Wockenfus, Amy M.

Abstract Background Hemolysis, a common pre-analytical interferent in clinical laboratory testing, can significantly affect accuracy and reliability of laboratory results. One test particularly susceptible to interference is direct bilirubin (D-bil). For example, during December 2024, 40% (500/1239) of specimens rejected due to hemolysis were orders for D-bil. The recently released Roche (Roche Diagnostics) direct bilirubin reagent (BILD2) has a lower threshold for hemolysis (H-index [HI]=25)) than the previous generation (HI=30). The aims of our study were to (1) establish concentration-specific hemolysis thresholds for D-bil and (2) investigate the instrument’s reduced volume function (dilution) as a possible mitigation strategy for samples with hemolysis indices exceeding the established thresholds. Methods Residual serum specimens from physician-ordered D-bil testing were used and analyzed on Roche cobas c701 and c501 analyzers. The instrument’s decreased volume function, intended for results outside the measuring range, was used as a 1:2 dilution and validated using 9 non-hemolyzed negative control specimens with D-bil results from 9.8-13.4 mg/dL. Recovery within 10% neat value was considered acceptable. EDTA whole blood was used to prepare hemolysate pools by washing red cells and lysing by freezing (-80 °C). Twenty-six serum pools with varying D-bil concentrations (0.2-3.4 mg/dL) were prepared. Each pool was split into 10 aliquots and spiked with increasing amounts of hemolysate, not exceeding 10% serum to interferent ratio. The decreased volume function (dilution) was utilized on a subset of the hemolysate-spiked aliquots (N=55) with D-bil results from 0.2-2.5 mg/dL. HI values were estimated to be 50% of neat HI due to the instrument’s inability to measure indices on specimens tested with the decreased volume function. Acceptance criteria for experiments utilizing hemolyzed specimens were ±0.1 mg/dL or 20% of neat sample. Results All non-hemolyzed specimens tested with the decreased volume function passed within acceptance criteria with average recovery of 109% (range: 106-110%) from undiluted specimens. Serum pools with D-bil <0.3 mg/dL (N=7) spiked with hemolysate (HI range: 7-191) had an average difference of -0.1 mg/dL (range: -0.2-0.0 mg/dL) from non-hemolyzed pools, D-bil pools 0.4-0.9 mg/dL (N=10; HI range: 6-173) had an average difference of -0.2 mg/dL (range: -0.5-0.0 mg/dL), and D-bil pools >1.0 mg/dL (N=9; HI range: 5-182) had an average difference of -20.7% (range –45.5-0.0%). Serum pools with D-bil <0.3 mg/dL (N=23; HI range: 43-191) tested using the decreased volume function had an average difference –0.1 mg/dL (range: -0.2-0.0 mg/dL; HI range: 22-96) from the non-hemolyzed specimens, D-bil pools 0.4-0.9 mg/dL (N=20; HI range: 39-173) had an average difference -0.1 mg/dL (-0.3-0.0 mg/dL; HI range: 19-86), and D-bil pools >1.0 mg/dL (N=12; HI range: 37-182 ) had an average difference of -0.2 mg/dL (-0.5-0.2 mg/dL; HI range: 19-91). Conclusion We established a new hemolysis interference threshold of 75 for samples with D-bil <0.3 mg/dL. Using the decreased volume function, we expanded the hemolysis interference threshold to HI=100 for specimens =0.3 mg/dL. All specimens with HI>100 will result in a recollection. With these changes, we estimate that we can reduce our D-bil recollections by up to 6% over six months.

