Letter to the Editor2022-03-01 Diagnostic Immunology
Sang-Hyon Kim 
, M.D., Ph.D., Ji-Hyun Lee , M.S., Hye-Jin Jeong , M.D., Ji-Min Kim , M.D., Ph.D., Won-Ki Baek , M.D., Ph.D., Tae-Hwan Kim , M.D., Ph.D., Jae-Bum Jun , M.D., Ph.D., and Chang-Nam Son , M.D., Ph.D.
Original Article2022-11-01 Clinical Chemistry
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.
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
Sunyoung Ahn , Ph.D., Hyun-Ki Kim , M.D., Woochang Lee , Ph.D., Sail Chun , Ph.D., and Won-Ki Min , Ph.D.
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.
Guideline2023-03-01 Clinical Microbiology
Ki Ho Hong , M.D., Gab Jung Kim , Ph.D., Kyoung Ho Roh , M.D., Hyukmin Lee , M.D., Ok Kyu Park , M.S., Taek Soo Kim , M.D., Jae-Seok Kim , M.D., Jaehyeon Lee , M.D., Moon-Woo Seong , M.D., So Yeon Kim , M.D., Jae-Sun Park , Ph.D., Younhee Park , M.D., Hee Jae Huh , M.D., Namhee Ryoo , M.D., Hyun Soo Kim , M.D., Heungsup Sung , M.D., and Cheon Kwon Yoo , Ph.D.; On behalf of the Committee of Management of Laboratory Tests for Infectious Diseases, Korean Society for Laboratory Medicine, and the Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency
Abstract : While the coronavirus disease 2019 pandemic is ongoing, monkeypox has been rapidly spreading in non-endemic countries since May 2022. Accurate and rapid laboratory tests are essential for identifying and controlling monkeypox. Korean Society for Laboratory Medicine and the Korea Disease Prevention and Control Agency have proposed guidelines for diagnosing monkeypox in clinical laboratories in Korea. These guidelines cover the type of tests, selection of specimens, collection of specimens, diagnostic methods, interpretation of test results, and biosafety. Molecular tests are recommended as confirmatory tests. Skin lesion specimens are recommended for testing in the symptomatic stage, and the collection of both blood and oropharyngeal swabs is recommended in the presymptomatic or prodromal stage.
Letter to the Editor2022-01-01 Diagnostic Immunology
Danilo Villalta , M.D., Anna Moratto , Ph.D., Valeria Salgarolo , Ph.D., Mirella Da Re , Ph.D., Roberto Giacomello , Ph.D., and Giacomo Malipiero , M.D.
Brief Communication2023-01-01 Diagnostic Immunology
Sumi Yoon , M.D., Ph.D., Yong Kwan Lim , M.D., Hye Ryoun Kim , M.D., Ph.D., Mi-Kyung Lee , M.D., Ph.D., and Oh Joo Kweon , M.D., Ph.D.
Abstract : Cytokeratin 19 fragment antigen 21-1 (CYFRA 21-1) is useful for predicting and monitoring non-small cell lung cancer prognosis. We established reference intervals (RIs) of CYFRA 21-1 in Korean adults, including those older than 60 years. Data of 4,098 apparently healthy subjects (age range, 20–87 years) were analyzed after excluding those with a history of malignancy, high tumor marker concentrations (except CYFRA 21-1), and/or abnormal findings on a chest computed tomography scan through medical chart review. After removing two outliers, RIs of CYFRA 21-1 were determined using data of 4,096 subjects based on the non-parametric method (2.5th and 97.5th percentiles) according to CLSI guidelines EP28-A3c. The subjects were divided into two and four groups according to sex and age (20–40, 41–50, 51–60, and >60 years), respectively, and the median CYFRA 21-1 concentration was compared between the groups. The RI of CYFRA 21-1 was 0.66–3.84 ng/mL, applicable to both men and women. Regardless of sex, the CYFRA 21-1 concentration increased with age, suggesting that age-dependent RIs of CYFRA 21-1 should be applied. Rather than using a single RI provided by the manufacturer, the RI of CYFRA 21-1 should be continually verified and established in each clinical laboratory.
Editorial2022-03-01
Young Jin Kim , M.D., Ph.D., Soo-Youn Lee , M.D., Ph.D., and Mina Hur , M.D., Ph.D.
Original Article2022-03-01 Clinical Chemistry
Youngwon Nam , M.D., Joon Hee Lee , M.D., Sung Min Kim , M.T., Sun-Hee Jun , M.T., Sang Hoon Song , M.D., Ph.D., Kyunghoon Lee , M.D., and Junghan Song , M.D., Ph.D.
