Clinical chemistry and laboratory medicine最新文献

Objectives: The present multicenter study was designed to evaluate the analytical performance and the 99th percentile value of the reference healthy population i.e., 99th percentile upper reference limit of the MAGLUMI^® CLIA high-sensitivity cardiac troponin I (hs-cTnI) method.

Methods: Analytical performances and the 99th percentile URL value of the chemi-luminescent-immuno-assay (CLIA) method were evaluated using validated and standardized experimental protocols. Two cohorts including healthy adult individuals were enrolled. The first one included 989 blood donor volunteers (489 women and 500 men) aged 18-70 years (mean age 43 years, interquartile range 31-54 years). The second population included 47 healthy individuals (31 women and 16 men, mean age 78 years, interquartile range 73-81 years) aged≥71 years.

Results: The distributions of hs-cTnI levels in both sexes are highly right-skewed, and men show significantly (p=0.0028) higher biomarker values than women. Moreover, in both sexes the hs-cTnI levels progressively increase after the 55 years. In the multivariate analysis (n=958), hs-cTnI was found to be significantly associated to NT-proBNP (p<0.0001), sex (p<0.0001) and BMI (p=0.0424). The 99th percentile URL values, calculated using the bootstrap method in the total reference heathy population (age≥18 years), were: Females (n=521): 5.93 ng/L (CI 95 % 5.29-8.48), Males (n=516): 9.79 ng/L (CI 95 % 6.37-17.41 ng/L), Total Population (n=1,037): 7.18 ng/L (CI 6.08-12.20 ng/L).

Conclusions: The MAGLUMI CLIA method met all the criteria for an hs-cTnI assay recommended by international guidelines. The hs-cTnI values measured with the CLIA method are higher in men compared to women at the same age, and also progressively increase after the age>55 years.

External quality assessment (EQA) cycles are the smallest complete units within EQA programs that laboratories can use to obtain external assessments of their performance. In each cycle, several samples are distributed to the laboratories registered for participation, and ideally, EQA programs not only cover the examination procedures but also the pre- and post-examination procedures. The properties and concentration range of measurands in individual samples are selected with regard to the intended challenge for the participants so that each sample fulfils its purpose. This aims to ensure the most significant possible information gain in every cycle using the lowest possible number of EQA samples and thus, under economically optimal conditions. Participants examine samples and the results are reported to the EQA provider, who compares them with the target values for individual measurands in every sample. The EQA provider assesses the laboratory performance, and finally communicates the assessment results to the participant. The participants evaluate the outcomes of the assessment of their examination results and can draw conclusions in the case of both failing and passing and, if necessary, define improvement measures. After completion, each cycle is evaluated by the provider so that limitations and weaknesses of the EQA program can be identified and appropriate measures taken, or to confirm its continued suitability and appropriateness.

The EN ISO 15189:2022 standard, titled "Medical laboratories - Requirements for quality and competence," is a significant update to the regulations for medical laboratories. The revised standard was published on December 6, 2022, replacing both EN ISO 15189:2012 and EN ISO 22870:2016. Key objectives of the revision include: 1. Alignment with ISO/IEC 17025:2017, 2. Removal of unintended prescription, 3. Focus on patient interest and safety, 4. Minimization of new requirements, and 5. Improved clarity of text. Dedicating to harmonizing accreditation processes across Europe the EFLM Committee on Accreditation and ISO/CEN standards (C: A/ISO) has produced this guidance document to assist the laboratory medicine community in understanding and implementing the criteria of the EN ISO 15189 revision. Two main objectives of the guidance in educating both laboratories and accreditation bodies with their assessors as well as other stakeholders in laboratory medicine were agreed on. Firstly, to clarify the relevant changes covering all paragraphs of the standard and secondly to make an impact analysis on previous C: A/ISO guidance documents.

