Volume 63, Issue 3

Extracellular vesicles (EVs) represent a diverse class of nanoscale membrane vesicles actively released by cells. These EVs can be further subdivided into categories like exosomes and microvesicles, based on their origins, sizes, and physical attributes. Significantly, disease-derived EVs have been detected in virtually all types of body fluids, providing a comprehensive molecular profile of their cellular origins. As a result, EVs are emerging as a valuable addition to liquid biopsy techniques. In this collective statement, the authors share their current perspectives on EV-related research and product development, with a shared commitment to translating this newfound knowledge into clinical applications for cancer and other diseases, particularly as disease biomarkers. The consensus within this document revolves around the overarching recognition of the merits, unresolved questions, and existing challenges surrounding EVs. This consensus manuscript is a collaborative effort led by the Committee of Exosomes, Society of Tumor Markers, Chinese anti-Cancer Association, aimed at expediting the cultivation of robust scientific and clinically applicable breakthroughs and propelling the field forward with greater swiftness and efficacy.

Arginine vasopressin (AVP) plays a main role in maintaining the homeostasis of fluid balance and vascular tone and in regulating the endocrine stress response in response to osmotic, hemodynamic and stress stimuli. However, the difficulty in measuring AVP limits its clinical application. Copeptin, the C-terminal part of the AVP precursor, is released in an equimolar concentration mode with AVP from the pituitary but is more stable and simple to measure. Therefore, copeptin has emerged as a promising surrogate marker of AVP with excellent potential for the diagnosis, differentiation and prognosis of various diseases in recent decades. However, its application requires further validation, especially in the pediatric population. This review focuses on the clinical value of copeptin in different pediatric diseases and the prospects for its application as a potential biomarker.

The biotechnology company Grail developed a non-invasive blood test (Galleri test) which is claimed to detect 50 types of cancer at early and potentially curable stages. The initially promising results from prospective studies, and the anticipated financial success of Grail led the sequencing giant Illumina to purchase Grail for $8 billion (2021). Following this event, Grail collaborated with the UK National Health System to further clarify the test’s capability, in a 3-year prospective trial, along with the standard of care. The UK-NHS announced that the trial will provide a clearer understanding of the efficacy of the Galleri test within the NHS framework. If the test does not perform as expected, valuable insights will still be gained to guide future research aimed at enhancing cancer screening. We previously expressed concerns about the sensitivity and specificity of the Galleri test. In this opinion paper, we revisit the hyped technology, and we provide new suggestions on the use of this test.

Background In laboratory setting evaluating the agreement between two measurement methods is a very frequent practice. Unfortunately, the guidelines to refer to are not free from criticisms from a statistical methodological point of view. We reviewed the Clinical and Laboratory Standards Institute guideline EP09c, 3rd ed. pointing out some drawbacks and some aspects that have not been well defined, leaving situations of uncertainty and/or of excessive subjectivity in the judgement. Content We have stressed the need of having replicates to estimate the systematic and the proportional biases of the measurement methods to be compared. Indeed, unequal variance of the two measurement methods gives a slope and intercept of the regression between the difference and the mean of the two values of the measurement methods to be compared that can be absolutely calculated from their means, their variances and their correlation coefficient. So, it is not possible to disentangle true from spurious biases. For laboratory professionals we have developed a worked exemplification of an agreement assessment. Summary We have stressed the need of other approaches than the classic Bland and Altman method to calculate the systematic and proportional biases of two measurement methods compared for their agreement in a study with replicates.

Serum and pleural fluid tumor markers are well-recognized auxiliary diagnostic tools for malignant pleural effusion (MPE). Here, we discuss some pearls and pitfalls regarding the role of tumor markers in MPE management. The following issues are discussed in this article: What is the appropriate clinical scenario for evaluating pleural tumor markers? Which tumor markers should be advocated for diagnosing MPE? Can extremely high levels of tumor markers be employed to establish a diagnosis of MPE? Does the serum-to-pleural fluid ratio of a tumor marker have the same diagnostic efficacy as the measurement of that marker alone in the pleural fluid? Can tumor markers be used to estimate the risk of specific cancers? What should be considered when interpreting the diagnostic accuracy of tumor markers? How should tumor marker studies be performed? We addressed these issues with published works, particularly systematic reviews and meta-analyses.

