Lithium Heparin Plasma Research Articles

Evidence for stability of cardiac troponin T concentrations measured with a high sensitivity TnT test in serum and lithium heparin plasma after six-year storage at-80 °C and multiple freeze-thaw cycles.

As high-sensitivity cardiac troponin T (hs-cTnT) is making the transition from diagnostic to prognostic use, a long-term stability study of 5th generation hs-cTnT according to EFLM CRESS recommendations was set up for investigation of frozen clinical specimens (two matrices). Study samples collected in serum tubes and lithium heparin tubes with gel from patients admitted for suspected minor myocardial damage were measured directly after completion of the study (0 years), and after 3-year and 6-year storage at-80 °C, and recovery of hs-cTnT concentrations after long-term storage (%hs-cTnT concentration compared to 0-year) was calculated. Hs-cTnT changes were also compared to decisive delta changes, such as the ones proposed in the ESC NSTEMI 0 h/1 h algorithm (<3 or >5 ng/L for ruling out and ruling in suspected NSTEMI patients). Eighty-six patients were included in the study, whereof 28 both lithium heparin plasma and serum samples were collected simultaneously, in others only serum (n=30) or plasma (n=28). Multiple aliquots per patient were made, so that 479 serum and 473 plasma samples were available for analysis. Across the overall hs-cTnT measuring range, median recovery after 6 years was 105.4 % and 106.2 % for serum and plasma, respectively. Based on these decisive delta changes, serum showed consistent results upon long term storage (max 0.8 % of samples above delta threshold of >5 ng/L) as compared to heparin plasma (up to 19.2 % of samples above threshold). Over 6 years of storage at-80 °C, recovery of hs-cTnT in serum and heparin plasma was similar and within common lot-to-lot variation. Yet, when evaluating absolute delta increments around hs-cTnT clinical decision points, long-term stored sera displayed better clinical performance compared to heparin plasma samples.

Comparison of multiple high sensitivity cardiac troponin assays for early low risk rule out of myocardial infarction: SCORECARD

Abstract Background/Introduction The use of a single low high-sensitivity cardiac troponin measurement to rule out myocardial infarction (MI) at presentation is advocated by international guidelines. Studies have not systematically compared high-sensitivity cardiac troponin (hs-cTn) I and T assays to determine which values should be used to rule out MI in patients with suspected acute coronary syndrome. Methods In a pooled analysis from three prospective observational cohort studies the lowest cTn concentration was determined that gave a negative predictive value (NPV) of ≥99.5% for MI or death at 30 days on presentation to the emergency department. EDTA or lithium heparin plasma or serum samples collected at presentation were measured using five hs-cTnI assays (Abbott ARCHITECT i2000, Beckman Coulter Access 2, Siemens Atellica IM, Ortho-Clinical Diagnostics VITROS 5600, LSI Medience PATHFAST) and one hs-cTnT assay (Roche Cobas e411). The diagnostic outcome of MI or death at 30 days was adjudicated according to the Fourth Universal Definition of MI. Optimal thresholds were determined to identify the highest proportion of patients that could be considered for discharge for a NPV of ≥99.5% for each assay. Results Among 941 patients, MI or death at 30 days occurred in 113 (12%). Optimized thresholds varied between assays ranging from &amp;lt;2 to &amp;lt;7 ng/L (Table) that identified between 22% and 60% of patients as low risk (0-1%) for MI or death at 30 days. Conclusions Our data identify differences in the effectiveness of thresholds between hs-cTnI and hs-cTnT assays for the same safety performance to rule out MI on presentation using a single measurement. In some cases, these thresholds differ from those used in clinical practice. Due to lack of assay standardization, optimal decision thresholds should be defined and validated for each high sensitivity cTn assay.

A-009 Analytical Characterization of a Novel NT-proBNP Assay on a Central Laboratory Platform

Abstract Background N-terminal pro-B-type Natriuretic Peptide (NT-proBNP) or B-type Natriuretic Peptide (BNP) assay(s) are widely measured with a Class 1, Level of Evidence A recommendation in professional heart failure (HF) guidelines for diagnosis and prognosis. We present the analytical characteristics of the first NT-proBNP assay on Beckman Coulter platforms. Methods Measurements were conducted with the Access NT-proBNP assay, a one-step sandwich immunoenzymatic assay using monoclonal capture and detection antibodies, on the DxI 9000 Immunoassay Analyzer with Lithium Heparin (LiHep) plasma samples. Performance was characterized according to CLSI guidelines for: Limit of Blank (LoB), Limit of Detection (LoD), Limit of Quantitation (LoQ), linearity, imprecision (repeatability, reproducibility) and matrix comparison with LiHep, EDTA and serum. Reference intervals (RI) were evaluated in a healthy, adult U.S. population comprised of 675 subjects with 54.6% females, 79.1% White and 15.1% Black individuals. Exclusion criteria included elevated cardiac troponin, abnormal eGFR and cardiac medications. The 97.5th percentile RI upper limit was defined for age-stratified ranges of &amp;lt;50, 50-75, and &amp;gt;75 years old. Results Performance was LoB=1.1ng/L; LoD=4.8ng/L; LoQ=4.8ng/L; linearity=35,000ng/L. Repeatability ranged from 1.5%-3.5% and reproducibility from 2.3%-7.9% in seven samples ranging from 38ng/L to 23,848ng/L. Matrix measurement regression (n=68) yielded slopes of 1.00, 1.01; intercepts -0.03 to -2.63; r=0.98. Table 1 shows that NT-proBNP values increase with age and women generally have higher values than men. Conclusions The LoB, LoD and LoQ demonstrate highly sensitive low-end characteristics. Repeatability and reproducibility show excellent performance across a wide measurement range. NT-proBNP values are known to be age dependent, and the age-stratified 97.5th percentile RI upper limits were 162 ng/L for &amp;lt;50 years, 311 ng/L for 50-70 years, and 457 ng/L for &amp;gt;75 years. This novel Access NT-proBNP assay offers robust analytical performance as an aid to clinical HF management in acute settings.

