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Abstract Background Alternative assessment of performance (AAP) for specific immunological analytes is challenging due to biological and analytical variability. The main objective of this study was to evaluate performance of the laboratory AAP program for effectiveness and gaps. Methods A historical analysis of AAP for fifteen (n=14) specific immunology biomarkers from 2017 – 2021, averaging 64 challenges per year, was performed. The acceptance criteria defined for each analyte were based on the AAP result percentage difference from the target. Testing was categorized by methodology: enzyme-linked immunosorbent assay (ELISA), electrochemiluminescent immunoassay (ECL), fluoroenzyme immunoassay (FEIA) and multiplex immunoassay (MIA). The performance of each analyte was evaluated against established acceptance criteria; AAP failures were categorized based on the failed parameter. A review of each analyte’s inter-precision data was completed to demonstrate the performance of each analyte during initial validation. Following this evaluation, modified acceptance criteria were established, and an assessment of analyte performance for AAP was completed to determine impact. Results Current percent difference acceptability for testing ranged from 20% to 25% of target. AAP success rate was 99%. Major AAP failure categories were identified as AAP material, methodological, AAP evaluation, technical, analytical, or non-identifiable explanation after extensive troubleshooting. Review of each analyte’s inter-precision data varied between 2% to 22%. Following the evaluation, modifications were made to expand the percent difference acceptability from 20% to 30% of target for each analyte depending on their analytical performance. AAP success rate post modification was 98%. Conclusion Analysis of AAP performance pre and post AAP acceptance criteria modification showed no significant increase in AAP failures. Success rate remains stable. Modifications to acceptance criteria were made based on clinical impact of testing and to align with known analytical performance. Expanded acceptance criteria improved flexibility in reviewing of AAP acceptance and allowed for a comprehensive analysis of overall analyte performance.

Abstract Background Nuclear magnetic resonance (NMR)–based lipoprotein analysis enables simultaneous quantification of lipoprotein particle concentration and size. Although primarily applied to cardiovascular disease (CVD) management, characteristic lipoprotein changes are also reported in patients with diabetes and chronic kidney disease (CKD). Both diseases are associated with increases in small low-density lipoprotein (sLDL), large very-low density lipoprotein (LVLDL), and decreased large high-density lipoprotein (LHDL). To elucidate this issue further, we aimed to evaluate NMR-measured lipoprotein size and particle concentrations in patients undergoing clinically ordered measured Iothalamate glomerular filtration rate (GFR) assessment, stratified by kidney function and diabetes status. Methods Lipoproteins were measured using Axinon software (numares AG, Regensburg, Germany) on a 600MHz Bruker NMR in residual clinical sera from patients undergoing iothalamate renal clearance (n=330). Reduced kidney function was defined as a measured GFR <60 mL/min/1.73m2. A lipoprotein insulin resistance (LPIR) score was calculated using LVLDL, sLDL, and LHDL particle concentrations and size using published methods (Otvos, et. al). Associations between lipoproteins and disease status were assessed using Wilcoxon rank-sum or Pearson’s chi-squared tests, as appropriate. Results Of 330 participants, 159 (48%) had reduced eGFR. No statistically significant differences in lipoprotein parameters were observed by kidney function. Participants with reduced GFR showed non-significant trends toward increased LVLDL, [median (IQR): 1.6(1.0-3.8) vs. 1.5(0.9-2.7) nmol/L; p =0.3], and decreased LHDL [3.4(1.1-7.2) vs. 4.3(1.7-6.4) mcmol/L; p=0.4]. No differences between patients with reduced GFR were observed for sLDL [436(280-604) vs. 455(286-631) nmol/L; p=0.5] or LPIR score [46(33-64) vs. 46(34-60; p=0.5]. Diabetes was diagnosed in 86 (26%) participants. Compared to non-diabetic participants, those with diabetes had significantly increased LVLDL [2.15(1.00-4.50) vs. 1.50(0.90-2.80) nmol/L; p=0.01], decreased LHDL [3.0(1.1-5.3) vs. 4.3(1.9-7.0) mcmol/L; p=0.04], and smaller LDL size [20.9(20.6-21.1) vs. 21.1(20.8-21.3) nm; p<0.001]. Despite increased sLDL in diabetes [462(324-655) vs. 443(273-612) nmol/L], the difference was not significant (p=0.3). The LPIR score was significantly higher among participants with diabetes [53(37-68) vs. 45(32-60); p<0.01]. Conclusion Our data support prior reports that diabetes is associated with adverse changes in lipoprotein particle size and concentration. In contrast, measured kidney function showed no significant independent association with NMR lipoprotein parameters in this cohort, nor does it skew diabetic evaluations. Our data suggests that the association between kidney function and lipoprotein patterns is not robust and may in part be caused due to diabetic related changes. Irrespective of eGFR, LPIR was a predictor of incident diabetes.