This opinion article highlights the critical role of laboratory medicine and emerging technologies in cardiovascular risk reduction through exposome analysis. The exposome encompasses all external and internal exposures an individual faces throughout their life, influencing the onset and progression of cardiovascular diseases (CVD). Integrating exposome data with genetic information allows for a comprehensive understanding of the multifactorial causes of CVD, facilitating targeted preventive interventions. Laboratory medicine, enhanced by advanced technologies such as metabolomics and artificial intelligence (AI), plays a pivotal role in identifying and mitigating these exposures. Metabolomics provides detailed insights into metabolic changes triggered by environmental factors, while AI efficiently processes complex datasets to uncover patterns and associations. This integration fosters a proactive approach in public health and personalized medicine, enabling earlier detection and intervention. The article calls for global implementation of exposome technologies to improve population health, emphasizing the need for robust technological platforms and policy-driven initiatives to seamlessly integrate environmental data with clinical diagnostics. By harnessing these innovative technologies, laboratory medicine can significantly contribute to reducing the global burden of cardiovascular diseases through precise and personalized risk mitigation strategies.

The 2024 Kidney Disease: Improving Global Outcomes (KDIGO) guidelines for chronic kidney disease (CKD) evaluation and management bring important updates, particularly for European laboratories. These guidelines emphasize the need for harmonization in CKD testing, promoting the use of regional equations. In Europe, the European Kidney Function Consortium (EKFC) equation is particularly suited for European populations, particularly compared to the CKD-EPI 2021 race-free equation. A significant focus is placed on the combined use of creatinine and cystatin C to estimate glomerular filtration rate (eGFRcr-cys), improving diagnostic accuracy. In situations where eGFR may be inaccurate or clinically insufficient, the guidelines encourage the use of measured GFR (mGFR) through exogenous markers like iohexol. These guidelines emphasize the need to standardize creatinine and cystatin C measurements, ensure traceability to international reference materials, and adopt harmonized reporting practices. The recommendations also highlight the importance of incorporating risk prediction models, such as the Kidney Failure Risk Equation (KFRE), into routine clinical practice to better tailor patient care. This article provides a European perspective on how these KDIGO updates should be implemented in clinical laboratories to enhance CKD diagnosis and management, ensuring consistency across the continent.

Objectives Expanded carrier screening (ECS) is a preventive genetic test that enables couples to know their risk of having a child affected by certain monogenetic diseases. This study aimed to evaluate the carrier frequency for rare monogenic diseases in the general Chinese population and the impacts of ECS on their reproductive decisions and pregnancy outcomes. Methods This single-center study was conducted between September 2022 and April 2023. An ECS panel containing 224 recessive genes was offered to 1,499 Chinese couples from the general population who were at early gestational ages or planned to conceive. Results Overall, 55.0 % of the individuals carried for at least one recessive condition. There were 16 autosomal recessive (AR) genes with a carrier frequency of ≥1/100 and 22 AR genes with a carrier frequency of <1/100 to ≥1/200. The most common AR and X-linked diseases were GJB2 -related non-syndromic hearing loss, and hemolytic anemia, respectively. Fifty-five couples (3.67 %; 1 in 27.3) were at increased risk of having an affected child with 19 pregnant at the time of testing. Of these, 10 opted for amniocentesis, and four affected pregnancies were identified, with three of them being terminated. Conclusions This study not only provides valuable information about the recessive genetic landscape, but also establishes a solid foundation for couple-based ECS in a real clinical setting.

Objectives Lab testing is a high-volume activity that is often overused, leading to wasted resources and inappropriate care. Improving test ordering practices in tertiary care involves deciding where to focus scarce intervention resources, but clear guidance on how to optimize these resources is lacking. We aimed to explore context-sensitive factors and processes that inform individual decisions about laboratory stewardship interventions by speaking to key interest holders in this area. Methods We conducted semi-structured interviews with test-ordering intervention development experts and authors of test-ordering guidance documents to explore five broad topics: 1) processes used to prioritize tests for intervention; 2) factors considered when deciding which tests to target; 3) measurement of these factors; 4) interventions selected; 5) suggestions for a framework to support these decisions. Transcripts were double coded using directed-content and thematic analysis. Results We interviewed 14 intervention development experts. Experts noted they frequently consider test volume, test value, and patient care when deciding on a test to target. Experts indicated that quantifying many relevant factors was challenging. Processes to support these decisions often involved examining local data, obtaining buy-in, and relying on an existing guideline. Suggestions for building a framework emphasized the importance of collaboration, consideration of context and resources, and starting with “easy wins” to gain support and experience. Conclusions Our study provides insight into the factors and processes experts consider when deciding which tests to target for intervention and can inform the development of a framework to guide the selection of tests for intervention and guideline development.

