Performance of Three Anti-SARS-CoV-2 Anti-S and One Anti-N Immunoassays for the Monitoring of Immune Status and Vaccine Response.

This study aimed to evaluate and compare the performance of three anti-S and one anti-N assays that were available to the project in detecting antibody levels after three commonly used SARS-CoV-2 vaccines (Pfizer, Moderna, and Johnson & Johnson). It also aimed to assess the association of age, sex, race, ethnicity, vaccine timing, and vaccine side effects on antibody levels in a cohort of 827 individuals. In September 2021, 698 vaccinated individuals donated blood samples as part of the Association for Diagnostics & Laboratory Medicine (ADLM) COVID-19 Immunity Study. These individuals also participated in a comprehensive survey covering demographic information, vaccination status, and associated side effects. Additionally, 305 age- and gender-matched samples were obtained from the ADLM 2015 sample bank as pre-COVID-19-negative samples. All these samples underwent antibody level analysis using three anti-S assays, namely Beckman Access SARS-CoV-2 IgG (Beckman assay), Ortho Clinical Diagnostics VITROS Anti-SARS-CoV-2 IgG (Ortho assay), Siemens ADVIA Centaur SARS-CoV-2 IgG (Siemens assay), and one anti-N antibody assay: Bio-Rad Platelia SARS-CoV-2 Total Ab assay (BioRad assay). A total of 827 samples (580 COVID-19 samples and 247 pre-COVID-19 samples) received results for all four assays and underwent further analysis. Beckman, Ortho, and Siemens anti-S assays showed an overall sensitivity of 99.5%, 97.6%, and 96.9%, and specificity of 90%, 100%, and 99.6%, respectively. All three assays indicated 100% sensitivity for individuals who received the Moderna vaccine and boosters, and over 99% sensitivity for the Pfizer vaccine. Sensitivities varied from 70.4% (Siemens), 81.5% (Ortho), and 96.3% (Beckman) for individuals who received the Johnson & Johnson vaccine. BioRad anti-N assays demonstrated 46.2% sensitivity and 99.25% specificity based on results from individuals with self-reported infection. The highest median anti-S antibody levels were measured in individuals who received the Moderna vaccine, followed by Pfizer and then Johnson & Johnson vaccines. Higher anti-S antibody levels were significantly associated with younger age and closer proximity to the last vaccine dose but were not associated with gender, race, or ethnicity. Participants with higher anti-S levels experienced significantly more side effects as well as more severe side effects (e.g., muscle pain, chills, fever, and moderate limitations) (p < 0.05). Anti-N antibody levels only indicated a significant correlation with headache. This study indicated performance variations among different anti-S assays, both among themselves and when analyzing individuals with different SARS-CoV-2 vaccines. Caution should be exercised when conducting large-scale studies to ensure that the same platform and/or assays are used for the most effective interpretation of the data.

T Cell Responses Correlate with Self-Reported Disease Severity and Neutralizing Antibody Responses Predict Protection against SARS-CoV-2 Breakthrough Infection.

OBJECTIVES: The objective of this prospective study was to investigate the role of adaptive immunity in response to SARS-CoV-2 vaccines. DESIGN AND METHODS: A cohort of 677 vaccinated individuals participated in a comprehensive survey of their vaccination status and associated side effects, and donated blood to evaluate their adaptive immune responses by neutralizing antibody (NAb) and T cell responses. The cohort then completed a follow-up survey to investigate the occurrence of breakthrough infections. RESULTS: NAb levels were the highest in participants vaccinated with Moderna, followed by Pfizer and Johnson & Johnson. NAb levels decreased with time after vaccination with Pfizer and Johnson & Johnson. T cell responses showed no significant difference among the different vaccines and remained stable up to 10 months after the study period for all vaccine types. In multivariate analyses, NAb responses (<95 U/mL) predicted breakthrough infection, whereas previous infection, the type of vaccine, and T cell responses did not. T cell responses to viral epitopes (<0.120 IU/mL) showed a significant association with the self-reported severity of COVID-19 disease. CONCLUSION: This study provides evidence that NAb responses to SARS-CoV-2 vaccination correlate with protection against infection, whereas the T cell memory responses may contribute to protection against severe disease but not against infection.

Elevated methemoglobin levels in patients treated with hydroxocobalamin: a case series and in-vitro analysis.