Abstract Background LabOps is an internally developed workflow tracking system at Mayo Clinic that records time-stamped specimen handoffs and process steps from extraction through real-time PCR result reporting. Implemented in 2021, LabOps was designed to improve workflow efficiency and reduce turnaround time (TAT) by enabling shared use of patient nucleic acid eluates across multiple targeted, laboratory-developed test (LDT), PCR assays. The objective of this study was to evaluate PCR workflows using LabOps analytics to identify process inefficiencies and implement targeted operational improvements to reduce TAT without increasing staffing. Methods From March 1, 2023, to November 20, 2024, time-stamped workflow data were extracted from LabOps for 40 LDT PCR assays comprising 11,250 individual PCR assay batches ranging from 1 to 94 individual patient samples each. Tracked workflow steps included specimen receipt, pre-extraction setup, extraction completion, PCR batch assembly (up to 94 reactions plus controls per plate), run completion on the Roche LC480 instrument, data analysis, and result report verification. Average time to completion for each step was calculated across assays and specimen types. Line graphs were generated to visualize step-specific TAT trends. Based on workflow analysis, targeted operational interventions—including modification of test run cadence—were implemented. TAT was compared before and after intervention. Results Pre-intervention total TAT averaged 41 hours (range: 29–78 hours) from specimen receipt to result release. Two primary contributors to delay were identified: (1) tissue processing and (2) PCR batch assembly cadence. Tissue processing required an average of 24 hours (range: 15–29 hours), significantly increasing TAT for assays accepting tissue specimens. Approximately 90% of assays were assembled once daily despite available capacity for additional reactions per run. An intervention was implemented for 29 PCR assays (excluding those requiring specialized extraction or amplification protocols) to increase run cadence to twice daily at 12-hour intervals. This change reduced the average batch assembly step TAT from 17 hours (with a range of 16-18 hours) to 9 hours (with a range of 8–10 hours), representing approximately a 50% reduction. Figure 1 demonstrates the reduction in TAT for the Epstein Barr Virus (EBV) PCR test pre- and post-implementation of the cadence change. The modified cadence also distributed workload more evenly between day and evening shifts. Conclusion Data-driven workflow optimization using LabOps analytics enabled a substantial reduction in PCR turnaround time without additional staffing. Increasing run cadence to twice daily reduced batch assembly TAT by approximately 50%. Implementation of an automated, continuous TAT monitoring system provides a scalable framework to proactively adjust workflows in response to increased testing demand, seasonal surges, or future outbreak scenarios.

