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  • Review Article2022-09-01 Diagnostic Hematology

    Unreliable Automated Complete Blood Count Results: Causes, Recognition, and Resolution

    Gene Gulati, Ph.D., Guldeep Uppal, M.D., and Jerald Gong, M.D.

    Ann Lab Med 2022; 42(5): 515-530

    Abstract : Automated hematology analyzers generate accurate complete blood counts (CBC) results on nearly all specimens. However, every laboratory encounters, at times, some specimens that yield no or inaccurate result(s) for one or more CBC parameters even when the analyzer is functioning properly and the manufacturer’s instructions are followed to the letter. Inaccurate results, which may adversely affect patient care, are clinically unreliable and require the attention of laboratory professionals. Laboratory professionals must recognize unreliable results, determine the possible cause(s), and be acquainted with the ways to obtain reliable results on such specimens. We present a concise overview of the known causes of unreliable automated CBC results, ways to recognize them, and means commonly utilized to obtain reliable results. Some examples of unreliable automated CBC results are also illustrated. Pertinent analyzer-specific information can be found in the manufacturers’ operating manuals.

  • Original Article2022-11-01 Transfusion and Cell Therapy

    Natural Killer Cell Expansion and Cytotoxicity Differ Depending on the Culture Medium Used

    Seung Kwon Koh , B.S., Jeehun Park , Ph.D., Seong-Eun Kim , B.S., Yuree Lim , M.S., Minh-Trang Thi Phan , Ph.D., Jinho Kim , B.S., Ilwoong Hwang , M.D., Yong-Oon Ahn , Ph.D., Sue Shin , M.D., Junsang Doh , Ph.D., and Duck Cho , M.D.

    Ann Lab Med 2022; 42(6): 638-649

    Abstract : Background: Adoptive cell therapy using umbilical cord blood (UCB)-derived allogeneic natural killer (NK) cells has shown encouraging results. However, because of the insufficient availability of NK cells and limited UCB volume, more effective culture methods are required. NK cell expansion and functionality are largely affected by the culture medium. While human serum is a major affecting component in culture media, the way it regulates NK cell functionality remains elusive. We elucidated the effects of different culture media and human serum supplementation on UCB NK cell expansion and functionality. Methods: UCB NK cells were cultured under stimulation with K562-OX40L-mbIL-18/21 feeder cells and IL-2 and IL-15 in serum-containing and serum-free culture media. The effects of the culture media and human serum supplementation on NK cell expansion and cytotoxicity were evaluated by analyzing the expansion rate, activating and inhibitory receptor levels, and the cytotoxicity of the UCB NK cells. Results: The optimal medium for NK cell expansion was Dulbecco’s modified Eagle’s medium/Ham’s F12 with supplements and that for cytotoxicity was AIM V supplemented with Immune Cell Serum Replacement. Shifting media is an advantageous strategy for obtaining several highly functional UCB NK cells. Live cell imaging and killing time measurement revealed that human serum enhanced NK cell proliferation but delayed target recognition, resulting in reduced cytotoxicity. Conclusions: Culture medium supplementation with human serum strongly affects UCB NK cell expansion and functionality. Thus, culture media should be carefully selected to ensure both NK cell quantity and quality for adoptive cell therapy.

  • 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 Microbiology

    Serotype Distribution and Antimicrobial Resistance of Streptococcus pneumoniae Causing Invasive Pneumococcal Disease in Korea Between 2017 and 2019 After Introduction of the 13-Valent Pneumococcal Conjugate Vaccine

    Gyu Ri Kim , Ph.D., Eun-Young Kim , Ph.D., Si Hyun Kim , Ph.D., Hae Kyung Lee , M.D., Jaehyeon Lee , M.D., Jong Hee Shin , M.D., Young Ree Kim , M.D., Sae Am Song , M.D., Joseph Jeong , M.D., Young Uh , M.D., Yu Kyung Kim , M.D., Dongeun Yong , M.D., Hyun Soo Kim , M.D., Sunjoo Kim , M.D., Young Ah Kim , M.D., Kyeong Seob Shin , M.D., Seok Hoon Jeong , M.D., Namhee Ryoo , M.D., and Jeong Hwan Shin , M.D.