A-056 Investigating Iodine Contrast Contamination in Cortisol and Aldosterone Samples

Abstract Background Primary aldosteronism (PA) is a condition characterized by hypertension resulting from excess secretion of aldosterone. PA caused by a unilateral aldosterone-producing adenoma can be treated with adrenalectomy but requires diagnosis by adrenal vein sampling (AVS). In this procedure, intravenous cosyntropin is administered to stimulate adrenal cortical secretion, followed by obtaining samples from the right and left adrenal veins and IVC. Laterization index is calculated by obtaining the aldosterone:cortisol ratio for each side, with a ratio cutoff ≥3 is used for confirmation. Iodinated contrast media facilitates visualization of catheter positioning during AVS and sometimes results in contamination of samples, evidenced by abnormal gel separator flotation (i.e. gel above plasma). This study had two aims: 1) to determine at what concentration contrast dye causes gel flotation and 2) discern whether contrast media interferes with our cortisol or aldosterone assays. Methods Gel flotation studies were performed by spiking pooled plasma samples with iohexol contrast media (Omnipaque 240, GE Healthcare) at concentrations ranging from 3%-10% v/v and aliquoting into fresh lithium heparin plasma separator tubes (BD, PSTs). Samples were then centrifuged and visually inspected for abnormal gel flotation. Contrast interference studies were performed using three pools of low (5 µg/dL), medium, (30 µg/dL), and high (55 µg/dL) cortisol concentrations. Sample pools were diluted with 20% contrast media or saline (control) and subsequently mixed at different ratios to create a range of dye concentrations (0.5%-18% v/v). Each mixture was assayed in triplicate for cortisol and aldosterone on a cobas e602 (Roche Diagnostics) and LIAISON XL (DiaSorin) immunoanalyzer, respectively. The total allowable error (TEa) was ±0.4 μg/dL or ±20% for cortisol and ±2 ng/dL or ±20% for aldosterone. Results Flotation of the gel separator was observed at a dye concentration of 4.5% v/v and greater. For the cortisol interference study, the bias was &amp;lt;5% for the three pools at all contrast media concentrations. Aldosterone was also measured in these pools, as bias could affect ratios calculated for PA. Aldosterone interference occurred at contrast dye concentrations ranging from 12%-20% v/v. An average positive bias of 34% was observed in aldosterone samples spiked with contrast media relative to the saline control. Compared to sample pool controls without added saline or dye, measurements for cortisol and aldosterone were 19%-22% and 16-25% lower in media- and saline-spiked samples (20% v/v), respectively, indicating a logical dilution effect. Conclusions Contrast dye contamination of AVS specimens can cause gel flotation in lithium heparin PSTs, preventing their analysis. The presence of contrast media at certain concentrations interfered with the DiaSorin aldosterone assay, leading to falsely elevated results. No cortisol assay interference occurred in the presence of contrast media but results were falsely decreased due to sample dilution. Samples collected during AVS may be contaminated with contrast dye causing gel flotation to occur. This is indicative of a minimum contrast media concentration of 4.5% v/v. Aldosterone:cortisol ratios may be inaccurate due to the positive aldosterone immunoassay bias with contrast media contamination. Care should be taken when reporting and interpreting AVS results with suspected contamination.

