Lithium-heparin Plasma Samples Research Articles

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.

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.

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-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-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.

Evidence for the utility of cfDNA plasma concentrations to predict disease severity in COVID-19: a retrospective pilot study.

COVID-19 is a worldwide pandemic caused by the highly infective SARS-CoV-2. There is a need for biomarkers not only for overall prognosis but also for predicting the response to treatments and thus for improvements in the clinical management of patients with COVID-19. Circulating cell-free DNA (cfDNA) has emerged as a promising biomarker in the assessment of various pathological conditions. The aim of this retrospective and observational pilot study was to investigate the range of cfDNA plasma concentrations in hospitalized COVID-19 patients during the first wave of SARS-CoV-2 infection, to relate them to established inflammatory parameters as a correlative biomarker for disease severity, and to compare them with plasma levels in a healthy control group. Lithium-Heparin plasma samples were obtained from COVID-19 patients (n = 21) during hospitalization in the University Medical Centre of Mainz, Germany between March and June 2020, and the cfDNA concentrations were determined by quantitative PCR yielding amplicons of long interspersed nuclear elements (LINE-1). The cfDNA levels were compared with those of an uninfected control group (n = 19). Plasma cfDNA levels in COVID-19 patients ranged from 247.5 to 6,346.25 ng/ml and the mean concentration was 1,831 ± 1,388 ng/ml (± standard deviation), which was significantly different from the levels of the uninfected control group (p < 0.001). Regarding clinical complications, the highest correlation was found between cfDNA levels and the myositis (p = 0.049). In addition, cfDNA levels correlated with the "WHO clinical progression scale". D-Dimer and C-reactive protein (CRP) were the clinical laboratory parameters with the highest correlations with cfDNA levels. The results of this observational pilot study show a wide range in cfDNA plasma concentrations in patients with COVID-19 during the first wave of infection and confirm that cfDNA plasma concentrations serve as a predictive biomarker of disease severity in COVID-19.

Whole blood and plasma taurine reference intervals in adult Cavalier King Charles Spaniels and correlations between taurine concentration, diet and mitral valve disease.

To determine breed-specific reference intervals for whole blood (WB) and plasma taurine concentrations in adult, overtly healthy Cavalier King Charles Spaniels (CKCSs) and determine whether taurine concentrations differ across preclinical myxomatous mitral valve disease (MMVD) stages or between CKCSs eating diets that meet World Small Animal Veterinary Association (WSAVA) nutritional guidelines versus other diets. 200 privately owned CKCSs. Clinically healthy adult CKCSs were recruited prospectively. Diet and supplement history was collected. Dogs were staged by echocardiography using MMVD consensus guidelines. Taurine concentrations were measured in deproteinized lithium heparin WB and plasma samples with the postcolumn ninhydrin derivatization method on a dedicated amino acid analyzer. There were 12 stage A (6%), 150 stage B1 (75%), and 38 stage B2 (19%) CKCSs. Seventy-eight dogs (39%) were reported by their owners to be eating diets meeting WSAVA nutritional guidelines; 116 (58%) were not. Taurine concentrations in plasma (P = .444) and WB (P = .073) were not significantly different across MMVD stages or between CKCSs eating diets meeting WSAVA nutritional guidelines versus other diets (P = .345 and P = .527, respectively). Reference intervals for WB taurine (152 to 373 µM) and plasma taurine (51 to 217 µM) concentrations in CKCSs were generated. In CKCSs, taurine concentrations do not differ significantly based on preclinical MMVD stage, nor do they differ significantly based on consumption of a diet that does or does not meet WSAVA nutritional guidelines.