External quality assessment (EQA) enhances patient safety through the evaluation of the quality of laboratory-based and point of care testing. Regulatory agencies and accreditation organizations utilize the results and the laboratory's response to them as part of assessing the laboratory's fitness to practice. In addition, where EQA samples are commutable and the assigned value has been determined using reference measurement procedures (RMPs), EQA data contributes to the verification of metrological traceability of assays as part of the post-market surveillance of in vitro diagnostic (IVD) medical devices (IVD-MDs). More broadly, the scientific and medical communities use EQA data to demonstrate that medical laboratory examination procedures are fit for clinical purposes, to evaluate common reference intervals, and inclusion of data in clinical databases. Scientific groups, the IVD industry, reference laboratories and National Metrology Institutes can work with EQA providers to identify measurands, which should urgently be supported by the development of reference materials or methods. The ability of health systems to respond effectively to fast-evolving medical challenges, such as the Coronavirus Disease-19 (COVID-19) pandemic, is reliant on EQA to demonstrate confidence in the performance of new laboratory methods and testing services. EQA providers are uniquely positioned to assess the performance of IVD-MDs in addition to individual laboratories and testing sites. Although the primary focus of EQA providers remains the improvement of the performance of individual laboratories, there are many stakeholders who benefit from EQA performance data.

The main stakeholders in external quality assessment (EQA) programs are the participants, in whose interests these challenges are ultimately organised. EQA schemes in the medical field contribute to improving the quality of patient care by evaluating the analytical and diagnostic quality of laboratory and point-of-care tests (POCT) by independent third parties and, if necessary, pointing out erroneous measurement results and analytical or diagnostic improvement potential. Other benefits include the option of using EQA samples for other important laboratory procedures, such as the verification or validation of in vitro diagnostic medical devices (IVD-MDs), a contribution to the estimation of measurement uncertainty, a means of training and educating laboratory staff through educational EQA programmes or samples, or even for independent and documented monitoring of staff competence, such as on samples with unusual or even exceptional characteristics. Participation in an EQA scheme for beneficiaries like medical, microbiological and histo- and molecular pathology laboratories, users of POCT and self-testing systems as well as National Metrology Institutes, calibration laboratories and reference laboratories that are dedicated to specific tasks and have particular expectations of the EQA scheme are presented here.

Objectives: Prompt recognition of hyperammonaemia can avoid severe consequences of delayed treatment. Strict sample transport requirements present barriers to requesting and, if not achieved, rejection by the laboratory. Evidence is sparse on in vitro ammonia stability from studies using modern techniques or based in clinical settings. Stability in hyperammonaemic samples is unknown. This study aimed to examine ammonia stability and its source in samples from hyperammonaemic patients and to determine a clinically significant change to establish acceptable sample requirements for ammonia analysis.

Methods: Blood samples were taken from 19 hyperammonaemic patients and placed either on ice or kept at room temperature. Plasma ammonia was measured every 10 min for 2 h. Haemolysis index (HI), full blood count, liver enzymes and amino acids were analysed. Expert physicians were surveyed on a clinically significant ammonia change. Stability was assessed using the reference change value (RCV).

Results: Ammonia increased with time [peak value 14.9 % (8.4-17.1), median (95 % confidence interval)], and was predominately of cellular origin. Ice did not improve stability and increased HI. Survey results found a significantly increased ammonia between 39 % (30-48) at 50 μmol/L and 21 % (15-28) at 1,000 μmol/L. Ammonia RCV was 40.8 %.

Conclusions: Chilling samples did not improve blood ammonia stability. The increase in blood ammonia from patients with hyperammonaemia over 2 h was lower than that considered clinically significant and the calculated RCV. Transport of samples for ammonia analysis does not require ice and laboratories should accept samples if received within 2 h of venepuncture.

Providers of external quality assessment (EQA) programs evaluate data or information obtained and reported by participant laboratories using their routine procedures to examine properties or measurands in samples provided for this purpose. EQA samples must offer participants an equal chance to obtain accurate results, while being designed to provide results in clinically relevant ranges. It is the responsibility of the EQA provider to meet the necessary requirements for homogeneity, stability and some other properties of the EQA items in order to offer participants a fair, reliable and technically interesting EQA experience. Thus, the samples are at the heart and in the centre of EQA and its success depends on their quality. This manuscript describes the requirements for EQA samples and the activities of EQA providers to achieve them.

