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  • Review Article2022-09-01 Clinical Chemistry

    Review of the Use of Liquid Chromatography-Tandem Mass Spectrometry in Clinical Laboratories: Part II–Operations

    Brian A. Rappold , B.S.

    Ann Lab Med 2022; 42(5): 531-557

    Abstract : Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is increasingly utilized in clinical laboratories because it has advantages in terms of specificity and sensitivity over other analytical technologies. These advantages come with additional responsibilities and challenges given that many assays and platforms are not provided to laboratories as a single kit or device. The skills, staff, and assays used in LC-MS/MS are internally developed by the laboratory, with relatively few exceptions. Hence, a laboratory that deploys LC-MS/MS assays must be conscientious of the practices and procedures adopted to overcome the challenges associated with the technology. This review discusses the post-development landscape of LC-MS/MS assays, including validation, quality assurance, operations, and troubleshooting. The content knowledge of LC-MS/MS users is quite broad and deep and spans multiple scientific fields, including biology, clinical chemistry, chromatography, engineering, and MS. However, there are no formal academic programs or specific literature to train laboratory staff on the fundamentals of LC-MS/MS beyond the reports on method development. Therefore, depending on their experience level, some readers may be familiar with aspects of the laboratory practices described herein, while others may be not. This review endeavors to assemble aspects of LC-MS/MS operations in the clinical laboratory to provide a framework for the thoughtful development and execution of LC-MS/MS applications.

  • Review Article2023-01-01 Clinical Chemistry

    Calibration Practices in Clinical Mass Spectrometry: Review and Recommendations

    Wan Ling Cheng , M.Sc., Corey Markus , M.Sc., Chun Yee Lim , Ph.D., Rui Zhen Tan , Ph.D., Sunil Kumar Sethi , MBBS., and Tze Ping Loh , MB.BCh.BAO.; for the IFCC Working Group on Method Evaluation Protocols

    Ann Lab Med 2023; 43(1): 5-18

    Abstract : Background: Calibration is a critical component for the reliability, accuracy, and precision of mass spectrometry measurements. Optimal practice in the construction, evaluation, and implementation of a new calibration curve is often underappreciated. This systematic review examined how calibration practices are applied to liquid chromatography-tandem mass spectrometry measurement procedures. Methods: The electronic database PubMed was searched from the date of database inception to April 1, 2022. The search terms used were “calibration,” “mass spectrometry,” and “regression.” Twenty-one articles were identified and included in this review, following evaluation of the titles, abstracts, full text, and reference lists of the search results. Results: The use of matrix-matched calibrators and stable isotope-labeled internal standards helps to mitigate the impact of matrix effects. A higher number of calibration standards or replicate measurements improves the mapping of the detector response and hence the accuracy and precision of the regression model. Constructing a calibration curve with each analytical batch recharacterizes the instrument detector but does not reduce the actual variability. The analytical response and measurand concentrations should be considered when constructing a calibration curve, along with subsequent use of quality controls to confirm assay performance. It is important to assess the linearity of the calibration curve by using actual experimental data and appropriate statistics. The heteroscedasticity of the calibration data should be investigated, and appropriate weighting should be applied during regression modeling. Conclusions: This review provides an outline and guidance for optimal calibration practices in clinical mass spectrometry laboratories.

  • Review Article2023-05-01 Clinical Chemistry

    Biomarkers in Heart Failure: From Research to Clinical Practice

    Alexander E. Berezin , M.D., Ph.D. and Alexander A. Berezin , M.D.

    Ann Lab Med 2023; 43(3): 225-236

    Abstract : The aim of this narrative review is to summarize contemporary evidence on the use of circulating cardiac biomarkers of heart failure (HF) and to identify a promising biomarker model for clinical use in personalized point-of-care HF management. We discuss the reported biomarkers of HF classified into clusters, including myocardial stretch and biomechanical stress; cardiac myocyte injury; systemic, adipocyte tissue, and microvascular inflammation; cardiac fibrosis and matrix remodeling; neurohumoral activation and oxidative stress; impaired endothelial function and integrity; and renal and skeletal muscle dysfunction. We focus on the benefits and drawbacks of biomarker-guided assistance in daily clinical management of patients with HF. In addition, we provide clear information on the role of alternative biomarkers and future directions with the aim of improving the predictive ability and reproducibility of multiple biomarker models and advancing genomic, transcriptomic, proteomic, and metabolomic evaluations.