A-107 Sample Matrix Matters: A Precision Study of BioRad, TechnoPath, and Patient Pooled Samples Across 20 High Volume Chemistries and Immunoassays

Abstract Background BioRad is a major provider of QC materials in the US with robust peer data, and Technopath has emerged as a recent competitor, especially on cost. While many factors are considered when selecting QC materials, primary considerations include commutability, matrix effects, decision levels, and acceptability limits. A couple studies comparing BioRad and Technopath QC performance were published in recent years. However, none have compared performance to patient-pooled samples. We undertook a comparison of BioRad/Technopath QC performance, with the addition of patient-pooled samples in order to assess potential matrix effects. Methods We compared precision for 20 high-volume chemistry/immunoassay tests (Table 1) across two levels of BioRad and Technopath QC and a patient pooled sample over 7 days on 2 Abbott Alinity-i and 4 Alinity-C instruments. Each immunoassay control level was run 5 times/day across 10 tests and 7 days per instrument, (i.e., 700 results/level), and the same for chemistry controls (1,400 results/level). Lithium-heparin plasma patient-pool was prepared by obtaining sufficient volume and preparing daily frozen aliquots (i.e., 1400 immunoassay and 2800 chemistry results). Results BioRad and Technopath Chemistry QCs were highly comparable with all levels demonstrating &amp;lt;1% CV difference. Notably, CO2, B12, FT4 pooled-patient CVs were &amp;gt;2% lower than the best performing high control. Additionally, greater differences in performance were observed across immunoassay controls with high BioRad QC performing better for 7 tests. Conclusions Chemistry QC for Technopath and BioRad are largely comparable (i.e., CV differences &amp;lt;1%). Overall, BioRad immunoassay control performance was slightly to somewhat better (i.e., B12, CA125, and CA15-3). B12 and CO2 were particularly unstable (as reflected by patient-pool CVs). That said, differences in performance were not untenable and could be handled based on a tailored approach of extending QC limits if assay/instrument performance allows, and/or changing control material or reagents on a tighter schedule.

Preanalytic Integrity of Blood Samples in Uncrewed Aerial Vehicle (UAV) Medical Transport: A Comparative Study

The integration of unmanned aerial vehicles or uncrewed aerial vehicles (UAVs)—commonly known as drones—into medical logistics offers transformative potential for the transportation of sensitive medical materials, such as blood samples. Traditional car transportation is often hindered by traffic delays, road conditions, and geographic barriers, which can compromise timely delivery. This study provides a comprehensive analysis comparing high-speed drone transportation with traditional car transportation. Blood samples, including EDTA whole blood, serum, lithium-heparin plasma, and citrate plasma tubes, were transported via both methods across temperatures ranging from 4 to 20 degrees Celsius. The integrity of the samples was assessed using a wide array of analytes and statistical analyses, including Passing–Bablok regression and Bland–Altman plots. The results demonstrated that drone transportation maintains blood sample integrity comparable to traditional car transportation. For serum samples, the correlation coefficients (r) ranged from 0.830 to 1.000, and the slopes varied from 0.913 to 1.111, with minor discrepancies in five analytes (total bilirubin, calcium, ferritin, potassium, and sodium). Similar patterns were observed for EDTA, lithium-heparin, and citrate samples, indicating no significant differences between transportation methods. Conclusions: These findings highlight the potential of drones to enhance the efficiency and reliability of medical sample transport, particularly in scenarios requiring rapid and reliable delivery. Drones could significantly improve logistical operations in healthcare by overcoming traditional transportation challenges.

A new assay falsely increases lactate dehydrogenase in plasma but not in serum

IntroductionSerum is the International Federation of Clinical Chemistry (IFCC)-recommended matrix for the measurement of lactate dehydrogenase (LD); however, many laboratories opt for lithium heparin plasma to achieve quicker turnaround times and minimize tube usage.When introducing the new Sigma-Strong IFCC-recommended LDH2 assay from Abbott Laboratories on lithium-heparin collected samples, we observed a rise in the patient median LD activity as well as several samples exhibiting falsely elevated values. Materials and methods120 + serum and plasma samples from consenting patients were collected and evaluated for complete blood count and lactate dehydrogenase using two different assays. Aggregated patient results before and after introduction of the LDH2 assay were compared. ResultsMean LD was 14% higher in plasma than in serum when using the LDH2 assay but only 5% higher when using the previous LDH legacy assay from Abbott Laboratories. Similarly, platelets and leukocytes were 10–30 times higher in plasma than in serum. Aggregated lactate dehydrogenase patient results demonstrated a dramatic increase in patient median following introduction of the LDH2 assay. Various experiments were tried to reduce cellular interference, but the only viable solution we found, apart from reverting to the LDH legacy assay, was to utilize serum tubes. ConclusionWe conclude that lithium-heparin plasma leads to falsely elevated lactate dehydrogenase activity when using the LDH2 assay. These errors can be prevented by using serum collected in gel separator tubes.

