Clinical chemistry and laboratory medicine最新文献

Objectives: Plasma renin activity (PRA) measures the rate of renin converting angiotensinogen to angiotensin I in circulation and reflects the function of renin-angiotensin-aldosterone system (RAAS). The study aimed to demonstrate the performance of the MAGLUMI Angiotensin I assay for the measurement of PRA.

Methods: The MAGLUMI Angiotensin I assay was evaluated for precision, linearity, limit of blank (LoB), limit of detection (LoD), limit of quantification (LoQ), interferences, cross-reactivity and reference intervals. It was compared to liquid chromatography tandem mass spectrometry (LC-MS/MS) using 54 samples, and impact of clinical factors was assessed in 181 samples.

Results: The assay demonstrated repeatability of 1.5 %, 1.85%, and 1.6 % across three different pool concentrations, with corresponding within-laboratory imprecision values of 2.0 %, 2.5%, and 1.9 %. The linear range was [0.10, 24.0] ng/mL. The LoB, the LoD, and the LoQ were 0.03 ng/mL, 0.07 ng/mL, and 0.10 ng/mL, respectively. The interferences and cross-reactivity met the criterion for acceptable cross-reactivity (CR) with <±10 %. Reference interval validation shows <10 % of a total of 40 healthy individuals' plasma samples falling outside the established interval for standing and lying position. The MAGLUMI assay showed excellent agreement with LC-MS/MS for both angiotensin I (slope=1.076, intercept=0.109 ng/mL/h, r=0.987, p<0.001) and plasma renin activity (slope=1.131, intercept=-0.386 ng/mL/h, r=0.973, p<0.001).

Conclusions: The MAGLUMI Angiotensin I chemiluminescence immunoassay is a sensitive and reliable commercial kit for detecting plasma renin activity. The assay exhibited robust analytical performance and strong agreement with LC-MS/MS.

Nowadays, we are facing major changes in the landscape of test harmonization through metrological traceability approach, all expected to promote equivalence of reported laboratory results. However, having traceability tools in place does not automatically mean that metrological traceability is correctly implemented. As concepts that are poorly implemented do not produce expected benefits, it is time to move from just discussing the effectiveness of traceability theory to how correctly implement it and effectively monitor its effects. In particular, considering the implementation outcomes, there is still a limited knowledge about the actual harmonization status of laboratory test results. We need to increase the information about the expected outcome by assessing result uniformity across different in vitro diagnostic medical devices (IVD-MDs) through an approach providing an ongoing robust evidence of standardization effectiveness. External Quality Assessment (EQA) programs have an irreplaceable role in this IVD traceability surveillance providing that they fulfill specific requirements. i.e., the use of commutable materials with target values assigned by reference measurement procedure (RMP) or strictly controlled procedures, if RMP does not exist, and with validation of results in relation to fit-for-purpose analytical performance specifications. If adequately designed, EQA programs can create evidence about intrinsic standardization status and equivalence of the examined IVD-MDs, serving as management tool for the medical laboratory and IVD manufacturers, and forcing them to investigate and eventually fix the identified problems. In this way, major stumbling blocks opposing the correct implementation of metrological traceability and the obtaining of harmonized laboratory results can be identified and removed.

Objectives: Lipoprotein(a) is an atherogenic particle causative of atherosclerotic cardiovascular disease. Novel treatments have been developed that lower lipoprotein(a) to unprecedented levels with cardiovascular outcomes trials ongoing. Many guidelines recommend testing once in the lifetime of everyone, but testing rates remain low. In this study we compare a lipoprotein(a) point of care testing device to laboratory analysers and assess its performance.

Methods: Lipoprotein(a) concentrations on residual patient samples measured on the Randox and Roche assays were compared to a novel point of care device, iProtin. Furthermore, assessment of iProtin performance characteristics were performed, including intra- and inter-assay coefficient of variation and dilutional studies.

Results: Lipoprotein(a) concentrations measured on the Randox and Roche assays showed strong correlation with iProtin. Regression analysis using Passing-Bablock showed the best fits for iProtin based on 58 serum samples were: 1.15 × Randox + 7.28 nmol/L and 1.02 × Roche + 17.54 nmol/L. The R² values for Randox/iProtin and Roche/iProtin were 0.906 and 0.912 respectively. Correlation between Roche and Randox showed Roche=1.15 × Randox - 13.33 nmol/L with an R² value of 0.973. Inter-assay coefficient of variation of the iProtin device showed a day-to-day imprecision over 5 days of 15.5 % (low concentration quality control) and 6.2 % (high concentration quality control). Within day imprecision was 13.2 % (lower concentration patient sample) and 14.3 % (higher concentration patient sample).

Conclusions: Point of care testing could be a complimentary option to laboratory testing of lipoprotein(a), especially in remote areas. It may help (re-)stratify cardiovascular risk and help tailor treatment decisions.