Abstract Background Community Paramedic (CP) programs use specially trained paramedics to provide healthcare in the community to increase access to care, reduce unnecessary emergency department visits, and improve timeliness of care. Mayo Clinic in Rochester, MN recently launched a CP Program to provide in-home care for patients who require regular intravenous medications, wound care, diuresis for heart failure, medication reconciliation, care plan compliance/education. CP utilizes i-STAT1 CHEM8+ and Lactate (CG4+) testing (Abbott Point of Care, Abbott Park, IL) to make therapy decisions primarily for heart failure patients based on rapid laboratory results. Having results available at the point of care (POC) eliminates delays between testing and treatments, expediting care for the patient. Prior to using i-STAT, CP traveled to the patient’s residence, drew blood tubes, delivered the tubes to Mayo Clinic, waited for test results, returned to the patient’s home, and provided treatment. In this observational study, we assessed the benefit of in-home POC i-STAT1 testing performed by our CP Program to improve patient care and increase efficiency. Methods Patients within a 40-mile radius of Mayo Clinic were eligible to receive CP service. Whole blood venous specimens were collected and tested using the i-STAT1 CHEM8+ metabolic panel cartridge according to manufacturer instructions to measure: ionized calcium, chloride, glucose, hematocrit, total carbon dioxide, blood urea nitrogen, creatinine, potassium, sodium, anion gap while the i-STAT1 CG4+ cartridge measures lactate. The laboratory information system was used to extract laboratory results, and Excel (Microsoft, Redmond, WA) was used to filter data and perform calculations. Results November 2022 through December 2024, CP performed testing with 353 i-STAT cartridges (3862 tests) on 102 unique patients who each had 1-12 separate orders. Patient ages were 25 to 97 years. 41.2% (1590/3862) of the individual results obtained were outside of our reference intervals (23.0% high, 18.0% low), with 10.8% being ionized calcium, 10.2% chloride, 10.3% glucose, 13.0% hematocrit, 7.6% total carbon dioxide, 18.2% blood urea nitrogen, 16.4% creatinine, 6.7% potassium and 6.9% sodium. Additionally, 0.13% of results were critically high (ionized calcium, potassium, and sodium) and 0.10% were critically low (potassium and ionized calcium). Hypokalemic patients were sent to the infusion therapy center for IV potassium. Patients experiencing hyperkalemia were retested and sent to the emergency department (ED). Hyponatremic and hypercalcemic patients were sent to the ED for further treatment. Abnormal (non-critical) results were reviewed by CP personnel to make treatment recommendations or medication adjustments. Conclusion i-STAT1 home testing performed by CP facilitated rapid therapeutic interventions and expedited decision-making. POC testing has increased the group’s efficiency—alleviating the need to transport specimens to the central laboratory and wait on test results before returning to the patient for treatment. Paramedicine emphasizes a proactive and preventative approach to medicine. We anticipate that this model of care and testing will expand to cover other chronic health conditions due to the program’s early success.

Abstract Background The Oncology Department at our institution requested faster turn-around times (TAT) for chemistry testing. Prior to their request, serum separator tubes (SST) were collected and tested in our core laboratory. To accommodate the request, we added plasma total bilirubin and aspartate aminotransferase (AST) to our stat laboratory test menu with collection in plasma separator tubes (PST). Upon implementation of this testing change, we observed an increase in specimen recollection rates due to hemolysis. We systematically evaluated laboratory testing variables that could have contributed to the increase: pneumatic tube transport path, differences in hemolysis measurements between chemistry analyzer models, and specimen types. Previous studies have demonstrated that lithium heparin plasma specimens are more susceptible to hemolysis than serum. Likewise, patients undergoing chemotherapy or radiation therapy may have fragile red blood cell (RBC) membranes, further complicating the issue. Our study*s objective was to assess the impact of changing from SST to PST collections. We conducted a 3-month pilot study to determine if we could reduce our recollection rates by collecting/testing Rapid Serum Tube (RST), while maintaining plasma TAT. Methods We compared recollection rates for specimens collected from the oncology patients and tested in our core laboratory (SST, May-June 2021), stat laboratory (PST, September-November 2022), pilot period in stat lab (RST, January-March 2023), and post-pilot period in stat lab (PST, May-July 2023). Data were extracted from our laboratory information system and recollection rates were calculated using Tableau (Salesforce, Inc, San Francisco, CA). Analysis was performed in Excel (Microsoft, Redmond, WA) using Student’s t-test, with p < 0.05 defined as statistically significant. Results SST specimens collected from oncology patients and tested in the core lab (May-June 2021) resulted in a recollection rate of 0.17% (4/2341). PST specimens sent to the stat lab (Sept-Nov 2022) had an increased recollection rate of 0.90% (55/6129, p-value < 0.001). During the pilot period when RST tubes were used (Jan-Mar 2023), our recollection rate decreased to 0.19% (11/5801, p-value 0.014). After the pilot period ended and PST tubes were again utilized for testing (May-July 2023), the recollection rate again increased to 0.34% (22/6500, p-value 0.019). Conclusion Rapid TAT of laboratory results within specialized-care settings, such as a cancer treatment clinic, is necessary to provide patients with the most effective and personalized treatment regimens. Hemolysis presents a challenge as it generates an analytical issue with the release of contents from RBCs that may spuriously affect the concentration of the analyte being measured, delaying result reporting due to the need for specimen recollection. The data from our study highlight the utility of rapid serum tubes. Not only did they achieve stat TAT that was observed with the use of PST, but they also decreased specimen recollection rates that mirror the low rates observed with the use of SST. Thus, this technology may be an excellent replacement for standard SST when specimen integrity is critical to rapidly reporting accurate test results.