A Comparison Study: Possible Bias in Troponin I Measurement Obtained with a Point of Care Testing and a Central Laboratory Analyzers Employing Different Biological Matrices and Anticoagulants.

high-sensitive cardiac TroponinI (hs-cTnI) is widely used for diagnosis of acute coronary syndromes. The latest recommendation for hs-cTnI determination is the protocol 0-1 h finalized to improve the rule out accuracy of the test. A Point of Care Testing able to guarantee these performances could be very useful due to reducing the turnaround time and ruling out patients suspected of ACS, especially by using biological matrices that are not required for centrifuge. The aim of our work is to compare the results for hs-cTnI obtained using different biological matrices and anticoagulants, obtained between Atellica® VTLi hs-cTnI POCT and Access AccuTnI+3 DxI800 performances, in order to establish a possible bias derived directly from these pre-analytical conditions. Li-heparinized pool samples were primary employ for hs-cTnI with Atellica® VTLi as whole blood, then centrifuged and tested on Atellica® VTLi and DxI800. K3EDTA pool samples were centrifuged and measured on DxI800 too. A comparison of methods was performed according to CLSI_EP-09A2 protocol. Constant and proportional errors were investigated with Deming regression. Bias between methods was evaluated with the Bland Altman test. comparing whole blood lithium heparin results obtained with Atellica versus lithium heparin and K3EDTA plasma tested on DxI 800, the Deming regression revealed a proportional error, whereas in both cases Bland Altman highlighted a minimal underestimation. A similar performance was revealed when considering plasma lithium heparin tested on Atellica versus lithium heparin and K3EDTA plasma obtained with DxI800, confirming the same underestimation. Considering values close to the cut off, no significant differences were found. in the laboratory, the estimation of the bias of two different analyzers is pivotal. Once more this is crucial when different biological matrices and anticoagulants are employed for the analysis. Our study demonstrates that no significant differences among the two matrices are present when comparing Atellica and DxI800 performances.

Differences in Cardiac Troponin T Composition in Myocardial Infarction and End-Stage Renal Disease Patients: A Blood Tube Effect?

Cardiac troponin T (cTnT) is key in diagnosing myocardial infarction (MI) but is also elevated in end-stage renal disease (ESRD) patients. Specific larger cTnT proteoforms were identified for the acute phase of MI, while in serum of ESRD patients solely small cTnT fragments were found. However, others allocated this to a pre-analytic effect due to abundant thrombin generation in serum. Therefore, we investigated the effect of various anticoagulation methods on cTnT composition and concentration and compared the cTnT composition of MI and ESRD patients. The agreement of cTnT concentrations between simultaneously collected serum, lithium-heparin (LH) plasma, and ethylenediaminetetraacetic acid (EDTA) plasma was studied using the high-sensitivity (hs-)cTnT immunoassay. cTnT proteoform composition was investigated in a standardized time-dependent manner through spike experiments and in simultaneously collected blood matrixes of MI and ESRD patients. Excellent hs-cTnT concentration agreements were observed across all blood matrixes (slopes > 0.98; 95% CI, 0.96-1.04). Time-dependent degradation (40 kDa intact:29 kDa fragment:15 to 18 kDa fragments) was found in LH plasma and EDTA plasma, and serum in ratios (%) of 90:10:0, 0:5:95, and 0:0:100, respectively (48 h after blood collection). Moreover, gel filtration chromatography (GFC) profiles illustrated mainly larger cTnT proteoforms in MI patients, while in ESRD patients mainly 15 to 18 kDa fragments were found for all matrices. The extent of cTnT degradation in vitro is dependent on the (anti)coagulation method, without impacting hs-cTnT concentrations. Furthermore, mainly larger cTnT proteoforms were present in MI patients, while in ESRD patients mainly small 15 to 18 kDa cTnT fragments were found. These insights are essential when developing a novel hs-cTnT assay targeting larger cTnT proteoforms.

Generation of Rapid and High-Quality Serum by Recombinant Prothrombin Activator Ecarin (RAPClot™).

We recently reported the potential application of recombinant prothrombin activator ecarin (RAPClot™) in blood diagnostics. In a new study, we describe RAPClot™ as an additive to develop a novel blood collection prototype tube that produces the highest quality serum for accurate biochemical analyte determination. The drying process of the RAPClot™ tube generated minimal effect on the enzymatic activity of the prothrombin activator. According to the bioassays of thrombin activity and plasma clotting, γ-radiation (>25 kGy) resulted in a 30-40% loss of the enzymatic activity of the RAPClot™ tubes. However, a visual blood clotting assay revealed that the γ-radiation-sterilized RAPClot™ tubes showed a high capacity for clotting high-dose heparinized blood (8 U/mL) within 5 min. This was confirmed using Thrombelastography (TEG), indicating full clotting efficiency under anticoagulant conditions. The storage of the RAPClot™ tubes at room temperature (RT) for greater than 12 months resulted in the retention of efficient and effective clotting activity for heparinized blood in 342 s. Furthermore, the enzymatic activity of the RAPClot™ tubes sterilized with an electron-beam (EB) was significantly greater than that with γ-radiation. The EB-sterilized RAPClot™ tubes stored at RT for 251 days retained over 70% enzyme activity and clotted the heparinized blood in 340 s after 682 days. Preliminary clinical studies revealed in the two trials that 5 common analytes (K, Glu, lactate dehydrogenase (LD), Fe, and Phos) or 33 analytes determined in the second study in the γ-sterilized RAPClot™ tubes were similar to those in commercial tubes. In conclusion, the findings indicate that the novel RAPClot™ blood collection prototype tube has a significant advantage over current serum or lithium heparin plasma tubes for routine use in measuring biochemical analytes, confirming a promising application of RAPClot™ in clinical medicine.