Objectives: Dried blood spot (DBS) sampling enables convenient at-home blood collection, suitable for patients needing regular check-ups, such as those receiving testosterone replacement therapy (TRT). This study assessed the feasibility and reliability of DBS sampling for monitoring testosterone concentrations in patients undergoing TRT, aiming to provide a convenient at-home alternative to venipuncture.

Methods: Twenty healthy volunteers (12F/8M) and 56 male patients (n=59 samples) receiving TRT were included. Blood was collected parallel by venipuncture (reference) and patient-performed finger prick (DBS) following instruction materials and additional verbal guidance from the andrology consultant. Feasibility and patients' experience were evaluated through questionnaires. Testosterone concentrations in both serum and DBS were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Results: In healthy volunteers, serum and DBS testosterone concentrations were highly correlated (y=-0.021 + 0.66x; r=0.99). For patients receiving intramuscular testosterone undecanoate, this correlation was strong (y=1.3 + 0.54x; r=0.87). However, DBS samples from patients using testosterone gel showed extremely elevated testosterone levels compared to serum, likely due to local contamination. Most healthy volunteers and in general all patients preferred at-home DBS-sampling over venipuncture at the hospital when regular check-ups are necessary, citing convenience and reduced travel time.

Conclusions: At-home DBS sampling is a feasible and reliable method for monitoring testosterone in patients treated with intramuscular testosterone undecanoate, improving patient comfort and convenience. However, DBS sampling at-home is currently unsuitable for patients using testosterone gel, likely due to contamination issues. Comprehensive patient education on collection of DBS samples is crucial to ensure high-quality DBS and accurate testosterone quantification.

Objectives: Complement inhibitor pegcetacoplan binds to C3 and its activation product C3b. Pegcetacoplan has been approved for the treatment of paroxysmal nocturnal hemoglobinuria. Because pegcetacoplan exerts broad inhibition of the complement cascade its efficacy is also investigated in numerous other diseases caused by complement dysregulation, such as C3 glomerulopathy. Pegcetacoplan causes a number of counterintuitive changes in laboratory results.

Methods: In-depth complement analysis in two patients with PNH and three patients with C3 glomerulopathy, all treated with pegcetacoplan.

Results: C3 levels increase up to 300 % above reference levels. In vitro testing showed that this is not a turbidimetric artifact in the C3 immunoassay due to pegcetacoplan-C3 complex formation but appears to be caused by increased half-life of C3 bound to pegcetacoplan. Unbiased mass spectrometric plasma proteome analysis confirmed the dramatic pegcetacoplan-induced increase in circulating C3. Surprisingly, also a three-fold increase of properdin was observed during pegcetacoplan treatment. Serum protein electrophoresis showed an additional band in all patients after pegcetacoplan exposure. This C3-band does not migrate at its expected position because of changes in the mass and charge of C3 bound to pegcetacoplan and should therefore not be misinterpreted as an M-protein. Both in vitro experiments and real clinical practice laboratory results demonstrated that pegcetacoplan completely blocked the alternative complement pathway while the classical pathway is affected but remains largely intact.

Conclusions: Because of the increasing use of pegcetacoplan in routine clinical practice, it is important that both clinicians and laboratory specialists are aware of these unexpected therapy-induced laboratory findings.

Objectives: Serum protein electrophoresis is one of the keystone investigations for screening for monoclonal proteins and assessing the serum protein profile. The newly released Helena V8ultra capillary electrophoresis system has been evaluated.

Methods: In total, 164 serum samples were assessed on the Helena V8 UltraCE system and compared with the Sebia Capillarys™ instrument. Abnormalities suggestive of monoclonal proteins were confirmed by immunosubtraction. Imprecision studies intervals were determined. Special attention was paid to complement C3 polymorphism.

Results: The imprecision of the Helena V8ultra was inferior or equal from 0.73 % (albumin) to 4.32 % (alpha₂ globulin). The mean bias of Helena V8ultraCE vs. Sebia Capillarys was about -0.225 % for albumin; -0.791 % for alpha₁ globulins; 1.353 % for alpha₂ globulins; -2.317 % for beta globulins; 0.066 % for gamma globulins. Among the 6 samples with monoclonal proteins confirmed by immunofixation, all were seen on both methods, with only 1 discordant result. The theoretical plate number (albumin fraction) was 2,371 ± 718 (Helena V8UltraCE) vs. 445 ± 115 (Sebia Capillarys 2). The high resolution also allows to distinguish Complement C3 phenotypes. CV values for the various fractions were low, ranging from 0.47 % (albumin) to 0.89 % (gamma globulins). IgG, IgA and IgM M-proteins could be detected in the electropherogram with an excellent sensitivity (<0.1 g/L).

Conclusions: Our evaluation confirms the good analytical performance of the Helena V8 analyzer as a suitable alternative to the Sebia Capillarys instrument. The high resolution allows detailed analysis of individual protein fractions which is an excellent basis for studying microheterogeneity.