Abstract Background Platelet function tests (PFT) help assess bleeding risk and guide appropriate hemostatic measures in patients on antiplatelet therapy undergoing emergent surgical interventions. Light transmission aggregometry (LTA, BioData Corporation), the gold standard for assessing platelet function, cannot be performed rapidly enough for emergent interventions. In this study, we compared two PFT, Plateletworks (Helena Laboratories) and TEG 6S (TEG, Haemonetics) adenosine diphosphate-(ADP) and arachidonic acid (AA)-induced platelet function, evaluating analytical imprecision and their ability to differentiate healthy controls from patients with acute coronary syndrome (ACS) on dual antiplatelet therapy. Methods Fresh specimens were collected from healthy donors (HD, N=19) and a patient group (PG, N=17) on both aspirin and clopidogrel taken within 24 hours of procedure. Percent aggregation was measured according to manufacturers’ instructions using Plateletworks and TEG, utilizing both AA and ADP and compared to LTA performed on a PAP-8E Platelet Aggregometer. Two separate venipuncture collections from HD were used to obtain repeat measures of Plateletworks and TEG to assess variability in platelet function due to pre-analytical variables. Using a two-way nested ANOVA model on data from HD, we estimated variability between replicates of a single sample (intra-assay imprecision) and between blood draws within a single patient (inter-assay imprecision), reported as coefficient of variation (CV%). Platelet function results were summarized as median (interquartile range [IQR; 25th-75th percentiles]) and compared between groups using nonparametric Wilcoxon rank-sum test. Receiver operating characteristic (ROC) analysis (using duplicate means from first blood draw) was performed. Results Plateletworks AA % aggregation, medians (IQR) were 96.3 (95.3-97.1) for HD and 48.9 (46.8-54.8) for PG (p<0.001); ADP % aggregation were 97.0 (94.5-98.2) and 37.1 (28.0-53.0) for HD and PG, respectively (p<0.001). TEG AA % aggregation was 97.8 (94.4-99.8) for HD and 13.5 (7.9-26.8) for PG (p<0.001); ADP % aggregation was 98.3 (95.3-99.9) for HD and 83.3 (77.8-87.7) for TG (p<0.001). LTA AA % aggregation was 55.0 (44.0-64.8) for HD and 0.0 (0.0-1.5) for PG (p<0.001); ADP % aggregation of 59.0 (40.8-70.8) and 14.5 (4.5-19.5) for HD and PG, respectively (p<0.001). Intra- and inter-assay imprecision estimates (CV%), respectively, in HD were 1.4 and 5.1 for Plateletworks AA, 5.5 and 15.9 for Plateletworks ADP, 3.0 and 0.0 for TEG AA, and 2.6 and 0.8 for TEG ADP. Intra-assay precision estimates for LTA AA and LTA ADP were 19.3 and 8.2. In PG, intra-assay precision was estimated as 7.0 for Plateletworks AA, 9.6 for Plateletworks ADP, 61.3 for LTA AA, 11.9 for LTA ADP, 37.6 for TEG AA, and 4.1 for TEG ADP. In our limited data set, ROC analysis showed optimal cutpoints (sensitivity/specificity) for Plateletworks AA 65.5 (1.0/1.0) and ADP 84.5 (1.0/0.90), TEG AA 87.1 (1.0/1.0) and ADP 92.7 (1.0/1.0), and LTA AA 8.75 (0.94/1.0) and ADP 25.0 (0.82/0.90) Conclusion Plateletworks most effectively distinguished % aggregation between healthy donors and patients on dual antiplatelet therapy. TEG also differentiated the groups, but differences in median ADP-induced aggregation were smaller than with Plateletworks. Both AA and ADP assays on LTA showed more variability than either Plateletworks or TEG.