Abstract Background Viscoelastic Testing (VET) can provide information about the status of coagulation factors, platelet count, platelet function, and fibrinolysis in fresh whole blood and is used in various critical care settings. Our current VET method, Haemonetics TEG 5000 (5000) (Boston, MA) is being discontinued in the next few years. As potential replacements, we evaluated 3 cartridge-based VET analyzers: Werfen ROTEM Sigma Thromboelastometry System (Sigma) (Bedford, MA), Haemonetics TEG 6S Hemostasis System (6S), and Hemosonics Quantra Hemostasis Analyzer (Quantra) (Durham, NC). These cartridge-based VET analyzers can be used at the point of care or in the laboratory. For our evaluation, we focused on 1 cartridge type per method: ROTEM sigma complete + hep on Sigma, Global Hemostasis-HN on 6S, and QPlus on Quantra. Methods We collected fresh Na Citrate tubes (N=69) from laboratory volunteers. Working in sets of 3, tubes were analyzed native and spiked with drugs (heparin, Eptifibatide, Argatroban, Bivalirudin, tPA) intended to affect clot initiation. We calculated the percentage of clot initiation times (R parameter on 6S, CT parameter on Sigma and Quantra) outside each platform’s reportable range. We timed a subset of samples to determine average time to clot initiation and clot strength (A20 parameter on Sigma, MA on 6S and CS by Quantra). In addition to freshly collected samples, we analyzed residual clinical Na Citrate tubes (N=25) from operating room patients. We compared error rates between the 3 methods. A small group of laboratory staff provided user feedback on each analyzer. Results Percentage of results outside reportable clot initiation range/max times (6, 17, and 8 minutes for Sigma CT, 6S R, and Quantra CT) was 23% (16/69) on Sigma, 38% (26/69) on 6S and 13% (9/69) on Quantra. Average time to first result and clot strength for Sigma (N=11) was 9.1 and 21.7 minutes, 6S 8.9 and 29.1 minutes, and Quantra 6.5 and 11.3 minutes. Overall error rates were 3% (3/101) for both 6S and Sigma and 8% (8/104) for Quantra. On Sigma, the 3 errors indicated partial sample aspiration; recollection would be required. The errors on 6s occurred while inserting the cartridge and required a system reboot to resolve. On Quantra, all 8 samples with errors gave partial results but would have required recollection to obtain complete results. Laboratory staff appreciated the ease of sample loading on Sigma and Quantra, though were concerned that loading the whole 2.7 mL Na Citrate tube could lead to an increase in redraws for errors or sample issues. Sample loading by pipette on 6S may increase the potential for exposures, but staff liked that the smaller sample volume required for the 6S would allow use of the smaller volume 1.8 mL Na Citrate tube. They found the speed to results on the Quantra to be a potential advantage. Conclusion Analytical performance of all 3 platforms was relatively similar and could provide the needed coagulation measures to clinical providers. Time to clot initiation and clot strength, reportable range, error rates and user feedback are important considerations when choosing a VET platform.

Abstract Background Our institution has a cTnT biomarker panel consisting of an initial cTnT, followed by a 2-hour and if necessary, a 6-hour collection. Accurate cTnT results are important for rapid diagnosis of acute coronary syndrome and to avoid prolonged stays in an emergency room. We compared cTnT results from Roche (Roche, Indianapolis, IN) cobas e 801 (801), e 601 (601), and two e 402 (402) instruments. Methods Comparisons (N=91) were completed using cTnT results from a single 601 instrument as the reference and comparing to the results from two 402 analyzers. Additional comparisons (N=45) were completed using cTnT results from an 801 as reference compared to results from the 402 instruments. Residual plasma separator tubes (PST) from clinically ordered cTnT testing were used. To ensure sample quality all plasma samples were aliquoted and recentrifuged before testing on each analyzer. Analysis was completed on all analyzers within 1 hour of the first comparison measurement. Acceptance limits were set as Passing-Bablok slope 1.00 ±0.10 and bias ±5 ng/L (for cTnT values <100 ng/L) or ±5% (for cTnT values =100 ng/L) when compared to reference 601 or 801. Student’s T-Test was performed to assess statistical significance between the observed mean bias between Pure instruments compared to the reference instrument, significance was defined as p =0.05. Results When compared to 601, results from the first 402 instrument demonstrated a slope of 1.11 with 54% (49/91) of samples within our acceptance criteria and a mean difference of 115 ng/L (Figure 1). Results from the second 402 instrument had a slope of 1.11 with 53% (48/91) within acceptance limits with a mean difference of 121 ng/L (p = 0.53, no difference between 402 instruments). For samples with cTnT <100 ng/L, 88% (36/41) and 88% (36/41) were within acceptance. In cTnT samples =100 ng/L, the mean percent bias was observed as 12% on both 402 analyzers. When using results from the 801 instrument as reference, results from the first 402 instrument had a slope of 0.954 with 77% (33/43) within acceptable limits and a mean difference of -61 ng/L. Results from the second 402 instrument had a slope of 0.978 with 79% (34/43) within acceptable limits and a mean difference of -39 ng/L (p = 0.33, no difference between 402 instruments). In samples with cTnT <100, comparisons to the 801 showed 82% (14/17) and 94% (16/17) within acceptance criteria and a mean difference of 2 ng/L on each 402 instrument. For cTnT samples with concentrations =100 ng/L, the mean percent bias was -2% on both 402 instruments. Conclusion We observed proportional bias on the 402 instruments compared to both 601 and 801 instruments, with large and clinically significant differences particularly when comparing to the 601 at higher cTnT concentrations. To avoid a delta being caused by observed systematic bias we will complete all cTnT testing within a panel on one platform.

