Clinical chemistry and laboratory medicine最新文献

Objectives: The adrenal glands are the main source of 11-oxygenated androgens (11-OAs), including the potent 11-ketotestosterone (11-KT) and the weaker metabolites 11β-hydroxyandrostenedione (11-OHA4), 11β-hydroxytestosterone (11-OHT) and 11-ketoandrostenedione (11-KA4). Due to their adrenal origin, 11-OAs allow the differentiation of adrenal and extra-adrenal-produced androgens. However, their clinical use is limited due to the lack of robust age- and sex-specific reference intervals (RIs).

Methods: To establish RIs from infancy throughout childhood and adulthood, we performed simultaneous quantification of 11-OHA4, 11-OHT, 11-KA4, 11-KT, and clinically relevant steroid hormones via LC-MS/MS. We analyzed 3,796 serum samples from 2,505 healthy individuals, aged 0.25-80 years, encompassing minipuberty and pubertal stages.

Results: 11-OA serum levels increase from infancy throughout childhood and adulthood, with the most pronounced increase during puberty. Significant sex differences were observed, and age-, sex-, and puberty-dependent RIs were established. In contrast to testosterone, 11-OAs exhibited a comparable pattern during the first year of life in both sexes. At 3 and 6 months of age - when testosterone levels were 100- and 10-fold higher, respectively, in males than in females - no correlation was observed between testosterone and the adrenal-derived androgens (11-OAs, A4, and DHEAS) in males.

Conclusions: Established age-, sex-, and puberty-dependent RIs support the clinical interpretation of 11-OA measurements in disorders characterized by androgen excess. The differences in the regulation of classical androgens and 11-OAs during minipuberty suggest that the transient increase in androgens during the first months of life is most likely due to activation of the hypothalamic-pituitary-gonadal axis.

Objectives: The acute coronary syndrome (ACS) is a leading cause of morbidity and mortality worldwide, with timely diagnosis being critical for improving outcomes. Since high-sensitivity cardiac troponin (hs-cTn) assays have become the gold standard for detecting myocardial injury, this study aimed to evaluate the analytical performance of the novel Roche Elecsys TnT hs Gen 6 (TNT6ST) immunoassay.

Methods: The TNT6ST immunoassay was assessed for intra- and inter-assay imprecision, linearity, limit of blank (LoB), limit of detection (LoD), functional sensitivity, and 99th percentile upper reference limit (URL). Comparisons were made with the previous Elecsys hs-cTnT immunoassay (TNTHSSTX). Hemolysis interference was evaluated in plasma samples with serially induced hemolysis.

Results: TNT6ST exhibited excellent precision (intra-assay CV 0.8-2.0 %, inter-assay 1.5-2.4 %), linearity (r=1.00), LoB of 0.939 ng/L, LoD of 1.201 ng/L, and functional sensitivity of 1.255 ng/L. The 99th percentile URL was 20.9 ng/L overall, 30.5 ng/L in males, and 13.7 ng/L in females. Comparison with TNTHSSTX showed strong correlation (r=0.995) but a systematic bias, with TNT6ST overestimating cTnT by around 66 %. Hemolysis decreased cTnT values in both assays, but TNT6ST remained within the allowable total error, while TNTHSSTX exceeded this threshold at higher hemolysis levels.

Conclusions: The novel Roche TNT6ST immunoassay demonstrates superior precision, sensitivity, and robustness to hemolysis compared with its predecessor, with excellent correlation across a wide cTnT range, supporting its reliability for introduction into routine clinical practice.

