Clinical chemistry and laboratory medicine最新文献

Introduction: The increasing use of therapeutic monoclonal antibodies (t-mAbs) has improved cancer and autoimmune disorder treatment. These therapeutics can interfere with serum protein electrophoresis (SPEP) and immunofixation (IF), potentially leading to the appearance of monoclonal bands that may be misinterpreted as monoclonal gammopathies. Identifying the migration patterns and detection thresholds of t-mAbs is crucial to avoid misinterpretation in clinical laboratories.

Content: A systematic review following PRISMA guidelines was conducted using Pubmed and ScienceDirect databases, with algorithm-based searches and double-blind article selection. Data on the matrix used, separation methods and type of interference were collected into an extraction table.

Summary: A total of 30 articles were included and 30 t-mAbs were described. 11 t-mAbs migrated at the end of the gamma region, 12 in the mid-gamma region, 5 in the early gamma region, one in the beta-2 globulin region and one in the alpha-2 globulin region. Most t-mAbs were detectable by SPEP and IF at concentrations above 100 mg/L.

Outlook: Caution is needed when a new peak appears on SPEP, as it may be mistaken for a monoclonal spike leading to misdiagnosis. Therefore, understanding the migration profiles of these t-mAbs is essential. Different methods are available to remove t-mAbs interference and could be used in daily practice.

Objectives: Accurate quantification of aldosterone is critical for screening and diagnosing primary aldosteronism (PA). Current competitive chemiluminescence immunoassays (cCLIA) overestimate plasma aldosterone concentration (PAC) compared to liquid chromatography-tandem mass spectrometry (LC-MS/MS). However, LC-MS/MS is technically demanding and time-consuming, limiting its widespread clinical utility. Therefore, a novel two-step sandwich chemiluminescence immunoassay (sCLIA) for accurate quantification of PAC was systematically evaluated.

Methods: Precision, trueness, linear range, and maximum dilution factor of the new immunoassay were comprehensively validated. In a multicenter study involving 2,696 samples from seven Chinese centers, PAC measurements were performed in parallel using sCLIA, cCLIA, and LC-MS/MS. The study specifically focused on evaluating the assay's performance at low aldosterone concentrations and in patients with chronic kidney disease (CKD), investigating potential interference from renal impairment by comparing the consistency between immunoassays and LC-MS/MS results across different CKD stages.

Results: The sCLIA exhibited excellent analytical performance for PAC measurement, with intra-assay imprecision <4.64 % and bias <5.71 % against certificated reference materials. The assay exhibited a wide reportable range (30-100,000 ng/L) with a limit of quantification at 30 ng/L and dilution capability ≥50-fold. Compared to cCLIA, sCLIA showed superior agreement with LC-MS/MS, particularly at low PAC concentrations (<110 ng/L) and in subjects with reduced renal function (eGFR<60 mL/min/1.73 m²).

Conclusions: This novel sCLIA method exhibited excellent analytical performance, combining the practical advantages of immunoassays with LC-MS/MS accuracy, thereby offering an ideal solution for large-scale primary aldosteronism screening in clinical practice.

Objectives: Glial fibrillary acidic protein (GFAP) is a well-established biomarker of astrocytic activation associated with neurodegenerative diseases, neuroinflammatory disorders, and traumatic brain injury. With increasing interest in blood-based biomarkers, the need for analytically validated assays and reliable reference intervals is critical for routine clinical implementation. This study aimed to analytically validate the MSD S-Plex^® GFAP immunoassay for plasma and to establish age-stratified reference intervals in an apparently healthy population.

Methods: This study was conducted in two phases. First, key analytical validation parameters - including repeatability, intermediate precision, measurement range, interferences, and sample stability - were evaluated following Clinical and Laboratory Standards Institute (CLSI) and published protocol guidelines. Second, reference intervals were derived from 579 apparently healthy individuals aged 17-91 years using a right-sided non-parametric percentile method. Age-specific upper reference limits were calculated for three predefined age groups, and a continuous age-dependent centile model was applied.

Results: MSD S-Plex^® GFAP assay demonstrated strong analytical performance, with coefficients of variation for repeatability and intermediate precision below 12 %. After accounting for the 1:2 dilution ratio, the validated measurement range was 0.425-1760 ng/L, with all calibration residuals remaining within ±15 %. GFAP concentrations were unaffected by hemolysis (p=0.85) and remained stable for up to 7 days at 4 °C and under frozen storage conditions. Age-stratified upper reference limits for plasma GFAP were established as 38 pg/mL (18-<50 years), 73 pg/mL (≥50-<70 years), and 156 pg/mL (≥70 years). Additionally, sex-related differences were observed after age 50, with females showing higher absolute GFAP levels than males. A strong positive correlation between age and plasma GFAP levels was observed (Spearman's r=0.832, p<0.0001).

