Hyperthyroidism is a clinical condition characterized by excessive production of thyroid hormones, leading to thyrotoxicosis, with Graves’ disease being the most common underlying etiology. The treatment options for hyperthyroidism include antithyroid drug (ATD) therapy, radioactive iodine (RAI) therapy, and thyroidectomy. To establish standardized clinical recommendations specific to RAI therapy focusing on the safety, efficacy, pre- and post-treatment protocols, and follow-up monitoring, the Korean Thyroid Association convened a Task Force dedicated to developing evidence-based guidelines. Six key clinical questions were identified through expert panel discussion. A systematic review of literature published between 2013 and 2022 was conducted using PubMed and Embase with “hyperthyroidism” and “Graves’ disease” as search terms. Additional studies published during manuscript development were also included. The guideline classifies the clinical indications for RAI therapy into three categories: cases in which RAI is strongly recommended, may be considered, or not recommended. A fixed dose of 10–15 mCi is recommended for RAI therapy. While a routine low-iodine diet is not required, patients should avoid iodine-rich foods for at least one week before treatment. ATD should be discontinued 3–7 days prior to RAI and may be resumed afterward in selected cases. Prophylactic glucocorticoids are advised for patients with mild active thyroid eye disease and may be considered in those with additional risk factors. Thyroid function should be monitored at 4–6 weeks post-treatment, then every 2–3 months until stabilization, and subsequently at 6–12 month intervals or as clinically indicated. This guideline reflects recent advances in RAI therapy for hyperthyroidism and emphasizes the importance of individualized treatment decisions based on clinical characteristics, comorbidities, and patient preferences in Korea.

The increasing detection of papillary thyroid microcarcinoma (PTMC) has raised concerns about overtreatment.For low-risk PTMC, either immediate surgery or active surveillance (AS) can be considered. To support AS implementation, the Korean Thyroid Association convened a multidisciplinary panel and developed the first Korean guideline. AS is recommended to adults with pathologically proven Bethesda V-VI PTMC without clinical evidence of lymph node or distant metastasis, gross extrathyroidal extension, tracheal or recurrent laryngeal nerve invasion, or aggressive histology. Baseline assessment requires high‑resolution cervical ultrasound by experienced operators to rule out extrathyroidal extension, tracheal or recurrent laryngeal nerve invasion, and lymph node metastasis;contrast‑enhanced neck computed tomography is optional. Patient characteristics such as age, comorbidities, and capacity for long-term follow-up should be assessed. Shared decision-making should weigh the benefits and risks of surgery and AS, expected oncologic outcomes, complications, quality of life, anxiety, medical cost, and patient preference. Follow-up includes cervical ultrasound and thyroid function test every six months for two years, then annually. Disease progression, defined as significant tumor growth or newly detected nodal or distant metastasis, warrants surgery. Despite remaining uncertainties, this guideline offers a framework to ensure oncologic safety and support patient-centered active surveillance.

Hypertension is a major cardiovascular risk factor in hemodialysis patients. This study identified the optimal blood pressure (BP) target for Korean hemodialysis patients using the Korean Renal Dialysis System (KORDS) dataset from the Korean Society of Nephrology and a pooled analysis for previous studies. Methods: Hemodialysis patients were classified according to their systolic (SBP) and diastolic BP (DBP) at intervals of 20 and 10 mmHg, respectively. As a primary and secondary outcome, all-cause mortality and cardiovascular mortality were evaluated. Subsequently, pooled analysis with previous literatures was performed. Results: Among 70,607 patients, 13,708 (19.4%) died in 2,426 days (interquartile range, 1,256–4,075 days). Mean SBP and DBP were 143.0 ± 19.6 and 78.5 ± 12.0 mmHg. In multivariable Cox regression, the patients with SBP of <120 and ≥180 mmHg showed 1.10- and 1.12-times increased risk of all-cause mortality compared to SBP of 120–140 mmHg. Meanwhile, DBP showed no significant association. In subgroup analysis, patients aged <70 years and without diabetes had a U-shaped SBP-mortality association. Cardiovascular mortality was increased in SBP of ≥160 mmHg compared to 120–140 mmHg, but it was not in <120 mmHg. Pooled analysis with previous studies mostly showed elevated risk in SBP of <120 mmHg, but the risks in 140–160 and 160–180 mmHg were not consistent. Conclusion: Extremely lowering BP (<120 mmHg) or uncontrolled hypertension (≥160 mmHg) should be avoided to optimize survival in Korean hemodialysis patients. Detailed analysis for patients with SBP of 120–160 mmHg should be studied further under uniform BP measurement, along with consideration of risk of intradialytic hypotension. Tailored recommendations regarding patient risk factors also should be considered.