  • Original Article2023-01-01 Clinical Chemistry

    Intuitive Modification of the Friedewald Formula for Calculation of LDL-Cholesterol

    Jinyoung Hong , M.D., Hyunjung Gu , M.D., Juhee Lee , M.T., Woochang Lee , M.D., Sail Chun , M.D., Ki Hoon Han , M.D., and Won-Ki Min , M.D.

    Ann Lab Med 2023; 43(1): 29-37

    Abstract : Background: High LDL-cholesterol (LDL-C) is an established risk factor for cardiovascular disease and is considered an important therapeutic target. It can be measured directly or calculated from the results of other lipid tests. The Friedewald formula is the most widely used formula for calculating LDL-C. We modified the Friedewald formula for a more accurate and practical estimation of LDL-C. Methods: Datasets, including measured triglyceride, total cholesterol, HDL-cholesterol, and LDL-C concentrations were collected and assigned to derivation and validation sets. The datasets were further divided into five groups based on triglyceride concentrations. In the modified formula, LDL-C was defined as total cholesterol − HDL-cholesterol − (triglyceride/adjustment factor). For each group, the adjustment factor that minimized the difference between measured LDL-C and calculated LDL-C using modified formula was obtained. For validation, measured LDL-C and LDL-C calculated using the modified formula (LDL-CM), Friedewald formula (LDL-CF), Martin-Hopkins formula (LDL-CMa), and Sampson formula (LDL-CS) were compared. Results: In the derivation set, the adjustment factors were 4.7, 5.9, 6.3, and 6.4 for the groups with triglyceride concentrations 300 mg/dL, respectively. In the validation set, the coefficient of determination (R2) between measured and calculated LDL-C was higher for LDL-CM than for LDL-CF (R2=0.9330 vs. 0.9206). The agreement according to the National Cholesterol Education Program Adult Treatment Panel III classification of LDL-C was 86.36%, 86.08%, 86.82%, and 86.15% for LDL-CM, LDL-CF, LDL-CMa, and LDL-CS, respectively. Conclusions: We proposed a practical, improved LDL-C calculation formula by applying different factors depending on the triglyceride concentration.

  • Original Article2022-07-01 Clinical Chemistry

    Prognostic Utility of Procalcitonin, Presepsin, and the VACO Index for Predicting 30-day Mortality in Hospitalized COVID-19 Patients

    Mikyoung Park , M.D., Ph.D, Mina Hur , M.D., Ph.D, Hanah Kim , M.D., Ph.D, Chae Hoon Lee , M.D., Ph.D, Jong Ho Lee , M.D., Hyung Woo Kim , M.D., and Minjeong Nam , M.D., Ph.D.

    Ann Lab Med 2022; 42(4): 406-414

    Abstract : Background: Biomarkers and clinical indices have been investigated for predicting mortality in patients with coronavirus disease (COVID-19). We explored the prognostic utility of procalcitonin (PCT), presepsin, and the Veterans Health Administration COVID-19 (VACO) index for predicting 30-day-mortality in COVID-19 patients. Methods: In total, 54 hospitalized COVID-19 patients were enrolled. PCT and presepsin levels were measured using the Elecsys BRAHMS PCT assay (Roche Diagnostics GmbH, Mannheim, Germany) and HISCL Presepsin assay (Sysmex, Kobe, Japan), respectively. The VACO index was calculated based on age, sex, and comorbidities. PCT and presepsin levels and the VACO index were compared using ROC curve, Kaplan–Meier method, and reclassification analysis for the 30-day mortality. Results: ROC curve analysis was used to measure PCT and presepsin levels and the VACO index to predict 30-day mortality; the optimal cut-off values were 0.138 ng/mL for PCT, 717 pg/mL for presepsin, and 12.1% for the VACO index. On Kaplan–Meier survival analysis, hazard ratios (95% confidence interval) were 15.9 (4.1-61.3) for PCT, 26.3 (6.4-108.0) for presepsin, and 6.0 (1.7-21.1) for the VACO index. On reclassification analysis, PCT and presepsin in addition to the VACO index significantly improved the prognostic value of the index. Conclusions: This study demonstrated the prognostic utility of measuring PCT and presepsin levels and the VACO index in COVID-19 patients. The biomarkers in addition to the clinical index were more useful than the index alone for predicting clinical outcomes in COVID-19 patients.