Objectives Until now, the external quality assessment (EQA) of glucose point-of-care testing (POCT) has lacked a high quality, suitable and commutable control material to assess measurement accuracy. Here we present a concept for determining the accuracy of glucose measurements, which uses human whole blood and does not require stabilising agents. Methods This new generation of quality control samples uses a bead that contains a specific amount of glucose. The bead is then dissolved in a whole blood matrix by the EQA participant immediately before the POCT. We analysed its suitability as an EQA material with respect to its reproducibility, homogeneity and stability, and applied it in an EQA pilot study. The glucose target value was determined using the reference measurement procedure and served as an evaluation criterion for the accuracy of the EQA survey results. Results The homogeneity and stability of the new control material fulfilled the quality requirements of ISO 17043. Based on the reference measurement value for glucose, the results of the pilot EQA scheme showed a pass rate of 84.6 % for the participating POCT devices. The acceptance limit was a 15 % permitted deviation from the target value according to Rili-BAEK. All of the device collectives deviated from the target value by 0–4.4 % with the exception of one device type, which deviated by 21 %. Conclusions The new concept offers, for the first-time, whole blood-based trueness controls for glucose POCT analysis for external quality assurance. The concept does not require the addition of any stabilising reagent and is easy to use.

Objectives The identification of vitamin B12 (B12) deficiency in the newborn may prevent neurological damage and a delay in the normal growth. In this study we characterized the incidence of B12 deficiency in newborns, the costs associated to the clinical diagnosis and management, and the relevance to optimize the use of cobalamin biomarkers during treatment follow-up. Methods Starting from a continuous case series of 146,470 screened newborns (November, 1st 2021- December, 3rd 2023), the Regional Reference Laboratory for Neonatal Screening identified 87 newborns having altered levels of biomarkers of cobalamin metabolism measured by newborn screening. These subjects were confirmed with a nutritional B12 deficiency of maternal origin by performing the serum B12 measurements and plasma homocysteine (Hcy) both on the newborns and respective mothers. A cost analysis was performed to characterize the costs/year of identifying and managing B12 deficiency cases. Results At baseline, median (interquartile range) serum B12 levels of 185.0 (142.3–246.0) ng/L and threefold increased plasma Hcy concentrations above the normal level confirmed a severe condition of deficiency in the newborns. After intramuscular B12 supplementation, serum B12 measured at the first follow up visit showed a fivefold increase, and the levels of Hcy returned to normal. From the healthcare perspective, the costs for diagnosing and managing all newborns with B12 deficiency is 188,480 €/year. Conclusions Preventing B12 depletion in newborns lowers healthcare costs and likely improves their health outcomes. Further studies are however required to address the clinical pathway to identify, treat and monitor pregnant women with marginal and low B12 status, in order to achieve these goals.

Objectives Qualitative faecal immunochemical tests for haemoglobin (FIT), for triaging for colorectal cancer investigations, are available for professional use. The aim was to evaluate these lateral flow tests. No previous analytical evaluations have been published. Methods Analytical sensitivity (AS) was assessed using samples spanning manufacturers’ quoted AS, concurrently with the quantitative OC-SENSOR PLEDIA, using Hb-spiked samples in manufacturers’ buffer (n≥5; ≤9–99 ng Hb/mL buffer), Hb-spiked feces (n=6; <2–34 µg Hb/g feces) and natural feces (n=17; <2–82 μg/g); concentrations for 50 %/100 % Hb-detected were compared with quoted AS. Compatibility with two external quality assessment schemes (EQAS) (n=9; 3–96 μg/g) and prozone compared with manufacturers limits (n=9; 2,500–10,000,000 ng/mL) were tested. Ease-of-use by five healthcare personnel was assessed. Results Seven products showed lower AS (ng/mL) than manufacturers quoted using Hb-spiked aqueous samples compared with OC-SENSOR, one was equivocal; six manufacturers quoted AS in µg/g, five showed lower AS using Hb-spiked feces. Results were similar but less consistent for natural feces. Result lines for low concentrations can be faint and open to interpretation. Results were consistent with manufacturers quoted prozone limits. Results were consistent for seven products for two EQAS. The ease-of-use was 68.5–85.6 %; products with lower scores could be improved with better instructions and sample bottles. Conclusions AS was lower for seven products (aqueous samples) and five products (aqueous/faecal samples) and prozone consistent with manufacturers expected concentrations, compared with OC-SENSOR. EQAS results were mostly consistent with expected results; products can be used by healthcare professionals, though some manufacturer improvements could be made.

