Hyung-Doo Park

The Academy of Fabry Disease in the Korean Society of Nephrology has developed evidence-based clinical practice guidelines to optimize the management and treatment of Fabry nephropathy. Although Fabry disease is a rare genetic disorder, the recent availability of effective therapeutic options, including enzyme replacement therapy and chaperone therapy, highlights the importance of early diagnosis and timely intervention. These guidelines were developed using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology, with support from methodology experts. Clinical recommendations were derived through a systematic literature review addressing 11 key questions. These guidelines are intended to assist healthcare professionals, including nephrologists, in making informed, evidence-based clinical decisions to improve patient outcomes.

Sung-Eun Cho, M.D., Jungsun Han, M.S., Rihwa Choi, M.D., Sang Gon Lee, M.D., Hyung-Doo Park, M.D.. Lab Med Online 2026;16:357-68. https://doi.org/10.47429/lmo.2026.16.4.357

A case of analytical interference in urine immunofixation electrophoresis (IFE) caused by daratumumab is presented. Daratumumab, an IgG1-kappa monoclonal antibody, is well-known to produce a false IgG-kappa band in serum IFE, but urinary interference has not been reported because intact IgG is generally not filtered through the glomerulus. A 67-year-old man presented with nephrotic syndrome and was found to have markedly elevated serum creatinine (3.10 mg/dL), free kappa light chains (453.42 mg/dL) and kappa/lambda ratio (23.23). Baseline serum and urine electrophoresis and IFE showed no monoclonal protein (M-protein), while bone marrow examination confirmed light chain deposition disease with kappa restriction. Following two cycles of daratumumab-based chemotherapy, new IgG-kappa bands appeared in both serum and urine IFE despite improving free light chain levels and unremarkable protein electrophoretic patterns. Suspecting therapeutic antibody interference, the HYDRASHIFT 2/4 Daratumumab assay (HYDRASHIFT assay) was applied to both serum and concentrated urine samples. The IgG-kappa bands in both serum and urine IFE disappeared and exhibited a cathodal shift, confirming that they represented daratumumab rather than endogenous M-protein. This case demonstrates that daratumumab may become detectable in urine in the setting of severely impaired glomerular permeability and highlights that the HYDRASHIFT assay can be effectively applied to urine to resolve analytical interference. Awareness of this phenomenon is important for the accurate interpretation of urine IFE results in patients receiving daratumumab.

Se-Eun Koo, M.D., Soo-Ho Yu, M.D., Hyun-Woo Lee, M.D., Gyujin Lim, M.D., Hyung-Doo Park, M.D., Ph.D., and Soo-Youn Lee, M.D., Ph.D.. Ann Lab Med -0001;0:. https://doi.org/10.3343/alm.2026.0262

Background/Objectives: Glycated hemoglobin (HbA1c) is widely used to monitor glycemic control, but the accuracy and flag detection rates of HbA1c assays can vary in the presence of Hb variants such as Hb G-Coushatta (Coushatta) and Hb Queens (Queens), which are common in the Korean population. Methods: We evaluated four HbA1c platforms—Arkray ADAMS HA-8190V (HA-8190V) fast/variant modes; Tosoh HLC-723 G11 (G11) standard/variant modes; Bio-Rad D-100 (D-100); Sebia Capillarys 2 Flex Piercing (Capillarys)—using 33 Hb variant samples (26 Coushatta, 7 Queens). The Roche Tina-quant HbA1c Gen. 3 immunoassay was used as the comparative method. With UPLC-MS/MS used as the reference for variant identification, analytical performance was assessed by calculating mean % differences in HbA1c and evaluating Hb variant flag detection rates. Results: The mean % differences in HbA1c compared to the comparative method were −1.5% and −0.9% for Coushatta and Queens, respectively, with HA-8190V variant mode; −28.4% and −17.6% with HA-8190V fast mode; +33.5% and +2.2% with the G11 variant mode; −28.1% and −14.3% with G11 standard mode; −5.9% and −3.2% with D-100; and +1.0% and −6.2% with Capillarys. For flag detection, rates were 100% and 0% with HA-8190V fast mode; 84.6% and 28.6% with G11 standard mode; and 100% and 100% with all other platforms. Conclusions: Coushatta caused severe underestimation in rapid modes, while Queens hindered automated detection. While variant modes significantly improved detection, they showed platform-dependent accuracy. When Hb variant status is unknown, use of the variant mode is recommended to ensure reliable results.