Objectives: We analyzed the correlation between the infectivity and transmissibility of the severe acute respiratory syndrome coronavirus 2 Omicron sublineages BA.1, BA. 2, BA.4, and BA.5. Methods: We assessed viral replication kinetics and infectivity at the cellular level. Nasopharyngeal and oropharyngeal specimens were obtained from patients with coronavirus disease 2019, confirmed using whole-genome sequencing to be caused by the Omicron sublineages BA.1, BA.2, BA.4, or BA.5. These specimens were used to infect Vero E6 cells, derived from monkey kidneys, for the purpose of viral isolation. Viral stocks were then passaged in Vero E6 cells at a multiplicity of infection of 0.01, and culture supernatants were harvested at 12-hour intervals for 72 hours. To evaluate viral replication kinetics, we determined the cycle threshold values of the supernatants using real-time reverse transcription polymerase chain reaction and converted these values to genome copy numbers. Results: The viral load was comparable between BA.2, BA.4, and BA.5, whereas BA.1 exhibited a lower value. The peak infectious load of BA.4 was approximately 3 times lower than that of BA.2 and BA.5, while the peak load of BA.2 and BA.5 was about 7 times higher than that of BA.1. Notably, BA.1 demonstrated the lowest infectivity over the entire study period. Conclusion Our results suggest that the global BA.5 wave may have been amplified by the higher viral replication and infectivity of BA.5 compared to other Omicron sublineages. These analyses could support the rapid assessment of the impact of novel variants on case incidence.

Purpose: Nutritional support for adult critically ill patients is essential due to the high risk of malnutrition, which can lead to severe complications. This paper aims to develop evidence-based guidelines to optimize nutritional support in intensive care units (ICUs). Methods: The Grading Recommendations, Assessment, Development and Evaluation process was used to develop and summarize the evidence on which the recommendations were based. Clinical outcomes were assessed for seven key questions. Results: We recommend the following: (1) initiate enteral nutrition (EN) within 48 hours after treatment as it is associated with improved outcomes, including reduced infection rates and shorter ICU stays; (2) early EN is preferred over early parenteral nutrition due to better clinical outcomes; (3) the use of supplementary parenteral nutrition to meet energy targets during the first week of ICU admission in patients receiving early EN is conditionally recommended based on patient-specific needs; (4) limited caloric support should be supplied to prevent overfeeding and related complications, particularly in the early phase of critical illness; (5) higher protein intake is suggested to improve clinical outcomes, such as muscle preservation and overall recovery; (6) additional enteral or parenteral glutamine is conditionally recommended against due to the lack of significant benefit and potential harm; and (7) fish oil-containing lipid emulsions is conditionally recommended due to their potential to enhance clinical outcomes, including reduced infection rates and shorter ICU stays. Conclusion These evidence-based recommendations can improve clinical outcomes and support healthcare providers in making informed decisions about nutritional interventions in the ICU.

Purpose: Nutritional support for adult critically ill patients is essential due to the high risk of malnutrition, which can lead to severe complications. This paper aims to develop evidence-based guidelines to optimize nutritional support in intensive care units (ICUs). Methods: The Grading Recommendations, Assessment, Development and Evaluation process was used to develop and summarize the evidence on which the recommendations were based. Clinical outcomes were assessed for seven key questions. Results: We recommend the following: (1) initiate enteral nutrition (EN) within 48 hours after treatment as it is associated with improved outcomes, including reduced infection rates and shorter ICU stays; (2) early EN is preferred over early parenteral nutrition due to better clinical outcomes; (3) the use of supplementary parenteral nutrition to meet energy targets during the first week of ICU admission in patients receiving early EN is conditionally recommended based on patient-specific needs; (4) limited caloric support should be supplied to prevent overfeeding and related complications, particularly in the early phase of critical illness; (5) higher protein intake is suggested to improve clinical outcomes, such as muscle preservation and overall recovery; (6) additional enteral or parenteral glutamine is conditionally recommended against due to the lack of significant benefit and potential harm; and (7) fish oil-containing lipid emulsions is conditionally recommended due to their potential to enhance clinical outcomes, including reduced infection rates and shorter ICU stays. Conclusion These evidence-based recommendations can improve clinical outcomes and support healthcare providers in making informed decisions about nutritional interventions in the ICU.