Abstract Background Quantitative M-protein Study, Serum (QMPSS), a laboratory developed test, is used to identify and quantify monoclonal immunoglobulins by MALDI-TOF MS MASS-FIX. Monoclonal IgM proteins with glycosylated light chains (LC) are rare (5% of total M-proteins identified). In a given month approximately 3 cases of the 71 reported IgM monoclonal proteins with glycosylated light chains present with indeterminate kappa or lambda LC. The structure of the intact IgM monoclonal protein may restrict access to the Ig-LC constant region resulting in inefficient isolation. The laboratory uses immunofixation electrophoresis (IFE, Sebia) to confirm the Ig-LC isotype in this scenario. This study evaluates a reduction step prior to LC isolation to enhance the detection of the IgM isotype. Methods For QMPSS analysis, serum is added to five immunoaffinity matrices that target IgG, IgA, IgM, Ig-K, and Ig-L (CaptureSelect). After a binding phase, the serum/bead mixtures are washed to remove unbound protein. Finally, Igs are eluted, and the disulfide bonds are reduced, resulting in purified Ig-components. This step is followed by MALDI-TOF MS (Bruker) analysis. M-protein isotypes are determined by pairing each monoclonal protein’s unique LC mass detected in both heavy chain and LC Ig isolates. Twenty de-identified, residual waste serum samples with IgM-M-proteins without clear LC isotype were collected over several months. The proof-of-concept method modification studied to decrease reliance on IFE included use of 2.5 mcL of 0.5M dithiothreitol (DTT) added to kappa and lambda affinity matrix beads prior to sample addition followed by the QMPSS pre-analytical processing. Results For the 20 IgM glycosylated M-proteins, M-spike concentrations ranged from 0.026 to 0.506 g/dL. Using QMPSS and IFE lab routine protocol, the IgM samples were reported as glyco MK (n=17), biclonal MK+ML (n=1), and 2 samples were reported as negative. 16 of the 20 samples used in the study had IgM kappa monoclonal proteins that were identifiable on IFE. 13 of these IgM kappa monoclonal proteins were also identifiable by QMPSS-DTT. Additionally, 1 IgM kappa monoclonal protein was identifiable on QMPSS-DTT but was reported as equivocal on IFE. Of the 6 samples that the DTT method could not resolve, IFE was positive for 3. As shown by the 3 samples in which the light chain was identified only by IFE, the need for IFE as a confirmatory assay is not fully eliminated. The 3 false negative samples had M-quant values of 0.036g/dL, 0.043g/dL, and 0.117g/dL. More extensive testing would be required to determine the cause and prevalence of the observed discrepancy between IFE and QMPSS-DTT. Conclusion The use of the alternative QMPSS-DTT method shows potential to improve the capabilities of the QMPSS assay to identifying IgM monoclonal proteins with glycosylated light chains and would effectively remove the need for IFE in 70% of cases, improving test turnaround time. Further experimentation and optimization could decrease the number of discrepancies.

