Clinical chemistry and laboratory medicine最新文献

Objectives: Isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC MS/MS)-based candidate reference measurement procedures (RMPs) for the quantification of 24,25(OH)₂D2 and 24,25(OH)₂D3 in human serum and plasma are presented.

Methods: Quantitative nuclear magnetic resonance (qNMR) spectroscopic methodology was utilized to assign absolute content (g/g) and SI-traceability to reference materials used as primary calibrators. For liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis a two-dimensional heart cut LC approach, in combination with a supported liquid extraction protocol, was established to mitigate matrix effects and prevent co-elution of interferences. Selectivity was determined by spiking the internal standards and similar compounds, in human serum. A post-column infusion experiment and comparison of standard line slopes was performed to evaluate matrix effects. Precision and accuracy were assessed via a multi-day validation experiment, utilizing certified secondary reference materials from the National Institute of Standards and Technology (NIST). Measurement uncertainty (MU) was evaluated per the Guide to the Expression of Uncertainty in Measurement (GUM). To demonstrate equivalence with the JCTLM-listed RMP, certified secondary reference materials were utilized. Additionally, a method comparison study was conducted with the 24,25(OH)₂D3 method used by the CDC Vitamin D Reference Laboratory.

Results: The RMP allowed quantification of 24,25(OH)2D2 and 24,25(OH)2D3 within the range of 0.150-18.0 ng/mL (0.350-42.0 nmol/L 24,25(OH)₂D2 and 0.360-43.2 nmol/L 24,25(OH)₂D3) without interference from structurally-related compounds and no evidence of matrix effects. Intermediate precision was ≤2.3 % for 24,25(OH)₂D2 and ≤2.9 % for 24,25(OH)₂D3; repeatability was ≤1.4 % for 24,25(OH)₂D2 and ≤2.1 % for 24,25(OH)₂D3, across all concentration levels. The relative mean bias was -4.5 to 2.9 % for 24,25(OH)₂D2, and -3.7 to 3.6 % for 24,25(OH)₂D3. Expanded MU for reference value assignment for 24,25(OH)₂D2 and 24,25(OH)₂D3 for reference value assignment was ≤2.5 %, regardless of concentration level and sample type. Passing-Bablok regression revealed strong agreement between the 24,25(OH)₂D3 results from the candidate RMPs and those provided by the CDC Vitamin D Reference Laboratory.

Conclusions: These RMPs permit accurate and reproducible determination of 24,25(OH)₂D2 and 24,25(OH)₂D3. Implementation of these methods supports routine assay standardization and patient sample measurement with confirmed traceability.

Objectives: We examined the magnitude of transcription errors in lipid variables in the VIPVIZA study and assessed whether education among the research personnel reduced the error frequency at follow-up. We also examined how the errors affected the SCORE2 risk prediction algorithm for cardiovascular disease, which includes lipid parameters, as this could lead to an incorrect treatment decision.

Methods: The VIPVIZA study includes assessment of lipid parameters, where results for total cholesterol, triglycerides, HDL cholesterol, and calculated LDL cholesterol are transcribed into the research database by research nurses. Transcription errors were identified by recalculating LDL cholesterol, and a difference>0.15 indicated a transcription error in any of the four lipid parameters. To assess the presence of risk category misclassification, we compared the individual's SCORE2 risk category based on incorrect lipid levels to the SCORE2 categories based on the correct lipid levels.

Results: The transcription error frequency was 0.55 % in the 2019 VIPVIZA research database and halved after the educational intervention to 0.25 % in 2023. Of the 39 individuals who had a transcription error in total or HDL cholesterol (with the possibility of affecting the SCORE2 risk category based on non-HDL cholesterol), six individuals (15 %) received an incorrect risk category due to the error.

Conclusions: Transcription errors persist despite digitalisation improvements. It is essential to minimise transcriptions in fields outside the laboratory environment, as we observed that critical decisions also rely on accurate information such as the SCORE2-risk algorithm, which is dependent on lab results but not necessarily reported by the laboratory.

Objectives: Detailed technical instructions have been made for harmonization of the prothrombin time (PT) test using the manual tilt tube technique (MTT). The MTT has been proposed as the reference measurement procedure for PT and international normalized ratio (INR). An external quality assessment (EQA) scheme has been developed specifically for calibration laboratories performing the harmonized MTT. Here we report the results of the first 10 surveys of this new EQA scheme and investigate whether there is improvement in performance over time and in comparison with previous studies.

