Journal of Applied Laboratory Medicine最新文献

Background: High-sensitivity cardiac troponin (hs-cTn) assays are recommended for the diagnosis of acute myocardial infarction. Here, we characterize the analytical performance of a next-generation hs-cTn assay, Elecsys® Troponin T hs Gen 6 (Roche Diagnostics International).

Methods: Surplus lithium-heparin plasma or serum samples from patients or healthy volunteers were run on Cobas® e 801, e 402, and Pro analyzers. Limits of blank (LoB), limits of detection (LoD), and limits of quantitation (LoQ) were determined according to CLSI EP17-A2, with target values of 1.0 and 1.5 ng/L for LoB/LoD and 3.0 ng/L (10% CV) and 1.5 ng/L (20% CV) for LoQ, respectively. Precision was measured, per CLSI EP17-A2, using 3 QC samples (approximately 4, 30, and 220 ng/L), 12 native samples, and 3 reagent lots. Linearity, per CLSI EP06-Ed2, was determined by diluting samples with cardiac troponin T (cTnT) concentration above the measuring range with a low/blank sample. Interference (per Glick) with endogenous and assay components at 5 cTnT concentrations was assessed.

Results: Measured values for LoB, LoD, and LoQ at 10% and 20% CV were 0.1 to 0.7 ng/L, 0.3 to 1.4 ng/L, 1.0 to 2.9 ng/L, and 0.4 to 1.2 ng/L, respectively. Repeatability CVs were 1.0 to 5.8% for mean cTnT concentrations of 2.6 to 9230 ng/L in lithium-heparin plasma. High precision was shown across lots, and linearity was observed across the measuring range (1.5 to 9500 ng/L, all Pearson's r = 1.00). No interferences were observed, specified up to ≤1000 mg/dL hemoglobin, ≤50 mg/dL [≤855 µmol/L] icterus/bilirubin, and ≤1200 ng/mL biotin.

Conclusions: The analytical performance characterization of the assay demonstrated high sensitivity, high precision at the low end and across the measuring range, and resistance to interference.

Background: Accurate potassium measurements are clinically important because life-threatening arrhythmias can occur at high or low potassium levels. Even mild dyskalemia is associated with adverse clinical outcomes. However, preanalytical factors and varying specimen types-serum, plasma, and whole blood-pose challenges in accurately measuring potassium, establishing reference intervals (RIs), and interpreting the results.

Methods: Adult RIs for potassium were acquired from 60 laboratory directories. The distribution of plasma potassium values at a cancer center and effects of applying different RIs were evaluated.

Results: Surveyed laboratories have 14 different RIs for serum potassium and, usually, the same RI for serum and plasma. Only 4 laboratories had different serum and plasma RIs. Applying common serum RIs to plasma measurements markedly affected the proportions of patient results outside the RI.

Discussion: Although potassium measurements are relatively well standardized, laboratory RIs for potassium vary considerably. Most laboratories use the same RI for serum and plasma potassium, although serum and plasma measurements usually differ by 0.2-0.4 mmol/L, exceeding acceptable limits for bias. Consequently, serum-derived RIs are suboptimal RIs for plasma. Testing of plasma specimens is common in acute care settings, but most laboratory RIs and clinical guidelines are based on serum measurements. Outcome studies show that there is a narrow optimal range for potassium levels and that outcomes improve with careful management of potassium levels. Separate RIs and clinical guideline values for plasma and serum potassium offer better assessment of potassium levels.

Background: Ubiquitin C-terminal hydrolase-L1 (UCH-L1) and glial fibrillary acidic protein (GFAP) have been evaluated as an alternative to S100 calcium binding protein B (S100B), which is mentioned in the Scandinavian guideline for managing mild traumatic brain injury (mTBI). Preanalytical, analytical and diagnostic performance of GFAP/UCH-L1 must be assessed before clinical use.

Methods: GFAP/UCH-L1 were quantified using the TBI assay on Abbott Alinity. Precision was estimated using internal quality controls, and matrix effects were evaluated using serum and plasma from 30 outpatients. Repeatability and stability at different conditions (25, 4, -20, and -80°C) were evaluated on serum and plasma. GFAP and UCH-L1 serum levels in 30 healthy individuals were determined and compared to S100B levels.