Abstract Background Albumin measurement in pericardial fluid is frequently requested in our reference laboratory practice. The serum to ascites albumin gradient (SAAG) is used to distinguish between transudative and exudative effusions. However, growing evidence suggests pericardial albumin is less useful in this scenario. Our objective was to validate analytical accuracy of albumin measurement in pericardial fluid and compare frequency of transudate classifications. Methods Albumin concentrations were measured using a Roche Cobas c501, (Roche, Indianapolis, IN). Within-laboratory coefficient of variation (CVWL) and repeatability (CVr) were determined by repeated measurement of pooled clinical residual pericardial fluid. Linearity was assessed by mixing pericardial fluid pools with high and low albumin concentrations. Dilutional recovery from clinically ordered pericardial fluid albumin analyses (n=772) were used to determine analytical accuracy. SAAG transudate diagnostic threshold of 1.1 g/dL (peritoneal) or 1.2 g/dL (pleural) was evaluated in clinical data from patients with paired serum and body fluid albumin measured within a 2-day interval (n=3,031). Results Albumin imprecision in pericardial fluid was assessed at 1.4 g/dL (CVWL = 6.3%, CVr = 5.7%) and 3.1 g/dL (CVWL = 2.2%, CVr = 2.2%). Mixing studies confirmed linearity between 0.5-5.6 g/dL (slope 1.02, R2 = 0.999). Dilutional recovery was performed in 772 clinical orders spanning 0.9 g/dL to 4.8 g/dL, the Passing-Bablok fit of expected versus measured values had slope = 1.09 g/dL and intercept = -0.2 g/dL. In the clinical data, serum albumin was similar for patients in all cases. Pericardial albumin [median(IQR) 2.2(1.0-2.6) g/dL] was significantly higher compared to peritoneal [1.0(0.5-1.7) g/dL; p<0.001] or pleural fluid [1.6(1.0-2.2) g/dL; p<0.001], leading to significantly lower SAAG calculation for pericardial [1.3(0.5-1.9) g/dL] versus peritoneal [1.9(1.4 – 2.4); p<0.001] or pleural fluid [1.5(1.0-2.1); p<0.001]. Applying the SAAG threshold of 1.2 g/dL classified 84% of peritoneal fluids and 58% of pericardial fluids as transudative effusions. The Light’s criteria threshold of 1.2 g/dL led to 65% of pleural fluids and 55% of pericardial fluids being classified as transudative. Conclusion These data show that albumin can be precisely measured in pericardial fluid within a linear range of 0.5-5.6 g/dL. In clinical cases of evaluating SAAG ratio in body fluid samples, albumin concentrations are generally higher in pericardial fluid compared to peritoneal or pleural fluids. This increased pericardial albumin concentration leads to lower SAAG calculations. Application of typical transudate versus exudate thresholds in pericardial fluids leads to more exudative determinations. This data suggests that pericardial fluid may warrant a unique diagnostic threshold to be determined in further studies.