Conclusions: This study demonstrates the robust analytical performance of the MSD S-Plex^® GFAP assay and establishes age-related reference values for plasma GFAP. These findings support its suitability for routine clinical use and enhance its applicability in the diagnosis and monitoring of central nervous system (CNS) pathologies, such as neurodegenerative diseases, neuroinflammatory disorders, and acute brain injuries, within biomarker-supported clinical algorithms.

Objectives: Measurement uncertainty (MU) plays an important role in the interpretation of laboratory results, but data on serum proteins analyzed by immunoturbidimetry according to ISO/TS 20914 are limited.

Methods: MU of 11 serum proteins, including CRP, RF, ASO, IgG, IgA, IgM, C3, C4, ceruloplasmin, transferrin, and β2-microglobulin, were estimated using 1-year internal quality control (IQC) data obtained from Roche Cobas analyzers. MU was calculated using uncertainty and calibrator uncertainty according to ISO/TS 20914, assuming negligible deviation from external quality assessment data. Analytical performance specification (APS) models were selected according to the EFLM APS selection criteria, and maximum allowable uncertainty (MAU) values were determined based on sources such as EFLM models and literature.

Results: IgA and RF were the only two analytes that met the required and minimum MAU values, respectively, at both IQC levels. MU values for CRP, ceruloplasmin, transferrin, and β2-microglobulin exceeded targets at both levels. MU for C3, C4, IgG, and IgM exceeded the minimum MAU at IQC1 but remained acceptable at IQC2. MU values for ASO were calculated as 10.01 and 7.22 % but could not be evaluated due to a lack of reference data. Assay precision should be improved for CRP, IgG, IgM, ceruloplasmin, transferrin, and β2-microglobulin. Use of updated calibration materials for CRP may help reduce MU.

Conclusions: Maintaining acceptable precision over a long period remains a challenge for serum proteins analyzed by immunoturbidimetry, highlighting the need for methodological improvements and stricter quality monitoring. In this context, MU assessment is crucial.

Laboratory data can be meaningful only when compared with reliable reference data; therefore, the estimation of reliable reference data is just as important as the accurate measurement of measurands in patient samples. Since analyte concentrations in the human body are influenced by both random variations (such as biological fluctuations) and systematic variations (such as physiological rhythms and age-related changes), the conventional model for estimating reference data - based solely on the statistical distribution of single-sample measurements from reference individuals - may not provide sufficiently reliable information for interpreting patient results. Therefore, a paradigm shift from relying solely on single-sample measurement distributions to incorporating metabolic changes observed in the human body when estimating reference intervals may enhance the clinical value of laboratory data for an effective clinical decision making and patient care. This opinion paper aims to summarize how to facilitate this transition and to identify the most suitable model for estimating reference intervals that reflect underlying metabolic dynamics.

Objectives: Quantitation of plasma amino acids (AA) is critical for the diagnosis and monitoring of inherited disorders of AA metabolism. AA analysis using ion-exchange chromatography (IEC) with post-column ninhydrin derivatization is time consuming, with run times of ∼2 h, limiting sample throughput. Liquid chromatography mass-spectrometry can potentially address some of the current challenges.

Methods: Performance of components of the Waters Kairos Amino Acid Kit using liquid chromatography single quadrupole mass-spectrometry (LC-MS) following derivatization of samples with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AccQ•Tag™ Ultra Derivatization Reagent) was evaluated. Results were compared with the Biochrom-IEC method using patient specimens (n=115), ClinChek^® control and external quality assessment (EQA) material.

Results: The kit reagents and our developed method had a 19-min analysis time, demonstrated acceptable inter-assay imprecision (CV<10 %) and bias vs. IEC-method (overall mean bias <2 %). Excellent correlation (concordance correlation coefficient (CCC) >0.99) with IEC was demonstrated for 10/23 analytes, good correlation (CCC >0.95) for 10/23, with the remaining three amino acids (aspartate, histidine and tryptophan) demonstrating moderate concordance (CCC ≥0.90 but <0.95). 1/23 AAs had a mean bias >10 % using EQA material. The method demonstrated a lower limit of quantitation of ≤2.5 μmol/L for all AA, making this assay suitable for CSF analysis. Calibration stability bias was <5 % over 12-weeks. Derivatized AAs were stable for ≤17 days. The analytical column supplied demonstrated good retention time stability (<0.4 %) and was capable of >2000 injections.

Conclusions: The tested methodology demonstrated good analytical performance and correlation with IEC. This approach confers practical advantages over IEC, including analytical selectivity and workflow time efficiency.

