Analytical characterization of the SARS-CoV-2 EURM-017 reference material.

BACKGROUND: Current serological methods for SARS-CoV-2 lack adequate standardization to a universal standard reference material. Standardization will allow comparison of results across various lab-developed and commercial assays and publications. SARS-CoV-2 EURM-017 is human sera reference material containing antibodies directed against SARS-CoV-2 proteins, S1/S2 (full-length spike [S]), S1 receptor-binding domain (S1 RBD), S1, S2, and nucleocapsid (N) protein. The goal of this study was to characterize five antigen-specific serum fractions in EURM-017 for standardization of serology assays. METHODS: Five antigen-specific serum fractions were affinity purified, quantified, and PRNT50 titers compared. Standardization methods were established for two anti-S1 RBD (IgG and Total Ig) and one N protein assay. For the anti-S1 RBD assays, standardization involved determining assay index values for serial dilutions of S1-RBD anti-sera. Index values for the anti-S1 RBD IgG assay and PRNT50 titers were determined for 44 symptomatic COVID-19 patient sera. The index values were converted to EURM-017 ug/mL. RESULTS: Anti-sera protein content was as follows: S1 (17.7 µg/mL), S1 RBD (17.4 µg/mL), S1/S2 (full-length S) (34.1 µg/mL), S2 (29.7 µg/mL), and N protein (72.5 µg/mL). S1 anti-serum had the highest neutralization activity. A standardization method for S1 RBD anti-serum and an anti-S1 RBD IgG assay yielded the linear equation (y = 0.75x-0.10; y = index, x=µg/mL anti-serum). Patient sample index values for the S1-RBD IgG assay correlated well with PRNT50 titers (Pearson r = 0.84). Using the equation above, patient index values were converted to standardized µg/mL. CONCLUSIONS: Standardization of different lab-developed and commercial assays to EURM-017 antigen-specific anti-sera will allow comparison of results across studies globally due to traceability to a single standard reference material.

The 2018 AACC/SYCL PhD Clinical Chemist Compensation Survey.

BACKGROUND: Doctoral level board-certified clinical chemists play an invaluable role in many facets of laboratory medicine and healthcare. However, information concerning their total compensation is sparse. CONTENT: A confidential self-reported compensation survey was conducted by the American Association for Clinical Chemistry's Society for Young Clinical Laboratorians (AACC SYCL) Core Committee from April 1 to April 17, 2018. Respondents provided information on geographic location, employment sector, gender, and years of experience to account for the influence of these variables on compensation. There were 199 respondents in total from the United States and Canada, however, only respondents employed in the United States with an earned doctoral degree and certification by the American Board of Clinical Chemistry (n = 133), were included in the full analysis. In comparison to compensation reported in AACC SYCL salary surveys conducted in 2010 and 2013, early career median salaries are trending upwards after correction for inflation. SUMMARY: This survey is the first to collect the gender of respondents, and identify a pay gap for some geographic groups. However, this gap could be due in part to a difference in the years of experience, since males were highly represented in the group with >20 years of experience (25 out of 35, 71%). Future studies on compensation trends within clinical chemistry that do not rely on self-report are needed to ensure accuracy and completeness of the dataset.

Human chorionic gonadotropin discriminatory zone in ectopic pregnancy: does assay harmonization matter?

OBJECTIVE: To determine the effect that lack of hCG assay harmonization has on the interpretation of a serum hCG concentration with regards to the hCG discriminatory zone. DESIGN: A multisite method comparison study. SETTING: Clinical laboratories. PATIENT(S): Eighty serum samples containing various concentrations of hCG. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Concentrations of hCG obtained from seven hCG reagent platforms. RESULT(S): The hCG concentrations were significantly different across hCG reagent platforms. Seventy-one percent of assay pairs showed significant differences with samples selected based on hCG concentrations between 1,500 and 3,500 IU/L as determined by a comparative method. Relative to the comparative method, the calculated hCG discriminatory zones for five assays were within 9%, and one assay was within 40% of the target concentrations of 1,500 and 3,500 IU/L. CONCLUSION(S): Despite significant differences in hCG concentrations across hCG immunoassays, an hCG concentration within a discriminatory zone of 1,500-3,500 IU/L can be used for all but one commonly used hCG reagent platform.

Relationship between blood alcohol concentration and observable symptoms of intoxication in patients presenting to an emergency department.

AIMS: Clinical and medico-legal decisions often require knowledge of alcohol impairment that is not necessarily revealed by an individual's appearance, and in turn, may not necessarily reflect level of blood alcohol. This study compares clinical signs and symptoms with measured and estimated blood alcohol concentrations (BACs). METHOD: Individuals (n = 384) perceived to be under the influence of alcohol at presentation to an emergency department were assessed by physicians and nurses for clinical features of alcohol intoxication (alcohol symptom checklist, ASC), who were asked to estimate the patient's BAC. Relation to measured BACs was assessed by correlation. RESULTS: BACs ranged from 0 to 418 mg/100 ml. The correlation between the estimated BAC and measured BAC was r = 0.513. Measured BAC correlated with ASC r = 0.250. In subjects without a history of chronic drinking (n = 134) there was a better (P < 0.05) correlation with the ASC score (r = 0.363) versus measured BAC compared with that for chronic drinkers (r = 0.154). The positive predictive value of estimating BAC at or above a particular BAC cut-off decreased from 93.2% at 100 mg/100 ml to 37.7% at 300 mg/100 ml (P < 0.05). CONCLUSIONS: Measured BAC does not correlate well with the outward physical signs of intoxication, especially for chronic drinkers. There is a need for further education on how tolerance masks clinical signs of intoxication for the chronic drinker. BACs should be measured especially in the obtunded where no history (symptoms) can be given by the patient.