Abstract Background Blood gas (BG) analyzers are essential point-of-care and central laboratory instruments used to assess acid–base status, ventilation, oxygenation, and electrolyte balance in critically ill patients. Cartridge-based systems are increasingly utilized due to simplified maintenance, integrated quality control, and rapid turnaround times. However, inter-instrument variability and method-specific bias remain important considerations, particularly when transitioning between platforms or comparing results with core laboratory analyzers. We evaluated two cartridge-based analyzers—Werfen GEM Premier 7000 (GEM 7000; Bedford, MA) and Siemens RAPIDPoint 500e (RAPIDPoint 500e; Malvern, PA)—compared with our current Radiometer ABL90 FLEX PLUS (ABL90; Brea, CA). Additionally, preanalytical factors—especially hemolysis—can significantly affect potassium and ionized calcium (iCa). Unlike central chemistry analyzers, most BG systems do not assess hemolysis in whole blood. GEM 7000 uniquely incorporates onboard semi-quantitative hemolysis detection. Methods Residual lithium-heparin whole blood syringes (N=120–130) were analyzed on all three platforms within 15 minutes. For analytes with established laboratory methods, paired specimens (N=31–33) were tested on Sysmex XN-1000 (hemoglobin [Hb]; whole blood) and Roche Cobas c501 (sodium [Na], potassium [K], glucose [Glu]; plasma). Acceptability was defined using CLIA Total Allowable Error (TEa) or internally established criteria where CLIA limits were unavailable. Hemolysis index (HI) comparisons (N=76) were performed between GEM 7000 (whole blood) and c501 (plasma following centrifugation). Selected samples were spiked with hemolysate to broaden the analytical range. Agreement was assessed using regression and categorical concordance. Results Compared with ABL90, GEM 7000 demonstrated =90% agreement within CLIA or internal TEa for pH, partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), Hb, fractional carboxyhemoglobin (FCO2Hb), fractional methemoglobin (FMetHb), iCa, and Glu, but lower agreement for fractional oxyhemoglobin (FO2Hb), Na, K, and Lac. RAPIDPoint 500e achieved =90% agreement for pH, pO2, FMetHb, but showed reduced agreement for pCO2, FO2Hb, FCO2Hb, and Lac. (Table 1) Against primary laboratory methods, clinically relevant variability was observed. For Hb, percent within acceptance was 12.5% (ABL90), 62.5% (GEM 7000), and 28.1% (RAPIDPoint 500e). For Na, agreement was highest for ABL90 (96.8%) and lowest for GEM 7000 (64.5%). For K, GEM 7000 demonstrated strongest agreement (86.1%), whereas ABL90 showed the lowest (36.1%). HI correlation between GEM 7000 and c501 was strong (slope 1.005; mean difference 2), with 93.3% of samples within acceptance limits and 96.0% categorical agreement. Conclusion Both candidate analyzers demonstrated acceptable performance for core BG parameters; however, meaningful inter-platform variability was observed for co-oximetry, and Lac. These findings indicate that BG and core laboratory results are not universally interchangeable, and platform-specific bias may influence clinical interpretation, particularly for Hb and K. Institutions transitioning analyzers should consider method validation, clinician education, and potential adjustment of reference or critical value thresholds. The GEM 7000’s integrated hemolysis detection showed strong agreement with a laboratory-based plasma method, supporting its utility for identifying preanalytical interference at the point of testing. Real-time hemolysis assessment may reduce reporting of spurious results, limit unnecessary redraws, and enhance patient safety.

Abstract Background Health disparities affecting Black/African American communities remain a persistent public health challenge, particularly for chronic conditions such as diabetes, cardiovascular disease, and kidney disease. The Love Wins + Health initiative represents a collaborative, community-engaged strategy to reduce these disparities through point-of-care testing (POCT), health education, and culturally responsive outreach. This program was a partnership between Mayo Clinic’s Department of Laboratory Medicine and Pathology (DLMP), Mayo Clinic Community Internal Medicine, and the Rochester, MN Branch of NAACP. It was implemented during the 2025 Juneteenth celebration, an event serving more than 1,000 community members. Phlebotomists played a central role in delivering accessible diagnostic services in a trusted community setting. Volunteer phlebotomists from Mayo Clinic Laboratory Services provided specimen collection and testing support as the primary point of patient interaction. Beyond technical expertise, they functioned as ambassadors of patient-centered care, reinforcing respect, dignity, and cultural sensitivity during testing encounters. This role was essential to establishing trust and ensuring specimen integrity and accurate results. Methods Free testing was promoted through community posters, and an informational