Under the Age-Friendly Health System initiative, "What Matters" is defined as knowing the older adult's specific health outcome goals and care preferences. This involves multiple settings of care (e.g., hospital, skilled nursing facility, outpatient visits) and can include end-of-life care. However, the establishment of testing frequency criterion and the development of wide-scale diagnostic algorithms are often left undefined in older adults with poor prognosis and/or shortened life expectancy. Thus, multidisciplinary development of Geriatric 5M-informed optimization plans at the institution level and quality improvement strategies within the laboratory community may further the successful implementation of age-friendly efforts. While patients, end-users, and systems can attribute to implementation barriers, the development of an evidence-base wherein laboratory expertise is directly associated with patient outcomes is vital. Thus, a concentrated, cooperative age-friendly approach centered on What Matters may present a sustainable strategy for early transformation. Future research centered on piloted interventions on the laboratory's role in older adult care and end of life diagnostic management is needed.

Since several years, sports authorities, including national anti-doping organisations and the World Anti-Doping Agency (WADA) have published that the consumption of food supplements can be at risk for athletes due to potential contamination by prohibited substances. Despite these warnings, supplements are largely used by elite athletes and doping violations involving supplements are weekly reported in the media. Anabolic steroids, selective androgen receptor modulators (SARMs), metabolic modulators, stimulants and diuretics are among the most frequently detected substances in contaminated supplements. The author was involved in 2 cases where trimetazidine was identified as the source of the doping violation but the sport authorities sentenced both athletes. Case 1: trimetazidine in urine at 0.1 ng/mL; trimetazidine negative in 3 × 2 cm hair segments (LOQ at 1 ng/g [pg/mg]); trimetazidine at 4 ng/tablet in the supplement. Case 2: trimetazidine in urine at 0.1 and 1.6 ng/mL on 2 occasions; trimetazidine negative in 6 × 1 cm hair segments (LOQ at 1 ng/g [pg/mg]); trimetazidine at 7.2 μg/tablet in the supplement. Despite all pharmacological parameters were consistent with minute amounts of trimetazidine intake during a scenario of proven contamination, the presence of trimetazidine in the urine samples was recognized as an anti-doping rule violation and the athletes were sanctioned with a period of ineligibility of 6 months. From a forensic perspective, contamination is not doping. To avoid these conflicting issues with contaminations, the debate should move to the interest of using hair test results and the need of implementing a threshold for reporting the presence of a drug in urine at very low concentration.

Objectives: The diagnostic accuracy of presepsin (P-SEP) in the newborn is still under evaluation.

Methods: In a multicenter study, we studied the accuracy of P-SEP as a diagnostic marker of late-onset sepsis (LOS) in critical newborns with underlying disorders, to define the most accurate cut-off to distinguish infected from uninfected patients.

Results: Sixty-nine/351 newborns without infections at admission developed LOS. The median P-SEP value at T0 (admission) was 518.0 ng/L (IQR 313.0-789.0), without significant differences related to underlying diseases (p=0.52). In neonates who developed LOS, P-SEP increased at the onset of infection (T1) (median: 816.0 ng/L) and after 24-48 h (median: 901.0 ng/L) compared with their value at admission (median: 560.0 ng/L) (p<0.01 and p=0.03, respectively). The area under the ROC curve at T1 was 0.71 (95 % CI 0.65-0.78) when all cases of sepsis were included in the analysis and increased to 0.74 (95 % CI 0.66-0.81) considering only confirmed sepsis. Approximately two-thirds of patients were correctly classified, setting the cut-off at 713 ng/L, with a negative predictive value of 89.0 %.

Conclusions: At a cut-off of 713 ng/L, P-SEP has good accuracy in diagnosing LOS in critically ill newborns. In uninfected newborns, the median value of P-SEP is not influenced by any underlying pathology.

Objectives: Diagnosing monoclonal gammopathy in chronic kidney disease (CKD) patients is challenging due to the complex interpretation of serum free light chain (FLC) levels. This study aimed to assess the FLC levels in a large cohort of Chinese CKD patients.

Methods: We enrolled 5,287 patients with all-cause nondialysis CKD from three medical centers between February 2018 and April 2023. Central 95 % reference ranges were established using data from one center and validated in an independent subpopulation from the other two centers. The crude prevalence of light chain monoclonal gammopathy of undetermined significance (LC-MGUS) was assessed against established norms for the entire cohort and subgroups based on estimated glomerular filtration rate (eGFR).

Results: A notable proportion of patients exceeded the standard reference limits for kappa (89.0 %), lambda (72.1 %), and FLC ratio (10.5 %), whereas non-eGFR-based renal reference interval identified only 0.3 % with abnormal FLC ratios. The iStopMM reference ranges showed higher out-of-range rates for absolute FLC levels in patients with preserved kidney function and lower rates in those with impaired kidney function, while the FLC ratio references remained robust across all groups. The crude prevalence of LC-MGUS was 10.4 % using standard ranges, predominantly kappa LC-MGUS (99.8 %). This prevalence decreased to 0.3 % with non-eGFR-based renal reference interval and 0.5 % with the iStopMM ranges. Using the newly established reference ranges, the crude prevalence was found to be 0.9 %.

Conclusions: Our findings suggest that current FLC reference ranges are inadequate for the Chinese population, underscoring the need for eGFR-based reference ranges tailored to this demographic.