BACKGROUND: Historically, the first step in treating cyanide (CN-) toxicity utilized antidotes to induce methemoglobinemia. This is concerning in patients who are already hypoxemic or have elevated carboxyhemoglobin. Hydroxocobalamin (OHCbl) is now the first-line antidote for CN- toxicity and is not known to induce methemoglobinemia. We observed elevated methemoglobin (MetHb) levels in several patients treated with OHCbl and sought to investigate the incidence of MetHb formation following administration of OHCbl. METHODS: Chart review: A single-center, retrospective case series of patients who received 5 or 10 g of hydroxocobalamin from 01/01/2011 through 04/30/2019. Data was analyzed using descriptive statistics. In-vitro study: Discarded blood was separated into whole blood and plasma samples. OHCbl and normal saline was added to reach 0×, 1×, 2×, and 4× peak therapeutic concentrations and analyzed at times 0, 2, and 4 h after administration. RESULTS: Chart review: Twenty-seven cases of OHCbl administration were identified. The median age was 53 years (IQR 38 - 64) and 20 (74.1%) were male. Exposure to a house fire or smoke inhalation was the reason for OHCbl administration in 21 (77.8%) patients. Five (18.5%) patients received 10 g of OHCbl while the rest received 5 g. Six (22.2%) patients developed methemoglobinemia, all after 5 g OHCbl administration; four had been exposed to fire and smoke, two received the medication for severe acidosis of unknown etiology not related to fire or smoke. The median peak level was 7.1% (IQR 2.2 - 16.4%) at a median time of 11.4 h post-administration. Two patients received methylene blue (MB), neither responded. Death occurred in 17 (63%) cases. In-vitro study: We observed a dose dependent elevation in total hemoglobin but did not detect any increase in MetHb. CONCLUSION: We observed a noteworthy temporal association between the formation of methemoglobinemia and the administration of hydroxocobalamin. This does not appear to be an artifact of the CO-oximeters. This could have profound implications for patients who are already hypoxemic or have impaired oxygen carrying capacity from carboxyhemoglobin.

Glucose-independent, black-white differences in hemoglobin A1c levels: a cross-sectional analysis of 2 studies.

BACKGROUND: A previous study of participants with prediabetes found that hemoglobin A(1c) (HbA(1c)) levels differed between black and white participants with no differences in glucose concentration. OBJECTIVE: To determine whether black-white differences in HbA(1c) level are present in other populations and across the full spectrum of glycemia. DESIGN: Cross-sectional, retrospective. SETTING: Outpatient. PARTICIPANTS: 1581 non-Hispanic black and white participants between 18 and 87 years of age without known diabetes in the SIGT (Screening for Impaired Glucose Tolerance) study and 1967 non-Hispanic black and white participants older than 40 years without known diabetes in the NHANES III (Third National Health and Nutrition Examination Survey). MEASUREMENTS: HbA(1c) levels, anthropometry, and plasma glucose levels during oral glucose tolerance testing. RESULTS: Hemoglobin A(1c) levels were higher in black than in white participants with normal glucose tolerance (0.13 percentage point [P < 0.001] in the SIGT sample and 0.21 percentage point [P < 0.001] in the NHANES III sample), prediabetes (0.26 percentage point [P < 0.001] and 0.30 percentage point [P < 0.001], respectively), or diabetes (0.47 percentage point [P < 0.020] and 0.47 percentage point [P < 0.013], respectively) after adjustment for plasma glucose levels and other characteristics known to correlate with HbA(1c) levels. LIMITATION: The mechanism for the differences is unknown. CONCLUSION: Black persons have higher HbA(1c) levels than white persons across the full spectrum of glycemia, and the differences increase as glucose intolerance worsens. These findings could limit the use of HbA(1c) to screen for glucose intolerance, indicate the risk for complications, measure quality of care, and evaluate disparities in health.

Does Lidocaine Cause False Positive Results on Cocaine Urine Drug Screen?

BACKGROUND: Individuals who have tested positive for cocaine have claimed that lidocaine, or its primary metabolite, norlidocaine (monoethylglycinexylidide (MEGX)), have caused false positive results for the cocaine metabolite benzoylecgonine (BE) on urinary immunoassay testing. OBJECTIVE: The goal of the study was to determine if lidocaine exposure from routine medical procedures can result in false positives on a commercially available cocaine immunoassay urine drug screen (UDS). METHODS: We performed a cross-sectional observational study of patients receiving lidocaine as part of their regular care. Standard immunoassay drug screens and confirmatory liquid chromatography-mass spectrometry (LC-MS) were performed on all urine samples to assess for MEGX and BE. RESULTS: In total, 168 subjects were enrolled; 121 samples positive for lidocaine were ultimately included for analysis. One hundred fourteen of the 121 were also positive for MEGX. None of the 121 were positive for cocaine/BE on the UDS (95% CI), 0-3.7% for the full sample and 0-3.9% for the 114 who tested positive for MEGX. CONCLUSION: The present study found no evidence that lidocaine or norlidocaine are capable of producing false positive results on standard cocaine urine immunoassays.

Random plasma glucose in serendipitous screening for glucose intolerance: screening for impaired glucose tolerance study 2.