Analysis of diagnostic performance and factors causing nonspecific reactions in SARS-CoV-2 rapid antigen detection tests

IntroductionEarly diagnosis and appropriate infection control are important to prevent the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this study, we aimed to assess the diagnostic performance of SARS-CoV-2 rapid antigen detection (RAD) tests and the factors that cause nonspecific reactions. MethodsNasopharyngeal swab specimens (n = 100), sputum specimens (n = 10), and lithium-heparin plasma samples (n = 100) were collected. We evaluated Espline®SARS-CoV-2 (Espline) and SARS-CoV-2 Rapid Antigen Test that also known as STANDARD Q® (STANDARD Q), with reverse transcription-polymerase chain reaction (RT-PCR) and Lumipulse® Presto SARS-CoV-2 Ag as reference tests. In addition, we investigated the effects of inadequate pretreatment methods and five potential causes of nonspecific reactions. ResultsThe sensitivities of Espline and STANDARD Q were 60% and 57%, respectively, and their specificity was 100%. It was confirmed that the judgment line for the positive insufficiently mixed specimens was faint. A false-positive result was observed with STANDARD Q when sputum was used as a specimen to investigate judgment the effect of viscosity. ConclusionsEspline and STANDARD Q show good sensitivity for specimens with Ct values less than 25, but specimens collected within 9 days of symptom onset may still give false negatives. The test should be performed carefully, and the results should be judged comprehensively, taking into account clinical symptoms and patient background.

Effects of Various Anticoagulants on Biochemistry Analytes From Domestic Pigeons (Columba livia domestica).

The objective of this study was to compare the effects of anticoagulant and no anticoagulant on routine biochemical analytes in domestic pigeons (Columba livia domestica). Blood samples were obtained from 8 clinically healthy pigeons. The sample obtained from each bird was divided into 4 blood collection tubes containing either ethylenediaminetetraacetic acid (EDTA), lithium heparin, sodium citrate, or no anticoagulant. The concentrations of creatinine, uric acid, triglyceride, total cholesterol, glucose, phosphorus, calcium, magnesium, total protein, albumin, and iron, and the activities of alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), were measured in blood from each of the blood collection tubes. The values of the measured parameters, with the exception of iron, were significantly lower in the citrated plasma samples compared with the serum samples, even after correcting for dilution. In the lithium heparin plasma samples, significant decreases in albumin, triglyceride, calcium, total cholesterol, and ALP, and a significant increase in iron, were observed compared with the values in the serum samples. The concentrations of total protein, creatinine, glucose, total cholesterol, triglyceride, magnesium, calcium, and phosphorus, as well as the activities for AST and ALP, were significantly lower in the EDTA plasma samples compared with the serum samples. In conclusion, the anticoagulants had significant effects on most of the measured parameters compared with serum. The findings of the present study suggest that a lithium heparin sample is the most appropriate plasma sample for the measurement of blood biochemical parameters in the domestic pigeon.

Abstract 13442: Renin-Angiotensin Metabolite Profiling via LC-MS/MS Reveals Sex Dependent Differences Induced by High-Salt Diet in Dahl-S Rats

Background: Understanding how sex influences the pathophysiology of cardiovascular and renal disease may enhance precision medicine approaches that account for sex specific biologic differences in these diseases. Nevertheless, characterization of preclinical models often fail to account for the role of sex on important pathophysiologic mechanisms. The renin-angiotensin-aldosterone system (RAAS) plays a central role in the development and progression of cardiovascular and renal disease. In addition to the classic RAAS pathway, an alternative RAAS pathway produces angiotensins (e.g. Ang [1-7]) that can counteract classical RAAS hormones such as Angiotensin (Ang) II. We hypothesized that RAAS profiling in a high-salt fed Dahl-S rat model would reveal significant sex differences in both classic and alternative RAAS pathways. Methods/Results: Ten week-old male and female Dahl-S rats were fed either 0.2% salt normal chow (SS-NC), or 8% high-salt diet (SS-HS) for eight weeks (n=6-8/group). Equilibrium RAAS profiling via LC-MS/MS was performed in lithium heparin plasma samples. In response to high-salt diet, both male and female SS-HS rats had significant (p&lt;0.05) reductions vs. their respective SS-NC controls in plasma aldosterone (-93% in male SS-HS, -97% in female SS-HS), Ang II (-71% in male SS-HS, -41% in female SS-HS), Ang IV (-79% in male SS-HS, -54% in female SS-HS) as well as calculated plasma renin activity (-67% in male SS-HS, -42% in female SS-HS), although the magnitude of reduction was generally greater in males vs. females. Alternatively, only male SS-HS rats had significant (p&lt;0.05 vs. SS-NC) reductions in plasma Ang I (-63%), Ang III (-66%), as well RAAS metabolites of the alternative RAS axis, Ang [1-5] (-58%) and Ang [1-7] (-70%) vs. SS-NC. Comparing female vs. male SS-HS rats, females had significantly (p&lt;0.01 vs. male) increased levels of angiotensins of the classic RAS pathway, such as Ang I (113%), Ang II (104%), Ang III (150%) and Ang IV (265%) after high-salt diet. Conclusion: High-salt diet induces significant sex-dependent differences in both classic and alternative RAAS pathways of Dahl-S rats and may provide important insight into the sex-dependent differences of cardiovascular and renal injury seen in this model.