Lipoprotein(a) (Lp(a)) has the reputation of being the most misunderstood metric in laboratory medicine. The unique apolipoprotein(a) (apo(a)) in Lp(a) is very heterogenous, the kringle IV domain of apo(a) being formed by 12-50 kringles due to 3 to ∼40 KIV₂ repeats. The variable number of repeated identical KIV₂ domains causes KIV₂-dependent antibodies to form different amounts of immunocomplexes with apo(a), leading to higher recovery for larger and lower recovery for smaller apo(a) particles than the calibrator. Consequently, the required identity between the analyte in samples and in assay calibrator(s), which is at the basis of any immunoassay, cannot be accomplished in the case of Lp(a). Global Lp(a) standardization was first attempted in the nineties by an IFCC Working Group on Lp(a) Standardization using an ELISA-based reference measurement procedure (RMP) with monoclonal anti-apo(a) antibodies against unique epitopes. WHO-IFCC reference material (RM), named SRM2B, was established with apo(a) expressed in molar units. Currently, a 2nd generation, ISO 15193 compliant, IFCC-endorsed multiplex RMP based on quantitative Mass Spectrometry (MS) has been developed. Traceability to SRM2B is maintained using a value transfer protocol that assigned values to commutable serum-based secondary RMs. ISO 15194 compliant serum-based RMs are currently available. A network of three calibration laboratories runs the harmonized apo(a) RMP. Equipped with a state-of-the-art calibration hierarchy for Lp(a) and using a 2-step approach, it is prime time for global Lp(a) standardization to ensure effective implementation of Lp(a) clinical guidelines and refined cardiovascular precision diagnostics.

Objectives: Identifying individuals with vitamin B12 (B12) deficiency is challenging due to poor harmonization across total B12 assays. To establish clinically meaningful thresholds for the Roche assay, we characterized B12 concentrations associated with deficiency by comparing individuals with macrocytic anemia and other anemia subtypes or no anemia.

Methods: We retrospectively analysed 10 years of laboratory data from adults tested for total B12 and folate (Roche Cobas), homocysteine (Abbott Architect), and haematological parameters (Sysmex XE/XN). Individuals receiving vitamin supplementation or with isolated folate deficiency were excluded. Anemia subtypes (normocytic, microcytic, macrocytic) were classified using red blood cell count, hemoglobin concentration, and mean corpuscular volume relative to reference intervals.

Results: Among 5,147 subjects (median age 65 years; 25th-75th percentile: 49-77), 36.8 % had anemia. Total B12 concentrations decreased by 2.3 ng/L for each 1 μmol/L increase in homocysteine and by 6.8 ng/L per decade of age increase (p<0.0001). Macrocytic anemia (9.4 % of subjects), was associated with a mean reduction of 18.6 ng/L in B12 levels compared with no anemia and microcytic anemia. Mean homocysteine concentrations rose progressively, from 15.9 to 21.5 μmol/L and then to 34.9 μmol/L, as total B12 concentrations fell in the intervals: 342-447 ng/L, 341-258 ng/L, and 257 - <50 ng/L, respectively.

Conclusions: Among individuals investigated for anemia, macrocytosis, a hallmark of B12 depletion, supports that total B12 concentrations ≤257 ng/L measured using the Roche assay likely reflect severe deficiency. Levels between 258 and 341 ng/L may indicate early depletion and warrant confirmation through elevated homocysteine concentrations.

Objectives: The clinical utility of serum bone turnover markers (BTMs) in managing osteoporosis in the elderly is constrained by the absence of personalized reference intervals (prRI) based on biological variation (BV).

Methods: This longitudinal study tracked monthly serum levels of β-CTX, PINP, OC, PTH, and 25(OH)D over six months in 40 healthy elderly participants aged 60-75 years (16 males and 24 females). The study calculated estimates of within-subject BV (CV_I), between-subject BV (CV_G), within-person BV (CV_P), analytical variation (CV_A), and reference change values (RCVs).These parameters were subsequently used to establish the personalized reference interval (prRI).