Superiority of postmortem liver fentanyl concentrations over peripheral blood influenced by postmortem interval for determination of fentanyl toxicity.

OBJECTIVE: The current study was undertaken to determine the relationship between postmortem (PM) peripheral blood (PB) and liver fentanyl concentrations and the role of measuring liver fentanyl concentrations in cause of death investigations in medical examiner cases in which fentanyl was identified. DESIGN AND METHODS: FB and liver tissue were routinely collected at autopsy from 4 Minnesota medical examiners' offices in 2010-2011. Samples were analyzed by gas chromatography-mass spectrometry (GC-MS). RESULTS: PB fentanyl ranged from <2-15µg/L in non-drug related deaths (n=5), <2-22µg/L from mixed drug toxicity (n=26) and 3.7-56µg/L from fentanyl toxicity (n=33). Liver fentanyl ranged from 11 to 104µg/kg, 6 to 235µg/kg, and 18 to 365µg/kg, respectively. PB and liver fentanyl showed a modest correlation (r=0.67). PM interval to the liver/blood ratio showed a decreasing ratio over increasing PM interval in cases from fentanyl and mixed drug toxicity. Liver fentanyl concentrations best define therapeutic use at <23µg/kg and fatal toxicity at >56µg/kg, without substantial overlap as found in blood fentanyl concentrations. CONCLUSION: Discriminatory liver fentanyl concentrations suggestive of therapeutic or toxic drug levels may better assist cause of death determination in cases of suspected fentanyl toxicity than postmortem PB concentrations. Peripheral blood fentanyl concentrations appear to undergo postmortem redistribution, associated with an increasing PM interval.

Diseased skeletal muscle: a noncardiac source of increased circulating concentrations of cardiac troponin T.

OBJECTIVES: The purpose of this study was to determine whether there is immunoreactive cardiac troponin T (cTnT) expression in diseased skeletal muscle that might cause possible false-positive increases in cTnT. BACKGROUND: Cardiac troponin (I or T) is the biomarker of choice for the diagnosis of cardiac injury. Recently, we were presented with a case that challenged the specificity of cTnT. METHODS: Patients with myopathies seen in the Neuromuscular Clinic at the Mayo Clinic were screened for increases in cTnT. If present, an assay for cTnI was performed. If normal, skeletal biopsy tissue was obtained for Western blot analysis using the capture and detection antibodies from both the fourth-generation and high-sensitivity cTnT assays. Results were compared with findings in normal cardiac tissue. RESULTS: Sixteen patients had increases in cTnT but not cTnI. All had a myopathy by clinical evaluation, clinical testing, and biopsy. Four residual biopsy samples were obtained. All 3 antibodies used in the cTnT (M11.7, M7) and high-sensitivity cTnT (5D8, M7) assays were immunoreactive with a 37- to 39-kDa protein in all 4 diseased skeletal muscle biopsy specimens and in cardiac tissue. A second immunoreactive isoform (34 to 36 kDa) was also found in 1 patient. None of the noncardiac control tissues expressed immunoreactive protein. CONCLUSIONS: These results document that there are forms in diseased skeletal muscle that could cause increases in circulating levels of cTnT. These increases could reflect re-expressed isoforms. Clinicians need to be aware of the possibility that noncardiac increases in cTnT may occur and lead to a possible false-positive diagnosis of cardiac injury when skeletal muscle pathology is present.

Postmortem redistribution of fentanyl in blood.

Fentanyl concentrations were measured in postmortem specimens collected in 20 medical examiner cases from femoral blood (FB), heart blood (HB), heart tissue, liver tissue, and skeletal muscle. Unique was a subset of 7 cases in which FB was obtained at 2 postmortem intervals, shortly after death (FB1) and at autopsy (FB2). The mean collection times of FB1 and FB2 after death were 4.0 and 21.6 hours, respectively. Fentanyl concentrations for FB1 and FB2 ranged from undetectable to 14.6 microg/L (mean, 4.6 microg/L) and 2.0 to 52.5 microg/L (mean, 17.3 microg/L), respectively. Corresponding mean HB, liver tissue, and heart tissue fentanyl concentrations were 29.8 microg/L, 109.7 mg/kg, and 103.4 mg/kg, respectively. The fentanyl HB/FB1 ratio (mean, 8.39) was higher compared with the corresponding HB/FB2 ratio (mean, 3.48). These results suggest that postmortem redistribution of fentanyl can occur in FB.