Total lab automation: sample stability of clinical chemistry parameters in an automated storage and retrieval module

Automated storage and retrieval modules (SRM), as part of total lab automation (TLA) systems, offer tremendous practical and economic benefits. In contrast to manual storage systems, SRMs indicate continuous motion of samples and may leave samples prone to temperature fluctuations. This study investigates analyte stability in serum and heparin plasma within an automated storage module. The stability of 28 common biochemistry analytes was investigated using 57 freshly obtained routine serum samples and 42 lithium-heparin plasma samples. Following baseline measurement, samples were stored at 2-8°C in the automated SRM of the Accelerator a3600 TLA and reanalyzed at fixed time points (2, 4, 8, 12, 24, 48 and 72h) on the Abbott Architect c16000 chemistry analyzer. The concentration at each time point was expressed as %-difference to the baseline value and mean results were compared to the criteria for desirable bias derived from the biological variation database. Nine of the analytes exceeded the bias criterion within 72h after initial measurement in either serum samples, plasma samples or both. Lithium-heparin plasma samples showed increasing values for phosphor, potassium and lactate dehydrogenase (LDH), which were only considered stable for respectively 24, 12 and 4h, glucose was considered stable for 8h. Electrolyte concentrations and LDH activity significantly increased in serum samples beyond 48h. Bicarbonate should not be performed as add-on test at all. The presented data indicate that the conditions within an SRM have no clinical impact on sample stability and allow stable measurement of routine analytes within 72h, comparable to manual storage facilities.

Evaluating the performance of an updated high-sensitivity troponin T assay with increased tolerance to biotin.

Biotin >20ng/mL may interfere with the Elecsys® Troponin T-high sensitive assay (cTnT-hs; Roche Diagnostics International Ltd). We evaluated the performance of an updated assay, cTnT-hs*, which was designed to reduce biotin interference. cTnT-hs* assay performance was assessed using up to two applications (18min/9min) on three analyzers (cobas e 411/cobas e 601/cobas e 801). Biotin interference was determined by measuring recovery in an 11-sample series dilution with biotin ranging from 0-3600ng/mL. Repeatability/reproducibility were evaluated in five serum sample pools (n=75 each). Method comparisons tested: cTnT-hs* vs. cTnT-hs (18min/cobas e 601); cTnT-hs* assay 18 vs. 9min (cobas e 601); cTnT-hs* (18min) on cobas e 601 vs. cobas e 411 and cobas e 601 vs. cobas e 801. Concordance at the 99th percentile decision limit between cTnT-hs* and cTnT-hs (9min/cobas e 601) was calculated using 300 lithium-heparin plasma samples and a 14ng/L assay cutoff. cTnT-hs* assay (18min/cobas e 601) recovery was≥96% for biotin≤1250ng/mL. Across all applications/analyzers, coefficients of variation for repeatability/reproducibility with the cTnT-hs* assay were <5% in most serum sample pools (mean cardiac troponin T: 8.528-9484ng/L). High correlation (Pearson's r=1.000) was demonstrated for all method comparisons. Concordance at the 99th percentile decision limit was high between the cTnT-hs* and cTnT-hs assays. The updated cTnT-hs* assay may provide greater tolerance to biotin interference, and shows good analytical and clinical agreement/concordance with the previous cTnT-hs assay.