Results: Considerable variability in CV_I, CV_P, and CV_G was observed for BTMs in older adults. Gender differences in baseline concentrations were observed for PINP, OC, and 25(OH)D (p<0.05), but no significant differences were found in BV parameters. Among the markers, OC exhibited the lowest CV_I (7.9 %), while β-CTX had the highest (14.8 %). Other markers had CV_I values ranging from 11.0 to 14.2 %. RCVs ranged from -19.8 to -33.7 % and 24.6 to 50.8 %. For all five BTMs, the CV_I-based prRI ranges were narrower than the popRI, whereas the CV_P-based prRIs showed wide inter-individual variation, reflecting substantial heterogeneity in prRIs among older adults.

Conclusions: This study establishes BV-based prRI for BTMs in older adults, which offers a more clinically relevant interpretation of individual-level data than popRI and facilitates more accurate clinical decision-making.

Objectives: This study presents a candidate reference measurement procedure (RMP) for testosterone quantification in human serum and plasma, utilizing isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC MS/MS).

Methods: The developed LC-MS/MS method employs a two-dimensional heart-cut LC approach combined with solid-phase extraction (SPE) for sample clean-up, ensuring accurate testosterone analysis in human serum and plasma. Traceability to SI units was achieved by using a primary reference material listed by the Joint Committee on Traceability in Laboratory Medicine (JCTLM). An alternative quantification approach using qNMR content determination is also described. Assay validation followed current guidelines, assessing selectivity and specificity with spiked serum samples. Matrix effects were evaluated through post-column infusion experiments and comparison of standard line slopes. Precision, accuracy, and trueness were determined through an extensive 5-day protocol. Measurement uncertainty for reference value assignment was evaluated as per the Guide to the Expression of Uncertainty in Measurement (GUM), with three individual sample preparations performed on at least two different days.

Results: The RMP facilitated testosterone quantification in the range of 27.7 pmol/L (8.00 pg/mL) to 62.4 nmol/L (18.0 ng/mL) without interference from structurally-related compounds or matrix effects. Intermediate precision was ≤3.1 % and repeatability ranged from 1.4 to 1.9 % across all analyte concentrations. The bias ranged from -1.2 to 3.0 % for all levels and matrices. Expanded measurement uncertainties (k=2) for single measurements (n=1) ranged from 3.4 to 6.4 %. Measurement uncertainties for target value assignment (n=6) were ≤1.5 %, with expanded uncertainties ≤2.9 % (k=2) for all levels. Specific assessment at the LLMI yielded an expanded uncertainty (k=2) of 4.4 % for target value assignments (n=6), confirming the method's suitability for accurate and precise quantification over the entire measuring range.

Conclusions: The RMP demonstrated high analytical performance for testosterone quantification in human serum and plasma, making it suitable for routine assay standardization and clinical sample evaluation.

Objectives: Clinical intent for laboratory testing ("indication") is rarely recorded in structured form, limiting contextual interpretation, auditability, and utilization stewardship. We developed a comprehensive, and clinically applicable framework that standardizes laboratory test indications and links them to indication-dependent utilization and interpretation.

Methods: A structured literature review on utilization, appropriateness, and request rationale informed an iterative, consensus-based process with a multidisciplinary expert panel to develop and operationalize an indication taxonomy and attribute schema. Structural coherence was assessed by comparing semantic distance hierarchies derived from indication labels alone with an enriched multi-layer ("layered prototype") representation incorporating these attributes. Use cases were applied to assess feasibility of indication-to-interpretation mapping.

Results: We defined 19 distinct indication types, grouped into five clusters across the clinical course: Initial Detection and Diagnostic Clarification, Disease Characterization and Prognosis, Therapy Guidance and Safety, Longitudinal Management and Reassessment, and Analytical and External Requirements. Each is specified with structured attributes and examples to support implementation. Semantic distance analyses supported a coherent hierarchy. Layered prototypes yielded more informative organization than labels alone, enabling context-dependent consolidation and guided deployment.

Conclusions: By providing explicit indication-to-interpretation mapping/logic, the framework closes a key gap in the total testing process between order entry and post-analytical interpretation. It supports context-specific decision limits, reporting logic, and stewardship analytics, and is amenable to formalization as a machine-readable ontology for interoperable implementation.