Evaluation of Age and Sex Differences in Contemporary versus High-Sensitivity Troponin I Measurement in Hospitalized Patients.

Background: With the transition from the contemporary (cTnI) to high-sensitivity troponin assay (hs-cTnI), concerns have arisen regarding the diagnostic differences between these two assays due to analytical distinctions. This study aims to evaluate the age and sex differences between these two assays, as well as the differences resulting from using two different 99th percentile values of the high-sensitivity troponin assay. Method: A retrospective observational study was conducted at an academic medical center, encompassing a total of 449 lithium heparin plasma samples included in the dataset. Both contemporary and high-sensitivity troponin were simultaneously measured using Siemens ADVIA Centaur analyzers. Two sets of sex-specific 99th percentile URLs from the Siemens study (cutoff-1) and Universal Sample Bank data (cutoff-2) were used for the data analysis. Results: The use of cutoff-1 or cutoff-2 had a negligible impact on troponin classification. Troponin elevation significantly increased in individuals > 50 years old for males and >40 years old for females, with both troponin assays. A receiver operating characteristic analysis did not find significant differences between the two assays. The Kaplan-Meier curves showed no differences in survival in cTnI according to the non-sex-specific 99th URL or hs-cTnI (cutoff-2) but showed a slight difference in survival in hs-cTnI (cutoff-1). Conclusions: Overall, there were no significant differences in age and sex in the diagnostic performance between the contemporary and high-sensitivity troponin assays. Selection criteria for the establishment of the 99th percentile URL should be standardized to avoid the misinterpretation of the troponin results.

Characterization of the plasma proteome from healthy adult dogs.

Bloodwork is a widely used diagnostic tool in veterinary medicine, as diagnosis and therapeutic interventions often rely on blood biomarkers. However, biomarkers available in veterinary medicine often lack sensitivity or specificity. Mass spectrometry-based proteomics technology has been extensively used in the analysis of biological fluids. It offers excellent potential for a more comprehensive characterization of the plasma proteome in veterinary medicine. In this study, we aimed to identify and quantify plasma proteins in a cohort of healthy dogs and compare two techniques for depleting high-abundance plasma proteins to enable the detection of lower-abundance proteins via label-free quantification liquid chromatography-mass spectrometry. We utilized surplus lithium-heparin plasma from 30 healthy dogs, subdivided into five groups of pooled plasma from 6 randomly selected individuals each. Firstly, we used a commercial kit to deplete high-abundance plasma proteins. Secondly, we employed an in-house method to remove albumin using Blue-Sepharose. Among all the samples, some of the most abundant proteins identified were apolipoprotein A and B, albumin, alpha-2-macroglobulin, fibrinogen beta chain, fibronectin, complement C3, serotransferrin, and coagulation factor V. However, neither of the depletion techniques achieved significant depletion of highly abundant proteins. Despite this limitation, we could detect and quantify many clinically relevant proteins. Determining the healthy canine proteome is a crucial first step in establishing a reference proteome for canine plasma. After enrichment, this reference proteome can later be utilized to identify protein markers associated with different diseases, thereby contributing to the diagnosis and prognosis of various pathologies.

Plasma and serum metabolic analysis of healthy adults shows characteristic profiles by subjects’ sex and age

IntroductionPre-analytical factors like sex, age, and blood processing methods introduce variability and bias, compromising data integrity, and thus deserve close attention.ObjectivesThis study aimed to explore the influence of participant characteristics (age and sex) and blood processing methods on the metabolic profile.MethodA Thermo UPLC-TSQ-Quantiva-QQQ Mass Spectrometer was used to analyze 175 metabolites across 9 classes in 208 paired serum and lithium heparin plasma samples from 51 females and 53 males.ResultsComparing paired serum and plasma samples from the same cohort, out of the 13 metabolites that showed significant changes, 4 compounds related to amino acids and derivatives had lower levels in plasma, and 5 other compounds had higher levels in plasma. Sex-based analysis revealed 12 significantly different metabolites, among which most amino acids and derivatives and nitrogen-containing compounds were higher in males, and other compounds were elevated in females. Interestingly, the volcano plot also confirms the similar patterns of amino acids and derivatives higher in males. The age-based analysis suggested that metabolites may undergo substantial alterations during the 25-35-year age range, indicating a potential metabolic turning point associated with the age group. Moreover, a more distinct difference between the 25–35 and above 35 age groups compared to the below 25 and 25–35 age groups was observed, with the most significant compound decreased in the above 35 age groups.ConclusionThese findings may contribute to the development of comprehensive metabolomics analyses with confounding factor-based adjustment and enhance the reliability and interpretability of future large-scale investigations.

Stability and Analytical Characterization of Voriconazole as Measured by Immunoassay.