Methods: Four deep-frozen plasma samples with different PT levels were dispatched to 4 European laboratories. PT's were determined by eight operators. All operators used the same PT reagent (recombinant human). Various measures of PT variation were defined, i.e. within-operator, within-survey, within-run, between-operator, and between-survey coefficient of variation. Between-operator variation (CV_S) was calculated from the each operator's mean PT.

Results: The median within-operator variation of all operators varied from 1.3 to 2.3 %. Some operators improved their performance, others did not. Between-operator CV (CV_S) ranged from 1.0 to 2.2 %. Overall, the between-operator and within-operator variation using the harmonized MTT was lower than in a previously published multicentre calibration study. Overall, the within-operator variation was low and did not change significantly over time.

Conclusions: within-operator and between-operator variation of the PT measured with the harmonized MTT were low when compared with previous studies. The results suggest that the average within-operator variation of the eight operators in this study is as low as possible.

Objectives: The knowledge of the measurement uncertainty (MU) of a diagnostic laboratory test is essential to keep the reliability of laboratory results under control, is requested by regulatory bodies, and for the clinician to be aware of the grey zone of variability around the reported values. The calculation of the percent allowable total error (%aTE) defines the levels of acceptable and optimal MU for each measurand. The CD34+ hemopoietic precursor cell level in blood, as a flow cytometric measurand, still lacks reliable MU and %aTE indicators.

Methods: %aTE of the absolute count of CD34+ cells in stabilized peripheral blood has been evaluated using a UKNEQAS database of 69,294 valid results entries from the Stem Cell Enumeration EQA/PT Programme over the last 20 years. The state-of-the-art (SOTA) desirable performance achievable by 80 % of participants and the optimal performance by the best laboratories were calculated at four levels of absolute CD34+ cell counts, from 0 to 10 to >50 cells/μL.

Results: Double platform users displayed worse %aTE as compared to single platform users in both periods, with a general trend to improvement with time. Single platform users in the 2014-2024 decade performed best, with a flat %aTE trend over the years. The SOTA-based %aTE were calculated for each method and every decision-making cell level, showing relatively narrow ranges.

Conclusions: Our EQA/PT study with stabilized peripheral blood CD34+ cell suspensions reliably estimated the %aTE of the absolute CD34+ cell count, mostly related to the purely analytical variability and devoid of the preanalytical interferences caused by the decay of fresh samples.

Objectives: Patient risk management is an essential subject for clinical laboratory which is now central in main international laboratory quality standards (e.g., ISO 15989:2022; ISO 22367:2020 and CLSI EP23^2nd). Risk analysis is a necessary part of risk management which requires categorizing the severity of patient harm from a laboratory failure. However, this subjective task is not currently the subject of any recommendation and little literature about this topic. To remedy that, we conducted an international survey of medical biology professionals, asking them to rate a panel of 20 analytes the harm potentially induced by an erroneous reported result.

Methods: The survey was published by Bio-Rad^® to their customers base and the public with a dedicated webpage. The survey proposes to assign for the submitted analytes the amount of harm among five pre-defined categories of harm: negligible, minor, serious, critical, and catastrophic. Participants were also asked to specify their demographic characteristics.

Results: The questionnaires of 267 respondents coming from 43 countries were analyzed to allocate for each analyte a specific harm category. We highlight that almost all parameters (19/20) were categorized with at least a serious harm category and that none were associated with the negligible category.

Conclusions: This study constitutes the first international attempt to investigate how the laboratory community thinks about patient harm from an erroneous reported result. These results provide support to document the laboratory risk management policy which must now be centered on patient risk.

Malignant effusions, pleural effusion or ascites, represent a common problem in cancer patients. Pleural effusion in a cancer patient may be caused also by non-neoplastic conditions, and the diagnosis of malignant pleural effusion is established by the demonstration of tumor cells in pleural fluid. Microscopical detection of tumor cells in pleural fluid often fails, and there is an unmet medical need for more sensitive methods. New approaches, including isolation using magnetic beads coated with monoclonal antibodies targeting antigens expressed on tumor cells not only increase the diagnostic sensitivity, but also provide material for the analysis of predictive biomarkers. The advent of new technologies illustrates the incremental role of laboratory medicine in the management of patients with malignant effusions.