  • Original Article2022-07-01 Clinical Chemistry

    Sex-Specific U-Shaped Relationships Between High-Density Lipoprotein Cholesterol Levels and 10-year Major Adverse Cardiovascular Events: A Nationwide Cohort Study of 5.7 Million South Koreans

    Hyun Suk Yang , M.D., Ph.D., Ho Jin Jeong , M.S., Hyeongsu Kim , M.D., Ph.D., Hweung Kon Hwang , M.D., Ph.D., Mina Hur , M.D., Ph.D., and Seungho Lee , Ph.D.

    Ann Lab Med 2022; 42(4): 415-427

    Abstract : Background: High-density lipoprotein cholesterol (HDL-C) is a well-known predictor of atherosclerotic cardiovascular diseases (ASCVD). We explored the relationships between HDL-C levels and 10-year major adverse cardiovascular events (MACE) and provided sex-specific upper reference limits for HDL-C levels. Methods: Based on the Korean National Health Insurance Sharing Service, we identified 5,703,897 subjects (women, 48%) with age ≥40 years, eligible HDL-C results, and no prior ASCVD in 2009. We investigated the distribution of 10-year MACE according to HDL-C levels in 10 mg/dL (0.26 mmol/L) intervals and in three HDL-C groups (low: men

  • Review Article2024-01-01 Clinical Chemistry

    Bias in Laboratory Medicine: The Dark Side of the Moon

    Abdurrahman Coskun , M.D.

    Ann Lab Med 2024; 44(1): 6-20

    Abstract : Physicians increasingly use laboratory-produced information for disease diagnosis, patient monitoring, treatment planning, and evaluations of treatment effectiveness. Bias is the systematic deviation of laboratory test results from the actual value, which can cause misdiagnosis or misestimation of disease prognosis and increase healthcare costs. Properly estimating and treating bias can help to reduce laboratory errors, improve patient safety, and considerably reduce healthcare costs. A bias that is statistically and medically significant should be eliminated or corrected. In this review, the theoretical aspects of bias based on metrological, statistical, laboratory, and biological variation principles are discussed. These principles are then applied to laboratory and diagnostic medicine for practical use from clinical perspectives.

  • Review Article2023-09-01 Clinical Chemistry

    Artificial Intelligence in Point-of-Care Testing

    Adil I. Khan , M.Sc., Ph.D., Mazeeya Khan , M.Sc., and Raheeb Khan , B.Sc.

    Ann Lab Med 2023; 43(5): 401-407

    Abstract : With the projected increase in the global population, current healthcare delivery models will face severe challenges. Rural and remote areas, whether in developed or developing countries, are characterized by the same challenges: the unavailability of hospitals, lack of trained and skilled staff performing tests, and poor compliance with quality assurance protocols. Point-of-care testing using artificial intelligence (AI) is poised to be able to address these challenges. In this review, we highlight some key areas of application of AI in point-of-care testing, including lateral flow immunoassays, bright-field microscopy, and hematology, demonstrating this rapidly expanding field of laboratory medicine.

  • Original Article2022-11-01 Clinical Chemistry

    Age Group-specific Reference Intervals for the Elecsys Anti-Müllerian Hormone Assay in Healthy Korean Women: a Nationwide Population-based Study

    Misuk Ji , M.D., Ph.D., Kwang-Rae Kim , M.D., Ph.D., Hyun-Ki Kim , M.D., Woochang Lee , M.D., Ph.D., Yeo-Min Yun , M.D., Ph.D., Sail Chun , M.D., Ph.D., and Won-Ki Min , M.D., Ph.D.