    Ann Lab Med 2023; 43(1): 45-54

    Abstract : Background: Streptococcus pneumoniae is a serious pathogen causing various infections in humans. We evaluated the serotype distribution and antimicrobial resistance of S. pneumoniae causing invasive pneumococcal disease (IPD) after introduction of pneumococcal conjugate vaccine (PCV)13 in Korea and investigated the epidemiological characteristics of multidrug-resistant (MDR) isolates. Methods: S. pneumoniae isolates causing IPD were collected from 16 hospitals in Korea between 2017 and 2019. Serotyping was performed using modified sequential multiplex PCR and the Quellung reaction. Antimicrobial susceptibility tests were performed using the broth microdilution method. Multilocus sequence typing was performed on MDR isolates for epidemiological investigations. Results: Among the 411 S. pneumoniae isolates analyzed, the most prevalent serotype was 3 (12.2%), followed by 10A (9.5%), 34 (7.3%), 19A (6.8%), 23A (6.3%), 22F (6.1%), 35B (5.8%), 11A (5.1%), and others (40.9%). The coverage rates of PCV7, PCV10, PCV13, and pneumococcal polysaccharide vaccine (PPSV)23 were 7.8%, 7.8%, 28.7%, and 59.4%, respectively. Resistance rates to penicillin, ceftriaxone, erythromycin, and levofloxacin were 13.1%, 9.2%, 80.3%, and 4.1%, respectively. MDR isolates accounted for 23.4% of all isolates. Serotypes 23A, 11A, 19A, and 15B accounted for the highest proportions of total isolates at 18.8%, 16.7%, 14.6%, and 8.3%, respectively. Sequence type (ST)166 (43.8%) and ST320 (12.5%) were common among MDR isolates. Conclusions: Non-PCV13 serotypes are increasing among invasive S. pneumoniae strains causing IPD. Differences in antimicrobial resistance were found according to the specific serotype. Continuous monitoring of serotypes and antimicrobial resistance is necessary for the appropriate management of S. pneumoniae infections.

  • 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.

  • 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.

  • Guideline2022-07-01 Clinical Microbiology

    Update of Guidelines for Laboratory Diagnosis of COVID-19 in Korea

    Ki Ho Hong , M.D., Gab Jung Kim , Ph.D., Kyoung Ho Roh , M.D., Heungsup Sung , M.D., Jaehyeon Lee , M.D., So Yeon Kim , M.D., Taek Soo Kim , M.D., Jae-Sun Park , Ph.D., Hee Jae Huh , M.D., Younhee Park , M.D., Jae-Seok Kim , M.D., Hyun Soo Kim , M.D., Moon-Woo Seong , M.D., Nam Hee Ryoo , M.D., Sang Hoon Song , M.D., Hyukmin Lee , M.D., Gye Cheol Kwon , M.D., and Cheon Kwon Yoo , Ph.D.

    Ann Lab Med 2022; 42(4): 391-397

    Abstract : Korean Society for Laboratory Medicine and the Korea Disease Prevention and Control Agency have announced guidelines for diagnosing coronavirus disease (COVID-19) in clinical laboratories in Korea. With the ongoing pandemic, we propose an update of the previous guidelines based on new scientific data. This update includes recommendations for tests that were not included in the previous guidelines, including the rapid molecular test, antigen test, antibody test, and self-collected specimens, and a revision of the previous recommendations. This update will aid clinical laboratories in performing laboratory tests for diagnosing COVID-19.

  • 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.

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Annals of Laboratory Medicine
Journal Information September, 2024
Vol.44 No.5
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