Jang HJ, et al. J Korean Med Sci. 2019 Nov;35(1):e5. https://doi.org/10.3346/jkms.2020.35.e5

Even low levels of toxic metal exposure (As, Cd, Hg, and Pb) in infancy might be harmful to children’s development. This study investigated toxic metal exposure on healthy weaning-age infants and its relationship with growth, diet, and iron/anemia status. The weight, height, head circumference, whole blood levels of four toxic metals, hemoglobin, and serum ferritin of healthy infants was measured. Among 210 infants with a median age of 11.4 months (interquartile range: 10.5–12.0), the median levels of As, Cd, Hg, and Pb were 1.2 μg/L, 0.05 μg/L, 0.8 μg/L, and 0.83 μg/dL, respectively. In adjusted linear regression models, post-birth weight gain (Pb) and current head circumference (As, Pb) were negatively associated with toxic metal levels. In multiple linear regression or logistic regression analysis, the duration of breastfeeding (all four metals), perceived adequacy of rice-based food intake (As), regular fish intake (As, Hg), and iron deficiency with/without anemia (Cd, Pb) were associated with increased toxic metal levels. Although levels of toxic metals may not usually be high in this population, individual exposure risk may need to be assessed after considering the type of feeding or intake of complementary foods and the iron/anemia status while evaluating growth status during late infancy.

Background: The SARS-CoV-2 variants of concern exhibit distinct features in terms of transmissibility and virulence. This study compared the clinical characteristics of COVID-19 in children during pre-Delta, Delta and Omicron waves. Methods: Medical records of 1163 children <19 years of age with COVID-19 admitted to a designated hospital in Seoul, South Korea, were analyzed. Clinical and laboratory findings during the pre-Delta (March 1, 2020, to June 30, 2021; 330 children), Delta (July 1, 2021, to December 31, 2021; 527 children) and Omicron (January 1, 2022, to May 10, 2022; 306 children) waves were compared. Results: Children during the Delta wave were older and had a higher proportion of fever ≥5 days and pneumonia than children during the pre-Delta and Omicron waves. The Omicron wave was characterized by younger age and a higher proportion of fever ≥39.0 °C, febrile seizure and croup. More children <2 years of age and adolescents aged 10 to <19 years experienced neutropenia and lymphopenia, respectively, during the Delta wave. Children aged 2 to <10 years had a higher incidence of leukopenia and lymphopenia during the Omicron wave. Conclusions: Distinct features of COVID-19 were observed in children during the Delta and Omicron surges. Continuous scrutiny of the manifestations of variants of concern is needed for appropriate public health response and management.

Kim A, et al. J Korean Med Sci. 2017 Mar;32(3):465-474. https://doi.org/10.3346/jkms.2017.32.3.465

An elevated alanine aminotransferase (ALT) level is a surrogate marker of non-alcoholic fatty liver disease (NAFLD), the most common liver disorder in adolescents. The majority of previous NAFLD studies in adolescents were performed in selected obese populations or had a cross-sectional design without a time-trend analysis. The purpose of this study was to estimate the prevalence and time trends of elevated ALT levels in a general adolescent population and to identify factors associated with ALT elevation. We analysed data of adolescent participants (aged 10–18 years) from the Korean National Health and Nutrition Examination Survey 2001–2014, a representative sample of the general population in South Korea. Suspected NAFLD was defined as ALT elevation (> 30 U/L) without hepatitis B surface antigen. In all statistical analyses, sampling weight- and design-based data were used. ALT was elevated in 5.3% (standard error: 0.3%) of the study population of adolescent participants (N = 8455). No significant trends were found from 2001 to 2014 in the prevalence of elevated ALT among male and female adolescents. In multiple logistic regression analysis, elevated ALT was independently associated with sex (odds ratio [OR] male versus female 4.5; 95% CI, 3.3-6.2), obesity (OR 7.6; 95% CI, 5.3-11.0), and truncal obesity (OR 2.5; 95% CI, 1.8-3.5). Furthermore, male sex, obesity, truncal obesity and high household income level were associated with log-transformed ALT levels in multiple regression analysis. In Korean adolescents of both genders, the prevalence of elevated ALT levels was stable from 2001 to 2014. This study has revealed that sex, obesity, truncal obesity and household income level are associated with ALT elevation in adolescents.

Hong J, et al. J Korean Med Sci. 2023 Aug;38(33):e261. https://doi.org/10.3346/jkms.2023.38.e261