positive percent agreement (PPA) of serology test among people with confirmed SARS-CoV-2 infection by molecular test. In each dataset, we present the odds ratio and PPA, overall and by key clinical, demographic, and practice parameters. Results A total of 15,615 people were observed to have at least one serology test 14–90 days after a positive molecular test for SARS-CoV-2. We observed higher PPA in Hispanic (PPA range: 79–96%) compared to non-Hispanic (60–89%) patients; in those presenting with at least one COVID-19 related symptom (69–93%) as compared to no such symptoms (63–91%); and in inpatient (70–97%) and emergency department (93–99%) compared to outpatient (63–92%) settings across datasets. PPA was highest in those with diabetes (75–94%) and kidney disease (83–95%); and lowest in those with auto-immune conditions or who are immunocompromised (56–93%). The odds ratios (OR) for seropositivity were higher in Hispanics compared to non-Hispanics (OR range: 2.59–3.86), patients with diabetes (1.49–1.56), and obesity (1.63–2.23); and lower in those with immunocompromised or autoimmune conditions (0.25–0.70), as compared to those without those comorbidities. In a subset of three datasets with robust information on serology test name, seven tests were used, two of which were used in multiple settings and met the EUA requirement of PPA ≥87%. Tests performed similarly across datasets. Conclusion Although the EUA requirement was not consistently met, more investigation is needed to understand how serology and molecular tests are used, including indication and protocol fidelity. Improved data interoperability of test and clinical/demographic data are needed to enable rapid assessment of the real-world performance of in vitro diagnostic tests.

INTRODUCTION:Ethylene glycol (EG) is a frequently considered toxicant in poisoned patients. Definitive diagnosis relies on gas chromatography (GC), but this is unavailable at most hospitals. A glycerol dehydrogenase (GDH)-based assay rapidly detects EG. A rapid turnaround time and wide availability of necessary instrumentation suggest this method could facilitate the rapid detection of EG.METHODS:This is a prospective, observational analysis of banked, remnant serum samples submitted to the laboratory of a large, multi-hospital healthcare system. Samples were submitted over a 12-month period for the explicit purpose of testing for suspected EG ingestion. All samples underwent GC and the GDH-based assay.RESULTS:Of the 118 analyzed samples, 88 had no EG detected by GC, and 30 were "positive." At the manufacturer's threshold of 6 mg/dL EG, there was 100% (95%CI; 88.7-100) positive percent agreement (PPA) and 98% (92.1-99.6) negative percent agreement (NPA). Adjusted to a threshold of 9 mg/dL, both the PPA and NPA were 100%. Deming regression of the observed concentrations revealed a slope of 1.16 (1.01 to 1.32) and intercept of -5.3 (-8.9 to -1.7).CONCLUSIONS:The GDH assay provides a sensitive and specific method for the detection and quantification of EG that is comparable to a GC-based method. More widespread use of this rapid, inexpensive assay could improve the care of patients with suspected toxic alcohol exposure. Further study is needed to evaluate the test performance in real-time patient treatment decisions.

Objectives: Recently, an estradiol immunoassay manufacturer (Beckman Coulter, USA) issued an ‘important product notice’ alerting clinical laboratories that their assay (Access Sensitive Estradiol) was not indicated for patients undergoing exogenous estradiol treatment. The objective of this analysis was to evaluate immunoassay bias relative to liquid chromatography tandem mass spectrometry (LC-MS/MS) in transgender women and to examine the influence of unconjugated estrone on measurem ents. Design: Cross-sectional secondary analysis. Methods: Estradiol concentrations from 89 transgender women were determined by 3 immunoassays (Access Sensitive Estradiol (‘New BC’) and Access Estradiol assays (‘Old BC’), Beckman Coulter; Estradiol III assay (‘Roche’), Roche Diagnostics) and LC-MS/MS. Bias was evaluated with and without adjustment for estrone concentrations. The number of participants who shifted between three estradiol concentration ranges for each immunoassay vs LC-MS/MS (>300 pg/mL, 70–300 pg/mL, and <70 pg/mL) was calculated. Results: The New BC assay had the largest magnitude overall bias (median: −34%) and was −40%, −22%, and −10%, among participants receiving tablet, patch, or injection preparations, respectively. Overall bias was −12% and +17% for the Roche and Old BC assays, respectively. When measured with the New BC assay, 18 participants shifted to a lower estradiol concentration range (vs 9 and 10 participants based on Roche or Old BC assays, respectively). Adjustment for estrone did not minimize bias. Conclusions: Immunoassay measurement of estradiol in transgender women may lead to falsely decreased concentrations that have the potential to affect management. A multidisciplinary health care approach is needed to ensure if appropriate analytical methods are available.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serosurveys can estimate cumulative incidence for monitoring epidemics, requiring assessment of serologic assays to inform testing algorithm development and interpretation of results. We conducted a multilaboratory evaluation of 21 commercial high-throughput SARS-CoV-2 serologic assays using blinded panels of 1,000 highly characterized specimens. Assays demonstrated a range of sensitivities (96%-63%), specificities (99%-96%), and precision (intraclass correlation coefficient 0.55-0.99). Durability of antibody detection was dependent on antigen and immunoglobulin targets; antispike and total Ig assays demonstrated more stable longitudinal reactivity than antinucleocapsid and IgG assays. Assays with high sensitivity, specificity, and durable antibody detection are ideal for serosurveillance, but assays demonstrating waning reactivity are appropriate for other applications, including correlation with neutralizing activity and detection of anamnestic boosting by reinfections. Assay performance must be evaluated in context of intended use, particularly in the context of widespread vaccination and circulation of SARS-CoV-2 variants.