Abstract : Background: Results from laboratories using multiple instruments should be standardized or harmonized and comparability-verified for consistent quality control. We developed a simple frequent comparability verification methodology applicable to large healthcare centers using multiple clinical chemistry instruments from different manufacturers. Methods: Comparability of five clinical chemistry instruments (Beckman Coulter AU5800, Abbott Architect Ci16000, two Siemens Vista 1500, and Ortho Vitros 5600) was evaluated from 2015 to 2019 for 12 clinical chemistry measurements. Pooled residual patient samples were used for weekly verifications. Results from any instrument exceeding the allowable verification range versus the results from the comparative instrument (AU5800) were reported to clinicians after being multiplied by conversion factors that were determined via a linear regression equation obtained from simplified comparison. Results: Over the five-year study period, 432 weekly inter-instrument comparability verification results were obtained. Approximately 58% of results were converted due to non-comparable verification. Expected average absolute percent bias and percentage of non-comparable results for non-converted and converted results after conversion action were much lower than those for data measured before conversion action. The inter-instrument CV for both non-converted and converted results after conversion action was much lower than that for measured data before conversion action for all analytes. Conclusions: We maintained within-laboratory comparability of clinical chemistry tests from multiple instruments for five years using frequent low-labor periodic comparability verification methods from pooled residual sera. This methodology is applicable to large testing facilities using multiple instruments.
Original Article2022-09-01 Diagnostic Hematology
Hyun-Young Kim , M.D., In Young Yoo , M.D., Dae Jin Lim , M.T., Hee-Jin Kim , M.D., Sun-Hee Kim , M.D., Sang Eun Yoon , M.D., Seok Jin Kim , M.D., Duck Cho , M.D., and Kihyun Kim , M.D.
Abstract : Background: Minimal residual disease (MRD) is an important prognostic factor for evaluating a deeper treatment response in patients with multiple myeloma (MM). We evaluated the clinical utility of next-generation flow (NGF)-based MRD assessment in a heterogeneous MM patient population. Methods: Patients with suspected morphological remission after or during MM treatment were prospectively enrolled. In total, 108 bone marrow samples from 90 patients were analyzed using NGF-based MRD assessment according to the EuroFlow protocol, and progression-free survival (PFS) was evaluated according to the International Myeloma Working Group response status, cytogenetic risk, and MRD status. Results: The overall MRD-positive rate was 31.5% (34/108 samples), and MRD-positive patients showed a lower PFS than MRD-negative patients (P=0.005). MRD-positive patients showed inferior PFS than MRD-negative in patients with stringent complete remission (sCR)/complete remission (P=0.014) and high-risk cytogenetic abnormalities (P=0.016). MRD was assessed twice in 18 patients with a median interval of 12 months. Sustained MRD negativity was only observed in patients with sustained sCR, and their PFS was superior to that of patients who were not MRD-negative (P=0.035). Conclusions: Clinical application of NGF-based MRD assessment can provide valuable information for predicting disease progression in patients with MM in remission, including those with high-risk cytogenetic abnormalities.
Original Article2022-07-01 Transfusion and Cell Therapy
Juhye Roh , M.D., Ph.D., Sinyoung Kim , M.D., Ph.D., June-Won Cheong , M.D., Ph.D., Su-Hee Jeon , M.S., Hyun-Kyung Kim , M.S., Moon Jung Kim , M.D., Ph.D., and Hyun Ok Kim , M.D., Ph.D.
Abstract : Background: Reagent red blood cells (RBCs) are prepared from donated whole blood, resulting in various combinations of blood group antigens. This inconsistency can be resolved by producing RBCs with uniform antigen expression. Induced pluripotent stem cells (iPSCs) generated directly from mature cells constitute an unlimited source for RBC production. We aimed to produce erythroid cells from iPSCs for diagnostic purposes. We hypothesized that cultured erythroid cells express surface antigens that can be recognized by blood group antibodies. Methods: iPSCs were co-cultured with OP9 stromal cells to stimulate differentiation into the erythroid lineage. Cell differentiation was examined using microscopy and flow cytometry. Hemoglobin electrophoresis and oxygen-binding capacity testing were performed to verify that the cultured erythroid cells functioned normally. The agglutination reactions of the cultured erythroid cells to antibodies were investigated to confirm that the cells expressed blood group antigens. Results: The generated iPSCs showed stemness characteristics and could differentiate into the erythroid lineage. As differentiation progressed, the proportion of nucleated RBCs increased. Hemoglobin electrophoresis revealed a sharp peak in the hemoglobin F region. The oxygen-binding capacity test results were similar between normal RBCs and cultured nucleated RBCs. ABO and Rh-Hr blood grouping confirmed similar antigen expression between the donor RBCs and cultured nucleated RBCs. Conclusions: We generated blood group antigen-expressing nucleated RBCs from iPSCs co-cultured with OP9 cells that can be used for diagnostic purposes. iPSCs from rare blood group donors could serve as an unlimited source for reagent production.
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