Results: Inter-instrumental precision was ≤4.2% for both biomarkers. Random outliers were observed for UCH-L1 in plasma, where 5 measurements deviated >25%. Acceptable storage stability was found for GFAP and UCH-L1. All healthy individuals had GFAP values within the manufacturer's reference interval (6.6 to 70.9 ng/L) and two exceeded the upper limit for UCH-L1 (44.7 to 226.8 ng/L). Four healthy individuals (13%) had GFAP results above cutoff without S100B exceeding its cutoff, while one individual had values of S100B above cutoff but GFAP below cutoff.

Conclusions: The analytical precision and storage conditions of GFAP/UCH-L1 were satisfactory. Serum and plasma can be used for measurement of GFAP, whereas UCH-L1 measurement in plasma is not advised until further evaluations are conducted. The manufacturer's upper reference limits may not be suitable for our population. Thorough research on cutoff values is necessary.

Background: Analytical performance specifications for laboratory tests are essential components of quality assurance for clinical laboratories. A widely adopted performance criterion is total allowable error (TEa), which includes contributions from both bias and imprecision, which may contribute to test inaccuracies. However, the relationship of TEa to test result misclassification, a clinically relevant quality measure, is unclear.

Methods: Hypothetical clinical laboratory test results for 4 test models were generated and subjected to proportional bias and imprecision. Test misclassification (TM) as a function of bias and imprecision was determined using pre-defined cutpoint(s). Simulation analyses were then performed on 14 chemistry analytes using 3 data sets from patient results reported at the National Institutes of Health (NIH).

Results: We observed a complex and nonlinear relationship between bias and imprecision, and their impact on TM was not additive as may have been expected with TEa. TM scores were influenced by population distribution, the location of cutpoints, and the fraction of abnormal test values at baseline. Stringent TEa requirements did not correspond to low TM scores. On the contrary, TM scores for electrolytes were among the highest. Instead, TM scores closely correlated with the ratio of TEa to the width of the population distribution.

Conclusion: TM has the advantage of correctly accounting for the differential effects of bias and imprecision. Compared to TEa, it provides a more accessible metric for evaluating performance and the clinical impact of errors.

Since 2016, the Asia-Pacific Working Group (APWG) has supported the Association for Diagnostics & Laboratory Medicine's (ADLM) Global Lab Quality Initiative (GLQI) by enhancing laboratory medicine education and training in developing countries. The group has delivered programs in 10 countries across the Asia-Pacific region. To better understand the regional landscape and country-specific needs, the APWG conducted a comprehensive needs assessment through an APWG survey and virtual interviews. The findings demonstrated the complexity of the Asia-Pacific region, while also revealing a common interest in enhancing laboratory quality. Common challenges identified include limited resources, financial constraints, outdated technology, and staff shortages. The needs assessment analysis will guide the APWG to carry out further programs to enhance laboratory quality education for laboratorians across diverse geographical regions.

The Association for Diagnostics & Laboratory Medicine (ADLM) aims to improve health by providing education to laboratory scientists worldwide. Different regions of the world face unique challenges shaped by their national and regional contexts. However, the needs of clinical laboratories worldwide remain largely understudied. To address this gap, we conducted a comprehensive needs assessment survey among laboratory professionals in the Latin American region. The survey was distributed to over 2708 individuals across Latin American countries and yielded 148 responses. Most respondents were from urban areas (74%) and worked in private hospital laboratories (45%), with microbiology (25%) and chemistry (23%) identified as the most common specialties. Key findings include continuing education as the top challenge, identified by 59% of respondents, with a predominant preference for virtual learning formats (83%), though not exclusively; 50% also identified a preference for in-person learning. Other challenges, such as staff shortages, lack of equipment and funding, were selected by 30% to 36% of respondents, whereas regulatory oversight and quality management were less frequently identified as priorities. To contextualize the survey findings, we conducted interviews with laboratory professionals in the region. Common themes included resource and technology constraints, uneven implementation of quality standards, and the need for collaboration between government and professional organizations to bridge gaps in practice. This assessment highlights the need for targeted educational interventions to address the distinct challenges faced by Latin American laboratories. Addressing these gaps in continued education, fostering collaboration, and engaging stakeholders in the region offer a roadmap to strengthening laboratory services and health outcomes.