Background Early evaluations of healthcare professional (HCP) COVID-19 risk occurred during insufficient personal protective equipment and disproportionate testing, contributing to perceptions of high patient-care related HCP risk. We evaluated HCP COVID-19 seropositivity after accounting for community factors and coworker outbreaks. Methods Prior to universal masking, we conducted a single-center retrospective cohort plus cross-sectional study. All HCP (1) seen by Occupational Health for COVID-like symptoms (regardless of test result) or assigned to (2) dedicated COVID-19 units, (3) units with a COVID-19 HCP outbreak, or (4) control units from 01/01/2020 to 04/15/2020 were offered serologic testing by an FDA-authorized assay plus a research assay against 67 respiratory viruses, including 11 SARS-CoV-2 antigens. Multivariable models assessed the association of demographics, job role, comorbidities, care of a COVID-19 patient, and geocoded socioeconomic status with positive serology. Results Of 654 participants, 87 (13.3%) were seropositive; among these 60.8% (N = 52) had never cared for a COVID-19 patient. Being male (OR 1.79, CI 1.05–3.04, p = 0.03), working in a unit with a HCP-outbreak unit (OR 2.21, CI 1.28–3.81, p < 0.01), living in a community with low owner-occupied housing (OR = 1.63, CI = 1.00–2.64, p = 0.05), and ethnically Latino (OR 2.10, CI 1.12–3.96, p = 0.02) were positively-associated with COVID-19 seropositivity, while working in dedicated COVID-19 units was negatively-associated (OR 0.53, CI = 0.30–0.94, p = 0.03). The research assay identified 25 additional seropositive individuals (78 [12%] vs. 53 [8%], p < 0.01). Conclusions Prior to universal masking, HCP COVID-19 risk was dominated by workplace and community exposures while working in a dedicated COVID-19 unit was protective, suggesting that infection prevention protocols prevent patient-to-HCP transmission. Article summary Prior to universal masking, HCP COVID-19 risk was dominated by workplace and community exposures while working in a dedicated COVID-19 unit was protective, suggesting that infection prevention protocols prevent patient-to-HCP transmission.

This cohort study examines the sensitivity of antibody tests to detect previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by time, test, sex, and age.

A Patient in Need of a Red Cell Exchange? Ingrid Perez-Alvarez, Ingrid Perez-Alvarez Department of Pathology and Laboratory Medicine, University of California Irvine School of Medicine, Orange, CA Search for other works by this author on: Oxford Academic Google Scholar Bridgit O Crews, Bridgit O Crews Department of Pathology and Laboratory Medicine, University of California Irvine School of Medicine, Orange, CA Address correspondence to this author at: Department of Pathology and Laboratory Medicine, University of California Irvine School of Medicine, 101 The City Dr., Orange, CA 92868. Fax 714-456-2975; e-mail crewsb@hs.uci.edu. Search for other works by this author on: Oxford Academic Google Scholar Jennifer S Woo, Jennifer S Woo Department of Pathology and Laboratory Medicine, University of California Irvine School of Medicine, Orange, CA Search for other works by this author on: Oxford Academic Google Scholar Sherif Rezk, Sherif Rezk Department of Pathology and Laboratory Medicine, University of California Irvine School of Medicine, Orange, CA Search for other works by this author on: Oxford Academic Google Scholar Minh-Ha Tran Minh-Ha Tran Department of Pathology and Laboratory Medicine, University of California Irvine School of Medicine, Orange, CA Search for other works by this author on: Oxford Academic Google Scholar The Journal of Applied Laboratory Medicine, Volume 6, Issue 4, July 2021, Pages 1057–1061, https://doi.org/10.1093/jalm/jfaa159 Published: 24 November 2020 Article history Received: 15 June 2020 Accepted: 17 August 2020 Published: 24 November 2020

BACKGROUND:Racial disparities in SARS-CoV-2 prevalence are apparent. Race is a sociocultural construct, necessitating investigation into how sociocultural factors contribute. METHODS:This cross-sectional study linked laboratory data of adult patients between February 29 and May 15, 2020 with socio-demographics variables from the 2018 American Community Survey (ACS). Medical sites included healthcare organizations in Michigan, New York, North Carolina, California, Florida, Pennsylvania, and Washington. Race was treated as a proxy for racism and not biological essentialism. Laboratory data included patient age, sex, race, ethnicity, test result, test location, and residential ZIP code. ACS data included economic and educational variables contributing to an SES Index, population density, proportion Medicaid, and racial composition for corresponding ZIP code. Associations between race/socioeconomic variables and test results were examined using odds ratios (OR). RESULTS:Of 126 452 patients [mean (SD) age 51.9 (18.4) years; 52 747 (41.7%) men; 68 856 (54.5%) White and 27 805 (22.0%) Black], 18 905 (15.0%) tested positive. Of positive tests, 5238 (SD 27.7%) were White and 7223 (SD 38.2%) were Black. Black race increased the odds of a positive test; this finding was consistent across sites [OR 2.11 (95% CI 1.95-2.29)]. When subset by race, higher SES increased the odds of a positive test for White patients [OR 1.10 (95% CI 1.05-1.16)] but decreased the odds for Black patients [OR 0.92 (95% CI 0.86-0.99)]. Black patients, but not White patients, who tested positive overwhelmingly resided in more densely populated areas. CONCLUSIONS:Black race was associated with SARS-CoV-2 positivity and the relationship between SES and test positivity differed by race, suggesting the impact of socioeconomic status on test positivity is race-specific.