Abstract Background Rapid testing for Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis may be useful for antibiotic stewardship initiatives. Our institution recently implemented the second-generation Visby Medical Sexual Health Test (Visby Gen2) for rapid diagnosis of STIs in our emergency department. Here we (1) compared result concordance of the (Visby Gen2) to the first-generation Visby Medical Sexual Health Click Test (Visby Gen1), (2) compared assay failure rates of the Visby Gen1 to Gen2 tests, and (3) compared result turnaround time (TAT) for clinically ordered rapid STI tests to central laboratory STI results. Methods Accuracy was assessed using residual clinical samples in Aptima buffer submitted for routine molecular STI testing (C. trachomatis, N. gonorrhoeae, and T. vaginalis) in the central laboratory on the Panther platform (Hologic). Aptima samples were diluted 1:33 in Visby collection buffer prior to testing on the Visby cartridge. Clinically reported results were used as reference results. Diluted samples with discordant results were re-tested on the reference method and the result from the dilution was used in calculations. Assay failure rates were calculated as the number of failed assays compared to the total assays performed. TAT for rapid and central lab testing was calculated as time of sample received in laboratory to time verified in laboratory information system. Results For Visby Gen1 we observed negative concordance of 100% (41/41) for C. trachomatis, 97.5% (39/40) for N. gonorrhoeae, and 97.1% (34/35) for T. vaginalis. Positive concordance was 91.7% (11/12) for C. trachomatis, 100% (11/11) for N. gonorrhoeae, and 100% (17/17) for T. vaginalis. For Visby Gen1 we observed a 10.5% (12/114) cartridge failure rate. For Visby Gen2, we observed negative concordance of 100% (59/59) for C. trachomatis, 100% (63/63) for N. gonorrhoeae, and 100% (55/55) for T. vaginalis while positive concordance was 100% (10/10) for C. trachomatis, 100% (6/6) for N. gonorrhoeae, and 90.9% (10/11) for T. vaginalis. The Visby Gen2 assay displayed a 4.9% (4/81) cartridge failure rate. Six weeks after implementing the Visby Gen2 assay in our ED, rapid STI panel TAT was 0.48 hours on average (n=20). In the central laboratory the average TAT was 22.31 hours (n=7892). Conclusions Assay concordance to reference method was similar for Visby Gen1 and Gen2 assays. The cartridge failure rate improved by 46.7% with the Gen2 assay which should decrease the need to repeat testing due to assay failure. Result TAT decreased by 97.8% when comparing rapid Visby results to central laboratory. Therefore, Visby STI testing using the Gen2 assay can provide accuracy and rapid results likely to facilitate more rapid patient management.