Objectives: The performance of a novel urine particle analyzer, fluidlab 2 (Anvajo GmbH, Dresden, Germany), was evaluated against phase-contrast visual microscopy according to the most recent EFLM European Urinalysis Guideline.

Methods: The fluidlab 2 device combines digital holographic microscopy with neural network-based object detection for particle classification. Its compact benchtop design is suitable for bedside use, reducing turnaround times. The analytical performance (imprecision, linearity, LoQ) was evaluated according to the 2023 EFLM Urinalysis Guideline. Method comparison involved the analysis of 450 urine samples, assessing RBC, WBC, and SEC counts against visual microscopy using Passing-Bablok regression and Spearman's correlation. Bland-Altman plots were used to evaluate the agreement with clinical performance standards, while weighted Cohen's kappa was used to measure diagnostic agreement on an ordinal scale.

Results: By applying Dahlberg's procedure, a desirable relative coefficient of variation R(CV) ≤2.0 was obtained for RBC and WBC. Linearity of up to 7 × 10⁶/L and 6 × 10⁶/L was achieved. The estimated LoQ at CV=30 % reached 20 × 10⁶/L for RBC and 5 × 10⁶/L for WBC. Spearman's correlation coefficient against visual microscopy was 0.86, 0.92 and 0.94 for RBC, WBC and SEC, respectively. Agreement with visual microscopy (Cohen's weighted kappa) was 0.92 for RBC, 0.93 for WBC, 0.96 for SEC, 0.86 for casts, 0.82 for non-SEC, 0.33 for crystals and 0.51 for bacterial counts.

Conclusions: Fluidlab 2 provides desirable imprecision for RBC and WBC, and meets the criteria for linearity and LoQ. Cohen's weighted kappa coefficients show an optimal comparison to visual microscopy for RBC, WBC and SEC and a minimum comparison for casts and non-SEC. This evaluation demonstrated promising results for the use of the fluidlab 2 analyzer in a clinical setting to detect kidney-related diseases based on urine particle analysis.

Agentic artificial intelligence (AI) systems are distinguished by their ability to invoke multiple tools, compose command chains, and combine chain-of-thought reasoning with deep research to execute complex tasks and take actions. This represents a major evolution beyond machine learning and large language models (LLM), toward systems capable of planning, executing, and coordinating complex workflows. In contrast to traditional LLMs, which primarily focus on generating and classifying information, agentic AI introduces elements of autonomy, reasoning, and orchestration, while digital twins extend this concept to dynamic virtual representations of patients and laboratory processes, capable of continuous learning, simulation and adaptation. This transition has profound implications for laboratory medicine, a field characterized by high data complexity, multi-omics integration, and stringent operational demands. At the same time, laboratories face growing expectations regarding efficiency, resource stewardship, and value-based healthcare delivery. This article explores both the opportunities and limitations of agentic AI in laboratory medicine, highlighting its potential to move beyond static automation toward autonomous, outcome-driven innovation. It also examines the ethical, interpretability, and governance considerations that must accompany its implementation.

Objectives: Compare Elecsys (Roche) and Simoa (Quanterix) immunoassays for serum glial fibrillary acidic protein (GFAP) using our reference database and Z scores, and evaluate their prognostic value for progression independent of relapse activity (PIRA) in multiple sclerosis (MS).

Methods: Platform correlation was assessed in 612 samples from healthy controls (n=188; median [interquartile range, IQR] age 45.1 [36.4-61.7] years) and people with MS (n=424; 45.3 [35.2-53.9] years). Elecsys values were converted to Z scores via Passing-Bablok-derived regression and validated in fingolimod (n=414), and B-cell depleting therapy (BCDT; n=353) cohorts. Z scores and hazard ratios (HRs) for time-to-PIRA were compared using Cox regression.

Results: GFAP_Simoa and GFAP_Elecsys measurements were correlated (r=0.94), with Elecsys values ∼54 % lower (GFAP_Elecsys, ng/L=2.847 [95 % confidence interval, CI: 1.335 - 4.98] + 0.457 [0.434 - 0.478] * GFAP_Simoa, ng/L). In univariable Cox models, GFAP_Simoa and GFAP_Elecsys Z scores were associated with time-to-PIRA in both validation cohorts. In multivariable Cox models, higher GFAP_Simoa Z scores were associated with shorter time-to-PIRA in fingolimod cohort (HR: 1.27 [95 % CI 1.08 - 1.50], p=0.0031) and trended toward significance in BCDT (1.18 [0.99 - 1.41, p=0.0693). In contrast, GFAP_Elecsys Z scores were associated with time-to-PIRA in both cohorts (fingolimod: 1.27 [1.09 - 1.48], p=0.0023; BCDT: (1.19 [1.00 - 1.40], p=0.0487).

Conclusions: Serum GFAP measured by Elecsys shows a comparable association with time-to-PIRA as Simoa, and GFAP_Simoa Z scores can be successfully bridged to GFAP_Elecsys Z scores, supporting Elecsys`s potential for clinical implementation.