Cardiac troponin I in SARS-CoV-2-patients: The additional prognostic value of serial monitoring

BackgroundMajor cardiac complications have been described in SARS-CoV-2 patients. The study of cardiac troponin’ kinetic release is the recommended approach to differentiate acute from chronic injury, in order to clinically manage different cardiac diseases. AimTo investigate whether serial measurements of high sensitivity troponin I (hs-cTnI) might provide additional information in SARS-CoV-2 patients’s clinical management. Methods113 consecutive patients suffering from microbiology proven SARS-CoV2-infection have been studied. Hs-cTnI has been measured in lithium-heparin plasma samples using STAT High Sensitive Troponin I (Architect i2000, Abbott Diagnostics), being 99th percentiles 16 and 34 ng/L for females and males respectively. ResultsIn 69 out of 113 patients hs-cTnI has been measured, showing in 31 (45%) values higher than 99th percentiles in at least one occasion. In 50 patients (72%) a kinetic evaluation (at least 2 measurements during 24 h) has been carried out. Patients were subdivided into five groups: 1 (n = 44) and 2 (n = 19) no measurement of hs-cTnI or no monitoring respectively; 3 (n = 15) no significant variations during monitoring; 4 (n = 8) and 5 (n = 27) significant variations with values persistently below or sometimes higher than 99th percentiles, respectively. Group 5 patients had a longer hospital stay (median 37 days, p = 0.0001), a more aggressive disease (6 out of 27, 22%, died), more often need admission to ICU (n = 25, 92.6%, p < 0.0001), and show one or more peak values, sometime preceded by severe hypoxia. ConclusionsIn SARS-CoV-2 patients, hs-cTnI serial monitoring may provide additional data to stratify risk, establish prognosis and gaining epidemiological insight on cardiac involvement in this pandemic disease.

Establishing the 99th percentile of a novel assay for high-sensitivity troponin I in a healthy blood donor population.

The recommended cut-off of cardiac troponin (cTn) for the diagnosis of acute myocardial infarction (AMI) is the 99th percentile in a healthy reference population. We aimed to determine the 99th percentile of the novel ADVIA Centaur® High Sensitivity Troponin I assay (Siemens Healthcare Diagnostics) in fresh lithium heparin plasma samples from healthy blood donors. A total of 1000 apparently healthy blood donors were included. High-sensitivity (hs) cTnI, hs-cTnT, creatinine and N-terminal pro b-type natriuretic peptide (NT-proBNP) were measured in fresh lithium heparin plasma samples, and glycated hemoglobin (HbA1c) was measured in ethylenediaminetetraacetic acid (EDTA)-blood. The 99th percentile was estimated for the whole population, as well as for males and females separately. For the total population the 99th percentile of ADVIA Centaur® High Sensitivity Troponin I was 96 (65-149) ng/L. The estimated value differed significantly from results published by others and was highly dependent on which values were considered statistical outliers. The estimated 99th percentile for hs-cTnI in the population studied differed significantly from previously published results. There is a need for further specifications regarding how subjects used for estimating the 99th percentile of cTns in healthy populations should be recruited and how outlier values should be identified, as this can highly influence the diagnostic cut-off applied for AMI.

Analytical evaluation of Radiometer ABL90 FLEX PLUS enzymatic creatinine assay

Background: The diagnosis of kidney disease strongly relies on accurate and reproducible measurements of creatinine, even when performed with point of care testing (POCT) devices. Therefore, this study aimed at performing a comprehensive evaluation of the analytical performance of a creatinine enzymatic assay on the Radiometer ABL90 FLEX PLUS. Methods: This analytical evaluation encompassed the assessment of intra-assay, inter-assay and total imprecision, along with linearity on routine lithium-heparin plasma samples. Method comparison was also carried out using results generated with Radiometer ABL90 FLEX PLUS in heparinized whole blood and those obtained in paired heparinized plasma with a reference enzymatic creatinine assay and a Jaffe method, both assayed on Roche Cobas c702. Results: The intra-assay imprecision of Radiometer ABL90 FLEX PLUS creatinine enzymatic assay was between 0.33–1.26%, the inter-assay imprecision between 0.64–1.78%, thus yielding a total imprecision of 0.79–1.99%. The linearity of the assay was excellent (r=1.000; P Conclusions: The results of this analytical evaluation confirm that Radiometer ABL90 FLEX PLUS creatinine enzymatic assay is at least as suitable as a conventional clinical chemistry enzymatic technique for routine and urgent diagnosis of kidney diseases.