Voriconazole is a broad-spectrum triazole antifungal agent recommended for invasive fungal diseases, including invasive aspergillosis. Therapeutic drug monitoring via voriconazole target trough concentration is important to ensure efficacy while preventing toxicity. Our aim was to determine the stability of voriconazole as adapted and measured by an immunoassay. Plasma from patient samples (n = 45) evaluated by a liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was compared against an ARK immunoassay method, adapted and optimized on the Abbott Alinity c analyzer. Stability of voriconazole and analytical performance of ARK immunoassay was assessed, including functional sensitivity, limit of blank (LoB), limit of detection (LoD), and limit of quantification (LoQ), linearity, and precision. ARK voriconazole immunoassay was highly correlated (Pearson R = 0.988) to the LC-MS/MS method, with an average bias of 0.09 mg/L (2%). CV at LoQ of 0.5 mg/L was 3.7% while the functional sensitivity was established at 0.05 mg/L. Overall imprecision with liquid quality control material obtained from ARK was 5.0%, 6.3%, and 5.9% at 1 mg/L, 5 mg/L, and 10 mg/L, respectively. Limit of blank and LoD were 0.02 mg/L and 0.05 mg/L, respectively. Voriconazole in lithium heparin plasma separator tube declines over time, with a decrease that is more evident near or above toxic concentrations. Voriconazole collected in gel separation tubes declines over time, possibly due to absorptive properties. Voriconazole measurements by immunoassay and LC-MS/MS demonstrated acceptable comparability with sufficient level of sensitivity and precision.

Five days serum glucose stability at room-temperature in centrifuged fast-clotting serum tubes and the comparability with glucose in heparin-plasma and plasma containing citrate-stabilizer

Glucose measurement plays a central role in the diagnosis of gestational diabetes mellitus (GDM). Because of earlier reports of overestimation of glucose in the widely used tubes containing granulated glycolysis inhibitor, the study assessed the performance of fast-clotting serum tubes as an alternative sample for the measurement of glucose. Glucose concentration in fast-clotting serum was compared to lithium-heparin plasma placed in an ice-water slurry after sample collection and glucose stability at room-temperature was studied. Blood samples from 30 volunteers were drawn in four different types of tubes (serum separator tubes, fast-clotting serum tubes, lithium-heparin tubes and sodium fluoride, EDTA and a citrate buffer (NaF–EDTA–citrate) tubes, all from Greiner Bio-One). Lithium-heparin tubes were placed in an ice-water slurry until centrifugation in accordance with international recommendations and centrifuged within 10 min. After centrifugation, glucose was measured in all tubes (timepoint T 0) and after 24, 48, 72, 96 and 120 h of storage at 20–22 °C. NaF–EDTA–citrate plasma showed significant overestimation of glucose concentration by 4.7% compared to lithium-heparin plasma; fast-clotting serum showed glucose concentrations clinically equivalent to lithium-heparin plasma. In fast-clotting serum tubes, mean bias between glucose concentration after 24, 48, 72, 96 and 120 h and T 0 was less than 2.4%. All individual differences compared to T 0 were less than 6.5%. The results fulfill the acceptance criteria for sample stability based on biological variation. Fast-clotting serum tubes can be an alternative for the measurement of glucose in diagnosis and management of GDM and diabetes mellitus, especially when prolonged transportation is necessary.

Evaluation of a New NT-proBNP Immunoassay on an Automated Core Laboratory System.

Heart failure remains a major cause of morbidity and mortality despite improvements in treatment. This study aimed to evaluate the Alere N-terminal pro B-type natriuretic peptide (NT-proBNP) immunoassay on the Abbott Alinity i platform. The analytical performance including precision, linearity, limit of quantitation (LOQ), carryover, dilution-recovery, and stability was evaluated. A method comparison between the Abbott Alere NT-proBNP assay and Roche Elecsys proBNP II assay was performed using 70 residual plasma samples. Total imprecision was 4.1%, 3.5%, and 2.3% for low (120.9 ng/L), medium (333.9 ng/L), and high (4767.4 ng/L) QC levels, respectively. The manufacturer's claimed LOQ of 8.3 ng/L was verified. Method comparison between the Alere NT-proBNP assay and the Elecsys proBNP II assay showed good agreement between assays with an R value of 0.998, a slope of 1.05 (95% CI, 1.03-1.06), and an intercept of 45.81 (95% CI, -46.6.84 to 138.22). The Bland-Altman plot showed an absolute bias of 250 ng/L or 6.02%. Subrange analysis (NT-proBNP <2000 ng/L) showed good agreement with an R value of 0.998, a slope of 1.04 (95% CI, 1.02-1.06), and an intercept of -4.83 (95% CI, -26.95 to 17.28), with a mean bias of 26 ng/L or 3.2%. The stability of NT-proBNP was also verified in lithium heparin plasma samples stored at 4°C over a 7-day period. Hemolysis and lipemia interference thresholds were verified, but icterus impacted NT-proBNP recovery by >20% at low analyte concentrations. The Alere NT-proBNP assay demonstrated acceptable analytical performance and very good clinical concordance with the Elecsys proBNP II assay.