    Ann Lab Med 2022; 42(6): 621-629

    Abstract : Background: Anti-Müllerian hormone (AMH) is one of the most reliable markers of ovarian reserve. Automated AMH assays are widely used in clinical laboratories, but reference intervals for the Elecsys AMH assay for Asian populations have not yet been determined. We aimed to determine reference intervals in healthy Korean women. Methods: The study included 1,450 women aged 19 to 54 years who participated in the Korea National Health and Nutrition Examination Survey between 2013 and 2016. The study participants were divided into seven 5-year age groups. AMH and progesterone concentrations were measured using Roche Elecsys assays, and bone morphogenetic protein-15 (BMP15) was genotyped for the detection of major variants. Age group-specific reference intervals for AMH were established as recommended by the CLSI EP28-A3c guidelines. Results: The mean age was 37.4 years. AMH concentrations decreased with increasing age, especially after 40 years, with the median AMH decreasing from 30.9 pmol/L in participants of 19–24 years to 0.071 pmol/L in participants of 50–54 years. The mid-95 percentile AMH reference intervals decreased from 7.93–81.21 pmol/L in participants of 19–24 years to 0.07–3.86 pmol/L in participants of 50–54 years. Disease-associated BMP15 variants were not detected. Conclusions: We determined Elecsys AMH assay reference intervals in healthy Korean women. The results may provide basic information for the interpretation of AMH concentrations and assessment of ovarian reserve in Korean women.

  • Original Article2022-05-01 Clinical Chemistry

    Effect of Outlier Elimination on the 99th Percentile Upper Reference Limits of High-Sensitivity Cardiac Troponin I Assays Based on a Strictly Selected Healthy Reference Population

    Sunyoung Ahn , Ph.D., Hyun-Ki Kim , M.D., Woochang Lee , Ph.D., Sail Chun , Ph.D., and Won-Ki Min , Ph.D.

    Ann Lab Med 2022; 42(3): 331-341

    Abstract : Background: We established high-sensitivity cardiac troponin I (hsTnI) 99th percentile upper reference limits (URLs) for the Centaur XPT High-Sensitivity Troponin I assay (Centaur hsTnI; Siemens, Erlangen, Germany) and Atellica IM High-Sensitivity Troponin I assay (Atellica hsTnI; Siemens) and assessed the effect of outlier elimination. Methods: The reference population comprised 380 men and 387 women, satisfying the strict systematic reference population criteria. After reference population verification by the N-terminal pro-B-type natriuretic peptide (NT-proBNP) assay, 99th percentile URLs for Centaur hsTnI and Atellica hsTnI were calculated before and after outlier elimination. Results: The 99th percentile URL for Centaur hsTnI was 60.4 (men, 74.7; women, 57.5) ng/L and that for Atellica hsTnI was 59.6 (men, 75.2; women, 55.1) ng/L. After the elimination of 61 (8.0%) outlier samples in Centaur hsTnI and 58 (7.6%) in Atellica hsTnI, the 99th percentile URLs were 13.5 ng/L (men, 15.3 ng/L; women, 11.9 ng/L) and 13.4 ng/L (men, 15.5 ng/L; women, 12.9 ng/L), respectively, significantly lower than those before outlier elimination. The CVs at the 99th percentile URLs were 5.2% and 3.5%, respectively. The measurable fractions among the reference population were 91.5% and 93.4%, respectively. Performance evaluation of Atellica B-type natriuretic peptide (BNP), Atellica NT-proBNP, Centaur hsTnI, and Atellica hsTnI showed outstanding results. Conclusions: The Korean hsTnI 99th percentile URLs calculated in this study were significantly lower after outlier elimination than before. Centaur hsTnI and Atellica hsTnI meet the “Guideline acceptable” and “Level 3 (second generation, high sensitivity)” requirements, satisfying international standards.

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Annals of Laboratory Medicine
Journal Information May, 2024
Vol.44 No.3
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