Analytical performance evaluation of the Elecsys® Troponin T Gen 5 STAT assay

BackgroundWe report the analytical performance of the Elecsys® Troponin T Gen 5 STAT (TnT Gen 5 STAT; Roche Diagnostics) assay. MethodsMeasuring limits/ranges were determined in lithium-heparin plasma samples per Clinical and Laboratory Standards Institute (CLSI) EP17-A2. Precision was evaluated per CLSI EP05-A2 using lithium-heparin plasma/quality control samples on cobas e 411/cobas e 601 analyzers; two duplicated runs per day for 21 days (n = 84). Cross-reactivity with other troponin forms and interference from endogenous substances/drugs was tested; recovery criterion for no cross-reactivity was within ±10%. ResultsCoefficients of variation (CV) for repeatability/intermediate precision were 0.7–5.6%/1.4–10.3% (cobas e 411; mean cardiac troponin T [cTnT]: 7.3–9341 ng/L) and 0.7–3.0%/1.5–6.4% (cobas e 601; mean cTnT: 7.4–9455 ng/L). There was no cross-reactivity with skeletal muscle troponin T (≤ 10,000 ng/L), skeletal muscle troponin I (≤ 100,000 ng/L), cardiac troponin I (≤ 10,000 ng/L), or human troponin C (≤ 80,000 ng/L). No interference was observed with biotin (≤ 20 ng/mL) or 34 drugs. ConclusionThe TnT Gen 5 STAT assay demonstrated a CV of <10% at the 99th percentile upper reference limit, meeting precision requirements (Fourth Universal Definition of Myocardial Infarction) for high-sensitivity troponin assays.

Bone turnover markers are differentially affected by pre-analytical handling.

Bone turnover markers are often shipped to central laboratories for analysis, which require knowledge of the stability of the markers of interest in different sample materials. The aim of the current study was to evaluate how time before separation of blood samples and time between separation and analysis affect the stability of four bone turnover markers in serum and plasma samples. Serum, EDTA, and Lithium heparin (LiHep) plasma samples from seven osteoporosis patients and three healthy controls were collected and stored at room temperature for up to 72h before separation and analysis. After separation, samples were stored at room temperature for up to 72h and re-analyzed. The bone turnover markers N-terminal pro-collagen type 1 extension pro-peptide (P1NP), bone-specific alkaline phosphatase (BAP), C-terminal teleopeptide cross links of collagen type 1 (CTX), and osteocalcin (OC) were analyzed using the automated iSYS IDS platform. P1NP and BAP were stable in both plasma and serum for 72h before centrifugation. CTX levels were higher in EDTA plasma at all time points compared to LiHep plasma and serum. The use of EDTA plasma prolonged the stability of CTX as compared to LiHep plasma and serum. Osteocalcin showed high tendency to degrade in all sample types and concentrations were significantly lower after 24h of storage. For the bone turnover markers P1NP and BAP, the use of both plasma and serum is recommended. Samples for CTX analysis should be taken as EDTA plasma. Samples for osteocalcin analysis can be taken in either type of plasma or serum, but should be analyzed within 3h or preserved at - 18°C.

Validation of the analytical performance of Lumipulse G BRAHMS procalcitonin immunoassay on low sample volume