BACKGROUND: With positive results from diabetes prevention studies, there is interest in convenient ways to incorporate screening for glucose intolerance into routine care and to limit the need for fasting diagnostic tests. OBJECTIVE: The aim of this study is to determine whether random plasma glucose (RPG) could be used to screen for glucose intolerance. DESIGN: This is a cross-sectional study. PARTICIPANTS: The participants of this study include a voluntary sample of 990 adults not known to have diabetes. MEASUREMENTS: RPG was measured, and each subject had a 75-g oral glucose tolerance test several weeks later. Glucose intolerance targets included diabetes, impaired glucose tolerance (IGT), and impaired fasting glucose(110) (IFG(110); fasting glucose, 110-125 mg/dl, and 2 h glucose < 140 mg/dl). Screening performance was measured by area under receiver operating characteristic curves (AROC). RESULTS: Mean age was 48 years, and body mass index (BMI) was 30.4 kg/m(2); 66% were women, and 52% were black; 5.1% had previously unrecognized diabetes, and 24.0% had any "high-risk" glucose intolerance (diabetes or IGT or IFG(110)). The AROC was 0.80 (95% CI 0.74-0.86) for RPG to identify diabetes and 0.72 (0.68-0.75) to identify any glucose intolerance, both highly significant (p < 0.001). Screening performance was generally consistent at different times of the day, regardless of meal status, and across a range of risk factors such as age, BMI, high density lipoprotein cholesterol, triglycerides, and blood pressure. CONCLUSIONS: RPG values should be considered by health care providers to be an opportunistic initial screening test and used to prompt further evaluation of patients at risk of glucose intolerance. Such "serendipitous screening" could help to identify unrecognized diabetes and prediabetes.

Is a 500-Cell Count Necessary for Bone Marrow Differentials?: A Proposed Analytical Method for Validating a Lower Cutoff.

OBJECTIVES: By convention, 500 cells are counted for bone marrow aspirate differentials. Evidence supporting such a cutoff is lacking. We hypothesized that 300-cell counts could be sufficient. METHODS: Cell count results from 165 cases, for which values were recorded at 300 and 500 cells, were analyzed. We tested for statistical differences and changes in diagnostic classification between the two cutoffs. RESULTS: Three hundred cell counts did not produce diagnostically different results, particularly for myeloblasts and plasma cells, where cell percentages are critical for disease classification. Method comparison analysis did not reach statistical significance for any cell type when comparing the two methods. Bias plots showed narrow, even spread about the mean bias. Contingency table analysis yielded no significant diagnostic discrepancies. CONCLUSIONS: Performing differential counts on 300 cells would produce clinically and statistically similar results to 500 cells. Reducing the cell number counted has potential cost/labor reductions without affecting quality of care.

Albumin adsorption onto surfaces of urine collection and analysis containers.

BACKGROUND: Adsorption of albumin onto urine collection and analysis containers may cause falsely low concentrations. METHODS: We added (125)I-labeled human serum albumin to urine and to phosphate buffered solutions, incubated them with 22 plastic container materials and measured adsorption by liquid scintillation counting. RESULTS: Adsorption of urine albumin (UA) at 5-6 mg/l was <0.9%; and at 90 mg/l was <0.4%. Adsorption was generally less at pH8 than pH5 but only 3 cases had p<0.05. Adsorption from 11 unaltered urine samples with albumin 5-333 mg/l was <0.8%. Albumin adsorption for the material with greatest binding was extrapolated to the surface areas of 100 ml and 2l collection containers, and to instrument sample cups and showed <1% change in concentration at 5 mg/l and <0.5% change at 20 mg/l or higher concentrations. Adsorption of albumin from phosphate buffered solutions (2-28%) was larger than that from urine. CONCLUSIONS: Albumin adsorption differed among urine samples and plastic materials, but the total influence of adsorption was <1% for all materials and urine samples tested. Adsorption of albumin from phosphate buffered solutions was larger than that from urine and could be a limitation for preparations used as calibrators.

Teaching laboratory medicine to medical students: implementation and evaluation.

CONTEXT: Laboratory medicine is an integral component of patient care. Approximately 60% to 70% of medical decisions are based on laboratory results. Physicians in specialties that order the tests are teaching medical students laboratory medicine and test use with minimal input from laboratory scientists who implement and maintain the quality control for those tests. OBJECTIVE: To develop, implement, and evaluate a 1.5-day medical student clinical laboratory experience for fourth-year medical students in their last month of training. DESIGN: The experience was devised and directed by laboratory scientists and included a panel discussion, laboratory tours, case studies that focused on the goals and objectives recently published by the Academy of Clinical Laboratory Physicians and Scientists, and medical-student presentations highlighting salient points of the experience. The same knowledge quiz was administered at the beginning and end of the experience and 84 students took both quizzes. RESULTS: A score of 7 or more was obtained by 16 students (19%) on the initial quiz, whereas 34 (40%) obtained the same score on the final quiz; the improvement was found to be statistically significant (P  =  .002; t  =  3.215), particularly in 3 out of the 10 questions administered. CONCLUSIONS: Although the assessment can only measure a small amount of knowledge recently acquired, the improvement observed by fourth-year medical students devoting a short period to learning laboratory medicine principles was encouraging. This medical student clinical laboratory experience format allowed teaching of a select group of laboratory medicine principles in 1.5 days to an entire medical school class.