This is the first in a series of five papers that detail the role and substantial impact that external quality assessment (EQA) and their providers' services play in ensuring in-vitro diagnostic (IVD) performance quality. The aim is to give readers and users of EQA services an insight into the processes in EQA, explain to them what happens before EQA samples are delivered and after examination results are submitted to the provider, how they are assessed, what benefits participants can expect, but also who are stakeholders other than participants and what significance do EQA data and assessment results have for them. This first paper presents the history of EQA, insights into legal, financing and ethical matters, information technology used in EQA, structure and lifecycle of EQA programs, frequency and intensity of challenges, and unique requirements of extra-examination and educational EQA programs.

Objectives: To evaluate urinalysis parameters useful for identifying mixed cultures in urine culture using an automated urinary particle analyzer to assess quality indicators (QIs) for urine sample contamination.

Methods: A retrospective observational cross-sectional study was conducted with 2,527 urine samples from patients of a quaternary hospital in Brazil. Urine samples were processed simultaneously in Sysmex UF-5000 flow cytometry analyzer (urinalysis) and MALDI-TOF (culture).

Results: For all samples, a cutoff of 123.8 bacteria/µL was established to discriminate culture-negative specimens. ROC curve indicated the following cutoffs for females and males, respectively: 193.65 and 23.55 bacteria/µL, and 21.35 and 5.05 squamous epithelial cells (SEC)/µL, with the latter two related to scenarios of sample contamination/colonization through mixed cultures. Performing univariate logistic regression, we found a 2.78 (CI95 %: 2.12-3.65) times higher chance of probable mixed culture when SEC values were above the cutoffs for each sex, and 6.91(CI95 %: 4.56-10.47) times for bacteria. For multivariate logistic regression, the OR values were 1.62 (CI95 %: 1.21-2.15) and 5.82 (CI95 %: 3.77-8.98), respectively.

Conclusions: The fluorescent flow cytometry analyzers could efficiently identify urinary bacteria counts associated with contamination/colonization scenarios using the cutoffs of 21.35 SEC/µL for women and 5.05 SEC/µL for men. The cutoffs for bacteria/µL (193.65 for females and 23.55 for males) indicated that the presence of bacteria in male samples may be more associated with urinary tract infections (UTIs), while in female samples, it may be associated with either UTIs or contamination/colonization scenarios. This makes the analyzer a helpful tool as QI of sample contamination in urine cultures.

Objectives: An analytical protocol based on isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS), which includes a peptide-based calibration strategy, was developed and validated for the determination of cardiac troponin I (cTnI) levels in clinical samples. Additionally, the developed method was compared with a protein-based calibration strategy, using cTnI serving as a model for low-abundant proteins. The aim is to evaluate new approaches for protein quantification in complex matrices, supporting the metrology community in implementing new methods and developing fit-for-purpose SI- traceable peptide or protein primary calibrators.

Methods: To establish traceability to SI units, peptide impurity correction amino acid analysis (PICAA) was conducted to determine the absolute content of signature peptides in the primary standards. Immunoaffinity enrichment was used to capture cTnI from human serum, with a comparison between microbeads and nanobeads to improve enrichment efficiency. Parallel reaction monitoring was used to monitor two signature peptides specific to cTnI. Various digestion parameters were optimized to achieve complete digestion.

Results: The analytical method demonstrated selectivity and specificity, allowing the quantification of cTnI within 0.9-22.0 μg/L. The intermediate precision RSD was below 28.9 %, and the repeatability RSD was below 5.8 % at all concentration levels, with recovery rates ranging from 87 % to 121 %. The comparison of calibration strategies showed similar LOQ values, but the peptide-based calibration exhibited significant quantitative bias in recovery rates. The data are available via ProteomeXchange (PXD055104).

Conclusions: This isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) method, based on peptide calibration, successfully quantified cTnI in human serum. Comparing this with protein-based calibration highlighted both the strengths and potential limitations of peptide-based strategies.