A-187 The Effect of Ambient Temperature on Potassium During Hot Months: The Seasonal Pseudohypokalemia Delima!

Abstract Background Laboratory tests are vital tools for the clinicians and it is becoming more and more the most the decision maker for the management of patients. Blood samples are drawn from patients and transported to the laboratory for analysis; samples are exposed to various temperatures during transportation which could have an effect on test results. We studied the effect of seasonal change on the potassium results using lithium heparin plasma tubes. Method We compared the results collected from one day/month each from January 2022 to August 2022 from patients residing in Long-Term Care Facilities and were transported to the laboratory during which the samples were exposed to ambient temperature. A total of 16 086 specimens were collected using Lithium heparin plasma tubes up to 8/8/2022, sample on 8/15/22 were collected using serum gel separation tubes. Statistical analysis was done using Analyse-it. Results our results showed an increase in hypokalemia with the increase in ambient temperature, the highest incidence of hypokalemia was during the month of June to August which corresponds with the higher ambient temperature. There was an increase in hypoglycemia at the same time of the increase in hypokalemia. The percentage of samples with hypokalemia was normalized when serum (SST) tubes were used. Conclusion Seasonal pseudohypokalemia is phenomena that is seen when the samples are transported to the laboratory from different collection sites during the hot temperature. The increase in hypokalemia could be due to an increase in glucose metabolism and the cellular uptake of potassium or could be mediated by sodium-potassium-exchange-ATPase. Serum samples were less affected by the temperature change than lithium heparin plasma. It is very important to emphasis on the temperature during transporting samples to the laboratory to avoid seasonal pseudohypokalemia in the hot temperature season and hyperkalemia during the cold temperature season.

A-193 Effects of Delayed Centrifugation and Delayed Testing on the Stability of Comprehensive Metabolic Profile Analytes

Abstract Background The centralization of clinical laboratory testing has become increasingly common in recent years. While centralization allows for consolidation of resources, expanded test menus, procedural standardization, and improved efficiencies, central laboratories can face significant logistical challenges related to sample transport. In particular, problems may arise when samples are received from distant sites or if the courier services used to transport samples are infrequent or unreliable. Policies aimed to mitigate pre-analytical issues such as the time-to-centrifugation, the time-to-testing, and storage temperature, are best devised when driven by empiric data. Objective In this study, we provide stability studies for the Comprehensive Metabolic Panel (CMP) analytes in paired serum and lithium heparin (LiHep) plasma samples. Our findings not only complement preexisting literature data but also help guide the current sample acceptance criteria and policy for receiving satellite clinic samples in our laboratory. Methods Serum and LiHep plasma were collected from healthy volunteers in gel separator tubes. In one set of experiments, samples of both specimen types were all centrifuged within 30 min of collection and tested at pre-determined time intervals (2, 4, 6, 12, and 24 h post collection) using Roche Cobas 8000 system. In a second set of experiments, samples of both specimen types collected from another set of volunteers were kept at room temperature and only centrifuged prior to testing at pre-determined time intervals (2, 4, 6, 12, and 24 h post collection). Sample storage prior to testing was at room temperature. The percent recovery of each result was calculated relative to the first sample of the series. The CMP includes the following analytes: glucose, sodium, potassium, chloride, carbon dioxide, urea nitrogen, creatinine, calcium, total bilirubin, total protein, albumin, alkaline phosphatase, aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Results Glucose in promptly centrifuged (i.e., within 30 min of collection) LiHep plasma samples showed acceptable recovery (≥90%) when tested within 12 h of collection in LiHep gel separator tubes, whereas glucose stability in serum stored at room temperature exceeded 24 h. In contrast, delayed centrifugation beyond 3 h led to unacceptably low recoveries in both LiHep plasma and serum sample types. All other analytes included in the CMP were stable beyond 24 h irrespective of whether the sample type is LiHep plasma or serum, or even if the time-to-centrifugation was up to 24 h. Conclusions Based on the study, our laboratory has updated our policy to accept pre-centrifuged (i.e., within 30 min of collection) LiHep plasma from satellite clinics up to 8 h from blood collection, which is a 2-hour increase as compared to our prior cut-off acceptability. Given the location of our satellite clinics and unpredictability of sample transport, this increase represents a positive change in reducing outpatient sample rejections while ensuring reliable laboratory results.