Abstract Background Managing preanalytical variables is critical to providing quality laboratory test results. However, this can be a challenge for laboratory staff, particularly with manual detection of interfering substances and complicated workflows. For coagulation testing, we assess specimen integrity and acceptability by visual checks and quantification of interfering substance on a chemistry analyzer. To improve this subjective process, we evaluated the technical performance of a new model of coagulation analyzer with automated preanalytical specimen integrity detection. Our objective was to determine if we could reduce the number of specimens requiring visual inspection/off-analyzer interference testing in order to simplify our testing workflow. Methods Citrated plasma specimens received in the Hospital Clinical Laboratory at Mayo Clinic (Rochester, MN) were tested on the TOP ACL 500 or TOP ACL 550 Series Coagulation analyzers (Werfen, Boston, MA) according to manufacturer’s instruction. Specimens tested on the TOP 500 were visually inspected for hemolysis, icterus, and lipemia (HIL). If the technologist detected a possible interferent, an aliquot of plasma was analyzed on our cobas c501 chemistry analyzer (c501) (Roche Diagnostics, Indianapolis, IN) to obtain HIL values. Laboratory-established or manufacturer-defined interference thresholds were applied in determining specimen acceptability. For samples tested on the TOP 550, specimen integrity was assessed by the instrument’s automated interference detection module. The analyzer reported HIL as an “interference cloud” or estimated range, rather than a single value like the c501. HIL values were estimated by visual assessment of the low end of the “interference cloud”. Values were confirmed on the c501 only for specimens with an “interference cloud” at/exceeding the test-specific interference thresholds. We analyzed data from a 2-month period pre- (TOP 500) and post-implementation (TOP 550). The percent of specimens requiring quantitation/confirmation on the c501 was calculated. Statistical significance was calculated using the Chi-squared test where significance was defined as p<0.01. Correlation between c501 and TOP 550 estimated HIL values was evaluated. Results A total of 2.2% (171/7605) and 1.3% (113/8983) of specimens tested on the TOP 500 and TOP 550, respectively, required HIL measurements on the c501 (p<0.001). Of those samples, 8.2% (14/171) and 14.2% (16/113) from the TOP 500 and TOP 550, respectively, had HIL values above the interference thresholds and were rejected by the laboratory. Comparison of the estimated HIL values from the “interference cloud” and from the c501 resulted in slopes (Pearson correlation coefficients) of: H 1.56 (0.77), I 0.67 (0.97), and L 1.35 (0.99). Conclusions In comparison to our workflow with visual assessment of interference, use of the automated interference detection functionality on the TOP 550 instrument resulted in a lower percentage of specimens requiring HIL measurements on the chemistry analyzer. Agreement between interference measurements obtained on the c501 and the TOP 550 was moderate where TOP 550 overestimated the degree of hemolysis and lipemia and underestimated icterus. Implementation of automated interference detection on the TOP 550 analyzer improved our workflow by eliminating the need for tedious and subjective visual checks and reducing the percentage of specimens requiring additional HIL measurements.

Abstract Background Turnaround time (TAT), defined as time of collection to time of result verification, is monitored monthly for cardiac Troponin (cTnT). Within our STAT laboratory, our TAT goal is 85% of cTnT results verified within 45 min. In October 2021, our lab began observing an increase in TAT. A quality improvement project was launched to identify a root cause and possible solutions. Methods cTnT TAT data from the Hospital Clinical Laboratory (STAT lab) at Mayo Clinic, Rochester, MN was extracted from our Laboratory Information System (LIS) using Tableau (Salesforce Inc., Seattle, WA). The data were categorized into three components: collection time, in lab processing and testing time, and time to result verification. Goal metrics for each component are: collection <10 min, in lab processing and testing <25 min, and result verification to LIS <5 min. The average time for each component and percentage not meeting TAT goals were calculated in Microsoft Excel. TAT while performing manual verification of results (January 2022) and after autoverification was implemented (December 2022) were compared. Results Prior to implementation of cTnT autoverification, total orders for January 2022 were 1408 with 82.0% meeting TAT of 45 min. Of the 18.0% not meeting TAT, 207 (14.7%) orders exceeded goals for one or more components (percentages do not total 100%): collection delays 131 (63.0%), in lab processing and testing delay 175 (85.0%), and delay in result verification to LIS 80 (39.0%). For those orders not meeting the 45 min TAT goal, mean times were 17.6, 40.3, and 8 min for collection time, in lab processing and testing, and result verification to LIS, respectively. Post implementation of autoverification, total orders for December 2022 were 1444 with 88.6% meeting TAT of 45 min. Of the 11.4% not meeting TAT, 93 (6.4%) orders were outside goals for multiple components: collection delays 51 (55.0%), in lab processing and testing delay 67 (72.0%), and result verification to LIS 0 (0.0%) orders. For those orders not meeting the 45 min TAT goal, mean times 16.6, 39.7, and 0 min for collection time, in lab processing and testing, and result verification to LIS, respectively. Conclusion Achieving TAT goals agreed upon by the laboratory and clinical practice is critical to quality patient care. An investigation into our delayed TAT for cTnT highlighted several opportunities for intervention within the control of the lab. We chose to implement autoverification of results to easily and consistently eliminate the time required for manual result verification. TAT was improved by 6.6% (82.0% to 88.6%) through autoverification of results, allowing technologists to focus on other clinical work.