Controlling pre-analytical factors ensures the accuracy of hormone and tumor marker assays. We evaluated the combined effects of using different serum separator tubes (i.e., Ampulab [Soyagreentec]), Vacutainer [Becton Dickinson], and Vacuette [Greiner Bio-One]) and transport methods (i.e., the AirLab high-speed pneumatic tube system [PTS; PazKorea] and a conveyor system) on measurement results of 20 analytes. Blood was collected from 57 volunteers and equally distributed into six tubes per participant to cover all possible tube type-transport system combinations. Twenty analytes were measured using Cobas e801 (Roche Diagnostics) and UniCel DXI 800 (Beckman Coulter) analyzers. For each analyte, the same analyzer was used across all samples. To evaluate hemolysis in PTS-transported samples, hemolytic index, AST, potassium, and lactate dehydrogenase levels were measured using Cobas c702 (Roche Diagnostics). Clinically significant or important differences were defined as average percentage biases exceeding European Federation of Clinical Chemistry and Laboratory Medicine desirable and optimal bias criteria, respectively. Estradiol showed a clinically significant difference (-8.21%) in conveyor-transported Vacutainer versus Vacuette tubes and clinically important difference between Ampulab and other tubes as separator gel adsorption was different. Insulin exhibited a clinically important negative bias (-6.83%) in PTS-transported Vacuette tubes owing to insulin-degrading enzyme release from hemolyzed erythrocytes. No other analytes exhibited clinically significant or important differences. Vacuette tubes were the most susceptible to PTS-induced hemolysis, corresponding to the largest insulin bias. Ampulab tubes and the AirLab system performed comparably to their comparators, though caution is warranted for estradiol and insulin results.

Background: Pneumatic tube systems (PTSs) have revolutionized sample transport efficiency, yet concerns about sample integrity remain unresolved. This study evaluated the AirLab system (PazKorea, Hanam-si, Korea), a novel high-speed carrier-free PTS, for its impact on sample integrity and turnaround time (TAT) under controlled pre-analytical conditions. Methods: Blood specimens were collected in duplicate from 42 participants (30 healthy volunteers and 12 outpatients with chronic alcohol use) and randomly assigned to PTS or manual transport. Multiple laboratory parameters were analysed, including chemistry, hematology, coagulation, and heavy metal tests. Sample integrity was assessed by comparing test results between transport methods using both statistical analysis and clinical significance criteria based on total allowable error (TAE). Pre-analytical, analytical and total TATs were compared between transport methods. Results: Among 20 measurands, four showed statistically significant differences: glucose, potassium (K), lactate dehydrogenase (LD), and mean corpuscular volume (MCV). PTS yielded higher results for glucose, K and LD (average percentage biases: 1.88%, 2.01%, and 15.80%, respectively), while producing lower results for MCV (average percentage bias: −0.47%). Only LD showed clinically significant differences, as its average percentage bias exceeded its desirable TAE. PTS significantly reduced both pre-analytical and total TATs for all test types, with reductions ranging from 12.12% to 22.82% and 7.32% to 8.98%, respectively, whereas analytical TATs remained unchanged. Conclusions: The AirLab system effectively preserves sample integrity for most laboratory parameters while improving operational efficiency through TAT reduction. However, the clinically significant elevation in LD levels necessitates careful interpretation when employing this system in clinical laboratories.

Hong S, et al. J Korean Med Sci. 2026 Jan;41:e35. https://doi.org/10.3346/jkms.2026.41.e35

Given its narrow therapeutic index and risk of nephrotoxicity, vancomycin requires accurate concentration monitoring. While immunoassays such as the Kinetic Interaction of Microparticles in Solution (KIMS) are widely used for their speed and simplicity, they are susceptible to interference by paraproteins such as monoclonal immunoglobulins. Here, we present the first case of falsely elevated vancomycin concentrations measured by KIMS due to monoclonal IgM interference, indicated by a 'kinetic flag' error, and evaluated pre-analytical approaches to mitigate this interference. We applied three pre-analytical techniques to overcome this issue: dithiothreitol (DTT) treatment to reduce disulfide bonds in IgM, ultrafiltration with a 100-kDa cutoff to physically remove IgM molecules, and heterophilic blocking tubes (HBT) to neutralize nonspecific binding by heterophilic antibodies. Vancomycin concentrations were measured using both KIMS (Cobas c702, Roche Diagnostics) and Chemiluminescent Microparticle Immunoassay (CMIA, Architect i2000SR, Abbott Laboratories). In pre-vancomycin-dose samples, both DTT treatment and ultrafiltration resolved the 'kinetic flag' error and corrected vancomycin concentrations to below the lower limit of quantification (LLOQ). In post-vancomycin-dose samples, DTT reduced vancomycin concentration to 16.82 μg/mL (93.8% of the naïve concentration), while ultrafiltration reduced it to 9.22 μg/mL (51.4%). HBT treatment did not resolve the error, and falsely elevated results persisted. This study reports the first case of IgM paraprotein interfering with vancomycin measurement by KIMS, underlining the importance of recognizing monoclonal IgM as a potential source of interference. DTT treatment effectively corrected the interference, while ultrafiltration reduced vancomycin concentration, highlighting the need for careful interpretation.