Background: The measurement of procalcitonin (PCT) is currently considered a cornerstone in the diagnostic approach of patients with severe bacterial infections and for monitoring antimicrobial therapy. However, since low volume samples represent a challenge for PCT measurement, this study was aimed to investigate the analytical recovery of Lumipulse G BRAHMS PCT immunoassay using serially diluted lithium-heparin plasma samples. Methods: Fifteen fresh lithium-heparin plasma samples were arbitrarily selected to cover clinically significant measuring ranges of PCT values (low PCT, 0.034–0.085 ng/mL; medium PCT, 0.092–0.638 ng/mL; high PCT, 2.022–9.187 ng/mL). The samples were diluted with Lumipulse sample diluent, to obtain 5 progressive dilutions (1:2; 1:5; 1:10; 1:20 and 1:32). The original samples and each serial dilution were then measured with Lumipulse G BRAHMS PCT immunoassay, and PCT data obtained on dilutions were compared to their theoretical values. An additional measurement of original plasma samples was performed with automatic 1:10 sample dilution set in the analyzer. Results: The correlation between measured and theoretical PCT values was always excellent (i.e., r=0.999–1.000), whilst slopes and intercepts were also satisfactory. The mean recovery between theoretical and measured PCT values was ±14%, ±7% and ±1% for low, mean and high sets of samples, respectively. The mean recovery of 1:10 diluted specimens was comprised within ±20% with manual dilution and ±21% with automatic dilution for low PCT values, within ±5% with manual dilution and ±7% with automatic dilution for medium PCT values, within ±2% with manual dilution and ±1% with automatic dilution for high PCT values. Conclusions: The results of our study suggest that measuring PCT with Lumipulse G BRAHMS immunoassay using diluted (e.g., 1:10) plasma samples is a viable option to obtained accurate data and consume a much lower volume of plasma.

Relationship between alkaline phosphatase and impaired coronary flow in patients with ST-segment elevated myocardial infarction.

ObjectiveRecent studies have shown that alkaline phosphatase (ALP) might play a negative role in clinical outcomes of patients with peripheral and coronary artery disease. This study aimed to investigate the relationship between serum ALP levels and coronary thrombolysis in myocardial infarction (TIMI) frame counts in patients with ST-segment elevated myocardial infarction undergoing primary percutaneous coronary intervention (PCI).MethodsA total of 198 patients were enrolled in the current study. Serum ALP levels were measured in lithium-heparin plasma samples via a standardized, colorimetric enzyme assay. Coronary TIMI flow was evaluated by counting the number of cine frames that were required for contrast to reach a standardized distal coronary landmark in the culprit vessel.ResultsThe Spearman correlation coefficient test showed strong positive relationships between coronary TIMI frame counts after primary PCI and serum ALP levels on admittance for the left anterior descending, circumflex, and right coronary arteries (r = 0.774, r = 0.831, and r = 0.730, respectively).ConclusionElevated serum ALP levels appear to be a predictor of impaired coronary TIMI frame count in patients suffering from ST-segment elevated myocardial infarction.

Assessing matrix, interferences and comparability between the Abbott Diagnostics and the Beckman Coulter high-sensitivity cardiac troponin I assays.

Analytical evaluation of high-sensitivity cardiac troponin (hs-cTn) assays, with particular attention to imprecision, interferences and matrix effects, at normal cTn concentrations, is of utmost importance as many different clinical algorithms use concentration cutoffs <10 ng/L for decision-making. The objective for the present analytical study was to compare the new Beckman Coulter hs-cTnI assay (Access hsTnI) to Abbott's hs-cTnI assay in different matrices and for different interferences, with a focus on concentrations <10 ng/L. The limit of blank (LoB) and the limit of detection (LoD) were determined in different matrices for the Beckman hs-cTnI assay. Passing-Bablok regression and difference plots were determined for 200 matched lithium heparin and EDTA plasma samples for the Beckman assay and 200 lithium heparin samples for the Abbott assay. Both EDTA and heparin plasma samples were also evaluated for stability under refrigerated conditions, for endogenous alkaline phosphatase interference and for hemolysis and icterus. The Beckman hs-cTnI assay LoB was 0.5 ng/L with the following range of LoDs=0.8-1.2 ng/L, with EDTA plasma yielding lower concentrations as compared to lithium heparin plasma (mean difference=-14.9%; 95% CI=-16.9 to 12.9). Below 10 ng/L, lithium heparin cTnI results from the Beckman assay were on average 1.1 ng/L (95% CI=0.7 to 1.5) higher than the Abbott results, with no difference between the methods when using EDTA plasma (mean difference =-0.1 ng/L; 95% CI=-0.3 to 0.2). Low cTnI concentrations were less effected by interferences in EDTA plasma. The Access hsTnI method can reliably detect normal cTnI concentrations with both lithium heparin and EDTA plasma being suitable matrices.