Abstract Background Analytical outliers (fliers) occur with most troponin methods and can adversely affect patient management. We compared the analytical outlier rates for the Roche 5th generation Troponin T STAT (cTnT) reformulated (biotin-insensitive) reagent using a Cobas e601 analyzer (Indianapolis, IN) to rates observed in a previous study using the biotin-sensitive reagent on a Cobas e411 analyzer. Methods Plasma separator tubes (PST) were collected from hospital patients with orders for clinical cTnT testing. PST samples were centrifuged for 3 min at 4000g and analyzed using the biotin-insensitive cTnT Gen 5 assay on a Roche Cobas e601 immunoassay system. If samples displayed measurable cTnT Gen 5 (≥6 ng/L), samples were stored at 2–8 °C within 2 h of initial measurement (N = 2555). Within 24 h of initial analysis, samples were warmed to room temperature, aliquoted, re-centrifuged at 4000g for 3 min, and cTNT was re-measured on the same analyzer. Outlier rates were compared to a previous study (N = 1997) using nearly identical study design but using biotin-sensitive Roche 5th Gen cTnT reagent on an e411 analyzer. We defined analytical outliers by three methods: Repeat value (after aliquoting and re-centrifugation) that differed from the initial value for all samples with measurable cTnT by a critical difference (CD): where CD = z × √2 × SDanalytical, with a z-value of 3.719 and using SD from best fit line of precision vs cTnT concentration. Precision experiments were performed using four plasma pools in 5 × 5 precision experiment on the e411 analyzer. Using the same CD but considering only initial cTnT values <100 ng/L, those are most likely to be clinically significant or lead to misinterpretation. Using CD for initial values <100 ng/L, and a fixed 10% difference between replicates for initial values ≥100 ng/L, accounting for our practice of reporting the cTnT “delta” in percent (rather than absolute) for values ≥100 ng/L. Comparisons of outlier rates between the biotin-sensitive and biotin-insensitive reagents were performed using Pearson’s chi-squared test. Results Using the CD the total number of outliers that were observed for the biotin-insensitive reagent on the e601 was 208/2555 (8.1%), compared to 68/1997 (3.4%) on the biotin-sensitive reagent measured on the e411 (P < 0.0001). Outliers were observed in 138 (6.4%) of samples with initial values < 100 ng/L using the biotin-insensitive reagent on the e601 compared to 45 (2.6%) of such samples on the e411 (P < 0.0001). Using the Z score method to define outliers for initial values <100 ng/L and a fixed 10% to define outliers for initial values ≥100 ng/L, the outlier rate was 151 (5.9%) for the biotin-insensitive reagent on the e601 compared to 53 (2.7%) on the e411 (P < 0.0001). Conclusions Analytical outliers occurred more frequently using the reformulated (biotin-insensitive) reagent on the Roche Cobas e601 analyzer, compared to outlier rates observed for biotin-sensitive reagent on the Cobas e411.