Objectives Fecal immunochemical tests (FIT) for hemoglobin are currently considered the screening investigation of choice for colorectal cancer and are worldwide recommended. Similarly, fecal calprotectin is a widely used test for monitoring intestinal inflammation. The pre-analytical issues regarding stool samples have hardly been dealt with and are difficult to solve. Currently, there are no reference analytes available which allow to correct test results for the variable water content of the stool sample. Studies on preanalytics of stool samples have generally focused on sample preparation and sample storage, but generally have paid little attention to the variability in sample hydration and sample composition. Methods Stercobilin is a stable heme metabolite which is abundant in stool. Stercobilin concentration can be simply assayed in stool extracts using colorimetry (determination of the I index). Serum indices (H, I and L) and bilirubin concentration of fecal extracts were determined on a Atellica Platform (Siemens). Results The inter-individual variation of stercobilin was found to be high. Assaying stercobilin allows to correct for stool sample dilution. The median value of the I-index was used as a reference for correcting the data. Correcting fecal blood results for sample dilution resulted in a significant increase in positive tests (from 9.3 to 11.7 %). For calprotectin, correction resulted in 3.1 % extra positive results and 7.7 % negative results. Conclusions Except in the case of obstructive jaundice, this correction can be applied. Correcting test results of common fecal analytes like FIT and calprotectin may result in a better tailored test interpretation.

Objectives Diurnal variation of plasma glucose levels may contribute to diagnostic uncertainty. The permissible time interval, pT ( t ), was proposed as a time-dependent characteristic to specify the time within which glucose levels from two consecutive samples are not biased by the time of blood collection. A major obstacle is the lack of population-specific data that reflect the diurnal course of a measurand. To overcome this issue, an approach was developed to detect and assess diurnal courses from big data. Methods A quantile regression model, QRM, was developed comprising two-component cosinor analyses and time, age, and sex as predictors. Population-specific canonical diurnal courses were generated employing more than two million plasma glucose values from four different hospital laboratory sites. Permissible measurement uncertainties, pU , were also estimated by a population-specific approach to render Chronomaps that depict pT ( t ) for any timestamp of interest. Results The QRM revealed significant diurnal rhythmometrics with good agreement between the four sites. A minimum pT ( t ) of 3 h exists for median glucose levels that is independent from sampling times. However, amplitudes increase in a concentration-dependent manner and shorten pT ( t ) down to 72 min. Assessment of pT ( t ) in 793,048 paired follow-up samples from 99,453 patients revealed a portion of 24.2 % sample pairs that violated the indicated pT ( t ). Conclusions QRM is suitable to render Chronomaps from population specific time courses and suggest that more stringent sampling schedules are required, especially in patients with elevated glucose levels.

Objectives Iron deficiency anemia is a significant global health concern, diagnosed by measuring hemoglobin concentrations in combination with plasma ferritin concentration. This study investigated the variability in ferritin reference intervals among laboratories in the Netherlands and examined how this affects the identification of iron-related disorders. Methods Ferritin reference intervals from 52 Dutch ISO15189-certified medical laboratories were collected. Ferritin, hemoglobin and mean corpuscular volume data of non-anemic apparently healthy primary care patients, measured by four laboratory platforms (Beckman, Abbott, Siemens, and Roche), were collected (n=397,548). Median ferritin levels were determined per platform, stratified by sex and age. The proportion of ferritin measurements outside of the reference interval was calculated using the reference intervals from the 52 laboratories (using a total of n=1,093,442 ferritin measurements). Lastly, ferritin data from 3,699 patients as captured in general practitioner (GP) data from the PHARMO Data Network were used to assess the variation of abnormal ferritin measurements per GP. Results Median plasma ferritin concentrations were approximately four times higher in men and twice as high in postmenopausal women compared to premenopausal women. Moreover, there are substantial differences in the median plasma ferritin concentration between the four platforms. However, even among laboratories using the same platform, ferritin reference intervals differ widely. This leads to significant differences in the percentages of measurements classified as abnormal, with the percentage of ferritin measurements below the reference limit in premenopausal women ranging from 11 to 53 %, in postmenopausal women from 3 to 37 %, and in men from 2 to 19 %. The percentage of ferritin measurements above the reference limit in premenopausal women ranged from 0.2 to 11 %, in postmenopausal women from 3 to 36 % and in men from 7 to 32 %. Conclusions The lack of harmonization in ferritin measurement and the disagreement in plasma ferritin reference intervals significantly impact the interpretation of the iron status of patients and thereby the number of iron disorder diagnoses made. Standardization or harmonization of the ferritin assays and establishing uniform reference intervals and medical decision limits are essential to reduce the substantial variability in clinical interpretations of ferritin results.