A-285 Performance Evaluation of LIAISON® QuantiFERON®-TB Gold Plus Assay and Its Use in Long-Term Care Facilities

Abstract Background Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis with 7860 cases reported in 2021 in the United State and estimated 13 million people are living with Latent TB infection (LTBI); Early detection of TB infection is crucial to prevent the spread of the disease; there are two types of tests for TB and LTBI: Tuberculin Skin Test (TST) and Interferon-Gamma Release Assay (IGRA). Although TST has good sensitivity but false-negative reactions occur in certain population and the specificity of is decreased among persons with prior Bacillus Calmette-Guérin (BCG) vaccination, especially those vaccinated post-infancy and those with repeat vaccination. Similarly, persons living in areas where nontuberculous mycobacteria are common are at increased risk of having false-positive TST reactions. IGRA is blood-based laboratory test that measures responses to TB-specific peptide antigens in whole blood. Like the tuberculin skin test (TST), it is an indirect test for M. tuberculosis infection, but is more specific than TST and is unaffected by prior BCG vaccination and most environmental mycobacterial infections. Methods The LIAISON® QuantiFERON®-TB Gold Plus assay is an in vitro diagnostic test for the detection of interferon-γ (IFN-γ) in human lithium heparin plasma by chemiluminescence immunoassay (CLIA) using the LIAISON ® XL Analyzer. The clinical specificity and sensitivity were 96.9% and 84.4% respectively. Clinical studies have shown Positive Percent Agreement (PPA) of 97.4% and Negative Percent Agreement (NPA) of 98.6%. We evaluated the precision, reproducibility, and correlated patient results to our reference lab results. 452 samples collected from Long-Term Care facilities resident were run over 9 months. Statistical analyses were done using Analyse-it. Results The percentage agreement for precision, reproducibility, and accuracy were 100%. The correlation with the reference laboratory was 100% agreement. We found 14.8% of samples tested were positive, 83.2% were negative and 2.0% were indeterminate. Conclusion The LIAISON® QuantiFERON®-TB Gold Plus assay offers the benefit of a fully automated with high sensitivity and specificity. The faster turnaround will aid the physician in the diagnosing M. tuberculosis, eliminates the need for two-step testing, and is preferred in patients who received BCG vaccination. In addition, with the growing geriatric population, the availability of this test will give the physician the opportunity to follow the 2016 American Thoracic Society (ATS)/Infectious Disease Society of America (IDSA)/CDC clinical practice guidelines for using IGRAs in older patients.

A-023 Performance Evaluation of the Atellica IM High-Sensitivity Troponin I Assay on the Atellica CI 1900 Analyzer

Abstract Background The Atellica® CI 1900 Analyzer is an automated, high-throughput, integrated chemistry and immunoassay analyzer employing both Atellica CH and Atellica IM assays. This study was designed to evaluate the analytical performance of the Atellica IM High Sensitivity Troponin I (TnIH) assay* on the Atellica CI 1900 Analyzer*. Methods Precision and method comparison were used as performance indicators for the Atellica CI 1900 Analyzer. Precision studies were performed according to CLSI EP05-A3 and method comparison according to CLSI EP09-A3. Precision studies used a panel of four native and one contrived serum/lithium-heparin plasma samples. One aliquot of each sample pool was tested in duplicate in two runs per day &amp;gt;2 h apart on each analyzer for &amp;gt;20 days with two reagent lots on two systems. For the method comparison, individual native human lithium-heparin plasma samples were analyzed using the Atellica IM TnIH assay on both the Atellica IM and Atellica CI 1900 Analyzers. Detection capability studies including limit of blank (LoB), limit of detection (LoD), and 20-day functional sensitivity (LoQ) were performed according to CLSI EP17-A2 guidelines. Expected values of normal healthy individuals and hook effect were also verified on the Atellica CI 1900 Analyzer. Results Repeatability and within-lab %CVs ranged from 0.7% to 4.4% and 1.3% to 5.1%, respectively, at TnIH concentrations ranging from 13.73 to 23 197.12 ng/L. Method comparison between the Atellica IM TnIH assay on the Atellica CI 1900 Analyzer vs the Atellica IM Analyzer showed a regression slope of 1.00 and an intercept of 0.04 ng/L (n = 170). In detection capability studies, four lots of the Atellica IM TnIH assay on two Atellica CI 1900 analyzers showed a LoB of 0.35 ng/L and an LoD of 0.76 ng/L. LoQ, defined as the lowest amount of analyte in a sample at which within-lab %CV = 20%, was 1.10 ng/L; %CV was approximately 10% at a TNIH concentration of 2.57 ng/L. In addition, &amp;gt;50% of healthy individuals tested had TnIH values &amp;gt;LoD. The 99th percentile for the Atellica IM TnIH assay (45.20 ng/L) was verified on Atellica CI 1900 Analyzer and was consistent with the Atellica IM Analyzer. No interference from biotin was observed up to a concentration of 3500 ng/mL, and no hook effect was observed up to a concentration of 500 000 ng/L. Conclusion Evaluation of the Atellica IM TnIH assay using the Atellica CI 1900 Analyzer demonstrated reproducible assay precision, sensitive detection capabilities, and equivalent performance compared to the same assay on the Atellica IM Analyzer. This evaluation shows that the Atellica IM TnIH assay on Atellica CI 1900 Analyzer meets the definition of a true high-sensitivity troponin I assay as defined by the International Federation of Clinical Chemistry (IFCC) Task Force on Clinical Applications of Cardiac Biomarkers. *The products/features mentioned here are not commercially available in all countries. Their future availability cannot be guaranteed.