Abstract Background Hemolysis is a pre-analytic issue that challenges clinical laboratories. When a specimen with significant hemolysis is obtained in our laboratory, tests where the hemolysis threshold is exceeded are not reported and blood is recollected. Unfortunately, in a subset of patients, the recollected specimen is also hemolyzed (termed “recurrent hemolysis”). In these cases, the second recollection utilizes special collection and handling protocols (i.e., hand-carried to lab, plasma collection, etc.) to mitigate preventable causes of hemolysis. Lipemia is also a known contributor to specimen hemolysis. Mayo Clinic Rochester experienced an increased rate of hemolysis as well as recurrent hemolysis during the height of the COVID-19 pandemic (January 2022). The objective of this study was to investigate the increased rate of recurrent hemolysis and compare to a rate prior to the COVID-19 pandemic (January 2019). Methods Retrospective data analysis was performed for January 2019 (negative control) and January 2022. The number of Mayo Clinic Rochester hospital admissions, admitting diagnosis, medications administered, and number of test collections performed were obtained using reporting functionality in our Electronic Health Record (EHR), Epic. The Laboratory Information System, SoftLab, was utilized to obtain recollection rates due to hemolysis. Data were normalized to total patient admissions for the specified period to account for inter-year variability. R/R Studio was utilized to analyze and visualize the data. Pearson’s Chi-squared test for independence was performed on categorical variables (significance defined as P < 0.05). Results A 28% decrease in hospital admissions (n = 3958:Jan-22 vs n = 5517:Jan-19) and a 23% decrease in total specimens collected on hospitalized patients (n = 40 557:Jan-22 vs n = 52 373:Jan-19) was observed between Jan-19 to Jan-22. However, the laboratory observed a 6% increase in hemolyzed specimens (n = 256:Jan-22 vs n = 241:Jan-19). Recurrent hemolysis occurred in 24% (n = 62/256) of Jan-22 and 17% (n = 43/241) of Jan-19 hemolyzed specimens and required special handling protocols. COVID positive patients comprised 48% (n = 30/62) of those requiring special handling protocols in Jan-22. Further examination revealed 34% (n = 21/62) of Jan-22 and 12% (n = 5/43) of Jan-19 cases of recurrent hemolysis were due to lipemia (P < 0.01). Chart review highlighted a potential source of lipemia from the administration of propofol, a lipophilic sedative emulsion. Of those COVID positive cases with recurrent hemolysis due to lipemia (n = 15/30), 93% (n = 14/15) were receiving propofol at the time of collection (P < 0.001). Conclusion We observed increased rates of specimen hemolysis during the COVID-19 pandemic. While most hemolysis resolves upon specimen recollection, patients with recurrently hemolyzed specimens often require special specimen collection and handling protocols to mitigate hemolysis. Approximately half of the recurrent hemolysis cases in Jan 2022 were COVID-19 positive patients. Lipemia-induced hemolysis was also more frequent in this patient population presumably due to the administration of propofol, a lipophilic emulsion sedative commonly used for COVID positive patients requiring sedation and ICU-level care. It is critical to understand the variety of factors which may contribute to recurrent hemolysis, as intervening with specialized collection and handling protocols to reduce observed pre-analytical hemolysis is required to provide accurate and timely laboratory results.

Abstract Objectives To evaluate the analytical and clinical performance characteristics of the fifth-generation troponin T reagent. Methods Troponin T was measured in 2,332 paired serum and plasma samples from emergency department and hospital patients using the fourth- and fifth-generation reagents. Testing was repeated after recentrifugation to determine the frequency of analytical outliers and percentage of patients with elevated values for each assay. We conducted separate experiments to determine the effects of biotin and hemolysis interference, as well as measure interinstrument variability, for fifth-generation troponin T. Results Analytic outliers occurred more frequently using the fifth-generation reagent (3.4%) compared with the fourth-generation reagent (1.0%). The frequency of elevated troponin T above the 99th percentile upper reference limit was 26% for the fourth-generation reagent and 52% for the fifth-generation reagent. Clinically significant assay interference by biotin was observed at 20 ng/mL, but hemolysis interference was not observed until an H index of 150. Instrument-to-instrument variability between e411 and e601/602 instrument platforms is predicted to confound clinical interpretation of troponin changes. Conclusions Analytical outliers and instrument-to-instrument variability are the two analytical variables most likely to confound interpretation of changes in fifth-generation troponin T results over time.