health-focused townhall was coordinated with the Rochester, MN Branch of NAACP. The testing event was held June 14, 2025, at Martin Luther King Jr. Park in Rochester, MN. Participants registered on-site and completed an intake form capturing demographics and health history. Three trained phlebotomists performed venipuncture whole blood collections in Mayo Clinic’s Mobile Health vehicle. CLIA-waived POCT was conducted by trained laboratory technologists using Afinion hemoglobin A1c (HbA1c), Cholestech LDX lipid profile, and i-STAT creatinine platforms (Abbott Laboratories). On-site physicians reviewed results and discussed follow-up recommendations. A post-collection survey assessed participant impact. Percentages of abnormal results were calculated, and survey responses were tabulated. The Mayo Clinic Institutional Review Board determined the initiative met criteria for quality improvement and did not require formal review. Results Fifty-one individuals participated (median age 42 years; range 18–81). Participants were 62% female, 36% male, and 2% nonbinary; 27.5% identified as Black/African American. Testing revealed a high prevalence of cardiometabolic abnormalities. Elevated low-density lipoprotein cholesterol was observed in 57.1% of participants, elevated non–high-density lipoprotein cholesterol in 52.0%, and elevated triglycerides in 31.4%. Markers of renal dysfunction, including elevated creatinine and reduced estimated glomerular filtration rate (eGFR), were present in 17.6%. Elevated HbA1c was identified in 13.7% and elevated glucose in 7.8%. Black participants demonstrated higher rates of abnormal HbA1c (20.0% vs 12.1%) and reduced eGFR (20.0% vs 18.2%) compared with non-Black participants. Post-event surveys indicated strong engagement: 84.3% reported improved understanding of their health, 92.2% would recommend screening to others, and 56.9% planned follow-up care. Conclusion The Love Wins + Health initiative demonstrates the value of community-based POCT in identifying undiagnosed cardiometabolic and renal risk factors. The high prevalence of abnormal findings underscores persistent diagnostic care gaps and the need for accessible screening. Immediate result review and on-site clinical consultation supported timely education and referral. This collaborative, community-centered model offers a scalable approach to expanding preventive care access and advancing health equity among populations disproportionately affected by chronic disease.

Abstract Background Comprehensive lipoprotein analysis and interpretation is a cornerstone of cardiovascular disease (CVD) prevention. Often, multiple platforms and assays are used to quantify lipoprotein parameters and apolipoproteins. Growing economic pressure in healthcare systems is driving the need for efficient technologies capable of measuring multiple analytes in a single analytical step. Nuclear magnetic resonance (NMR) enables simultaneous quantification of lipoprotein subclasses and related biomarkers in one integrated measurement. Although apolipoprotein B (ApoB) has previously been described as an NMR-derived parameter, its implementation has been limited to research-use-only (RUO) applications, restricting routine clinical adoption. Herein, we present the IVD-grade analytical validation of an AXINON® NMR-based ApoB, benchmarked independently against two routine clinical chemistry analyzers, aiming to enable?future?integration into clinical routine diagnostics. Methods NMR analytical experiments for precision, linearity, and method comparison were performed using the AXINON® ApoB research use only modules (numares AG, Regensburg, Germany) at two different sites. Method comparison was performed against two different commercially available clinical analyzers (Thermofisher Optilite and Roche Cobas c501). Samples were derived from clinical residual serum collected in plain serum clot tubes (RED: n=241) or serum separator tubes (SST: n=66). Within-laboratory coefficients of variation (CVWL) and repeatability (CVr) were determined by replicate measures (n=14) on different runs. Linearity was assessed by mixing samples (n=14) with a high and low ApoB concentration at various concentrations. Results Imprecision was determined at various concentrations of ApoB (range 35.5 – 145.5 mg/dL); CVWL was <3.8% and CVr was <2.9%, for all sites and concentrations. The linear slope was between 0.97 and 1.01, bias was <4.5mg/dL and correlation was >0.99 for both sites. The mean absolute error (MAE) was 7 mg/dL compared to Roche and 5.5 mg/dL for Optilite measured ApoB. The percentage of measurements within 15% of Roche ApoB was > 83% Red and >86% for SST: all samples (n=34) were within 15% of Optilite ApoB. Conclusion Our data support that AXINON® NMR-based ApoB shows comparable precision, and concordance with commercially available ApoB immunoassays. ApoB NMR profiling in addition to lipoprotein particle number and lipoprotein size may provide expanded utility for lipid management.