Objectives As thyroid disorders are common amongst the elderly, this study aims to evaluate the reference interval (RI) for thyroid stimulating hormone (TSH) in healthy adults aged 70 years and over. Methods A proposed RI was determined from the Australian participants of the ASPirin in Reducing Events in the Elderly (ASPREE) randomised trial. Participants had no history of cardiovascular disease, thyroid cancer, dementia, or life-threatening illnesses. Participants prescribed with any thyroid-related medication at baseline were excluded. TSH levels were measured using a commercial chemiluminescence microparticle immunoassay. The RI was determined using the middle 95th percentile of the logarithmic transformed data of baseline TSH. Cox proportional hazard regression models were used to validate the RI by assessing disease incidence over time. Results A total of 10,995 participants had baseline TSH measures. Median (IQR) age was 73.9 (71.8–77.3) years. We propose a RI of 0.34–3.75 mU/L. TSH levels did not differ by age or sex. At baseline, there was no association between symptoms associated with thyroid disease and levels of TSH. Over the follow-up period of up to 11 years, no association was seen between baseline TSH levels and relevant disease outcomes for participants within the RI. Conclusions From a group of initially healthy, community-dwelling adults aged >=70 years, we propose a RI of TSH to best represent euthyroidism. This concentration was not associated with an increased risk of thyroid related symptoms or outcomes, confirming its appropriateness for clinical use.

Objectives The development of External Quality Assessment Schemes (EQAS) for clinical flow cytometry (FCM) is challenging in the context of rare (immunological) diseases. Here, we introduce a novel EQAS monitoring the primary immunodeficiency Orientation Tube (PIDOT), developed by EuroFlow, in both a ‘wet’ and ‘dry’ format. This EQAS provides feedback on the quality of individual laboratories (i.e., accuracy, reproducibility and result interpretation), while eliminating the need for sample distribution. Methods In the wet format, marker staining intensities (MedFIs) within landmark cell populations in PIDOT analysis performed on locally collected healthy control (HC) samples, were compared to EQAS targets. In the dry format, participants analyzed centrally distributed PIDOT flow cytometry data (n=10). Results We report the results of six EQAS rounds across 20 laboratories in 11 countries. The wet format (212 HC samples) demonstrated consistent technical performance among laboratories (median %rCV on MedFIs=34.5 %; average failure rate 17.3 %) and showed improvement upon repeated participation. The dry format demonstrated effective proficiency of participants in cell count enumeration (range %rCVs 3.1–7.1 % for the major lymphoid subsets), and in identifying lymphoid abnormalities (79.3 % alignment with reference). Conclusions The PIDOT-EQAS allows laboratories, adhering to the standardized EuroFlow approach, to monitor interlaboratory variations without the need for sample distribution, and provides them educational support to recognize rare clinically relevant immunophenotypic patterns of primary immunodeficiencies (PID). This EQAS contributes to quality improvement of PID diagnostics and can serve as an example for future flow cytometry EQAS in the context of rare diseases.

Objectives A smear review is typically made in flagged differential counts performed with hematology analyzers although the clinical value of such reviews is uncertain. Therefore, we evaluated the differences in differential counts between Sysmex XN-9000 and a smear review in flagged samples. Furthermore, the clinical value of blasts identified was investigated. Methods Data on all differential counts performed in a two-year period were identified at two laboratories. In patients with blasts, the electronic health record was reviewed. Agreement between automated and manual differential counts was evaluated by Bland-Altman plots. Concordance between the two methods categorized according to reference intervals was evaluated and adjusted for irrelevant non-concordance caused by random analytical error. Results In total, 5,500 flagged differential counts were identified from 4,092 patients. A good agreement between the automated and manual differential count was found for all cell types (−0.480 × 10 9 /L to 0.297 × 10 9 /L). The concordance between the two methods was excellent for all cell types, except for monocytes (82 %) where the automated estimates were higher than the manual in 19 % of samples. Blasts were identified in 241 (1 %) of smear reviews. Acute leukemia was diagnosed in 13 (5 %) patients, and only in one patient contributed the detection of blasts to the suspicion of acute leukemia. Conclusions Our findings indicate that routine smear review of all flagged samples do not contribute with additional, significant information. After local validation and dialogue with clinical departments, such reviews may potentially be omitted to increase cost-effectiveness and reduce turn-around-time.

Objectives 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). Methods 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). Results 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). Conclusions 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.