Acute chloroform ingestion successfully treated with intravenously administered N-acetylcysteine.

Chloroform, a halogenated hydrocarbon, causes central nervous system depression, cardiac arrhythmias, and hepatotoxicity. We describe a case of chloroform ingestion with a confirmatory serum level and resultant hepatotoxicity successfully treated with intravenously administered N-acetylcysteine (NAC). A 19-year-old man attempting suicide ingested approximately 75 mL of chloroform. He was unresponsive and intubated upon arrival. Intravenously administered NAC was started after initial stabilization was complete. His vital signs were normal. Admission laboratory values revealed normal serum electrolytes, AST, ALT, PT, BUN, creatinine, and bilirubin. Serum ethanol level was 15 mg/dL, and aspirin and acetaminophen were undetectable. The patient was extubated but developed liver function abnormalities with a peak AST of 224 IU/L, ALT of 583 IU/L, and bilirubin level reaching 16.3 mg/dL. NAC was continued through hospital day 6. Serum chloroform level obtained on admission was 91 µg/mL. The patient was discharged to psychiatry without known sequelae and normal liver function tests. The average serum chloroform level in fatal cases of inhalational chloroform poisoning was 64 µg/mL, significantly lower than our patient. The toxicity is believed to be similar in both inhalation and ingestion routes of exposure, with mortality predominantly resulting from anoxia secondary to central nervous system depression. Hepatocellular toxicity is thought to result from free radical-induced oxidative damage. Previous reports describe survival after treatment with orally administered NAC, we report the first use of intravenously administered NAC for chloroform ingestion. Acute oral ingestion of chloroform is extremely rare. Our case illustrates that with appropriate supportive care, patients can recover from chloroform ingestion, and intravenously administered NAC may be of benefit in such cases.

Age, BMI, and race are less important than random plasma glucose in identifying risk of glucose intolerance: the Screening for Impaired Glucose Tolerance Study (SIGT 5).

OBJECTIVE: Age, BMI, and race/ethnicity are used in National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and American Diabetes Association (ADA) guidelines to prompt screening for pre-diabetes and diabetes, but cutoffs have not been evaluated rigorously. RESEARCH DESIGN AND METHODS: Random plasma glucose (RPG) was measured and 75-g oral glucose tolerance tests were performed in 1,139 individuals without known diabetes. Screening performance was assessed by logistic regression and area under the receiver operating characteristic curve (AROC). RESULTS: NIDDK/ADA indicators age >45 years and BMI >25 kg/m(2) provided significant detection of both diabetes and dysglycemia (both AROCs 0.63), but screening was better with continuous-variable models of age, BMI, and race and better still with models of age, BMI, race, sex, and family history (AROC 0.78 and 0.72). However, screening was even better with RPG alone (AROCs 0.81 and 0.72). RPG >125 mg/dl could be used to prompt further evaluation with an OGTT. CONCLUSIONS: Use of age, BMI, and race/ethnicity in guidelines for screening to detect diabetes and pre-diabetes may be less important than evaluation of RPG. RPG should be investigated further as a convenient, inexpensive screen with good predictive utility.

The "metabolic syndrome" is less useful than random plasma glucose to screen for glucose intolerance.

AIMS: To compare the utility of metabolic syndrome (MetS) to random plasma glucose (RPG) in identifying people with diabetes or prediabetes. METHODS: RPG was measured and an OGTT was performed in 1155 adults. Test performance was measured by area under the receiver-operating-characteristic curve (AROC). RESULTS: Diabetes was found in 5.1% and prediabetes in 20.0%. AROC for MetS with fasting plasma glucose (FPG) was 0.80 to detect diabetes, and 0.76 for diabetes or prediabetes--similar to RPG alone (0.82 and 0.72). However, the AROC for MetS excluding fasting plasma glucose was lower: 0.69 for diabetes (p<0.01 vs. both RPG and MetS with FPG), and 0.69 for diabetes or prediabetes. AROCs for MetS with FPG and RPG were comparable and higher for recognizing diabetes in blacks vs. whites, and females vs. males. MetS with FPG was superior to RPG for identifying diabetes only in subjects with age <40 or BMI <25. CONCLUSIONS: MetS features can be used to identify risk of diabetes, but predictive usefulness is driven largely by FPG. Overall, to identify diabetes or prediabetes in blacks and whites with varying age and BMI, MetS is no better than RPG--a more convenient and less expensive test.