Purpose: Nutritional support for adult critically ill patients is essential due to the high risk of malnutrition, which can lead to severe complications. This paper aims to develop evidence-based guidelines to optimize nutritional support in intensive care units (ICUs). Methods: The Grading Recommendations, Assessment, Development and Evaluation process was used to develop and summarize the evidence on which the recommendations were based. Clinical outcomes were assessed for seven key questions. Results: We recommend the following: (1) initiate enteral nutrition (EN) within 48 hours after treatment as it is associated with improved outcomes, including reduced infection rates and shorter ICU stays; (2) early EN is preferred over early parenteral nutrition due to better clinical outcomes; (3) the use of supplementary parenteral nutrition to meet energy targets during the first week of ICU admission in patients receiving early EN is conditionally recommended based on patient-specific needs; (4) limited caloric support should be supplied to prevent overfeeding and related complications, particularly in the early phase of critical illness; (5) higher protein intake is suggested to improve clinical outcomes, such as muscle preservation and overall recovery; (6) additional enteral or parenteral glutamine is conditionally recommended against due to the lack of significant benefit and potential harm; and (7) fish oil-containing lipid emulsions is conditionally recommended due to their potential to enhance clinical outcomes, including reduced infection rates and shorter ICU stays. Conclusion These evidence-based recommendations can improve clinical outcomes and support healthcare providers in making informed decisions about nutritional interventions in the ICU.

Purpose: This study aimed to compare tumor tissue DNA (ttDNA) and circulating tumor DNA (ctDNA) to explore the clinical applicability of ctDNA and to better understand clonal evolution in patients with metastatic colorectal cancer undergoing palliative first-line systemic therapy. Materials and Methods: We performed targeted sequencing analysis of 88 cancer-associated genes using germline DNA, ctDNA at baseline (baseline-ctDNA), and ctDNA at progressive disease (PD-ctDNA). The results were compared with ttDNA data. Results: Among 208 consecutively enrolled patients, we selected 84 (41 males; median age, 59 years; range, 35 to 90 years) with all four sample types available. A total of 202 driver mutations were found in 34 genes. ttDNA exhibited the highest mutation frequency (n=232), followed by baseline-ctDNA (n=155) and PD-ctDNA (n=117). Sequencing ctDNA alongside ttDNA revealed additional mutations in 40 patients (47.6%). PD-ctDNA detected 13 novel mutations in 10 patients (11.9%) compared to ttDNA and baseline-ctDNA. Notably, seven mutations in five patients (6.0%) were missense or nonsense mutations in APC, TP53, SMAD4, and CDH1 genes. In baseline-ctDNA, higher maximal variant allele frequency (VAF) values (p=0.010) and higher VAF values of APC (p=0.012), TP53 (p=0.012), and KRAS (p=0.005) mutations were significantly associated with worse overall survival. Conclusion While ttDNA remains more sensitive than ctDNA, our ctDNA platform demonstrated validity and potential value when ttDNA was unavailable. Post-treatment analysis of PD-ctDNA unveiled new pathogenic mutations, signifying cancer’s clonal evolution. Additionally, baseline-ctDNA’s VAF values were prognostic after treatment.

Purpose: Notable effectiveness of trastuzumab deruxtecan in patients with human epidermal growth factor receptor 2 (HER2)–low advanced breast cancer (BC) has focused pathologists’ attention. We studied the incidence and clinicopathologic characteristics of HER2-low BC, and the effects of immunohistochemistry (IHC) associated factors on HER2 IHC results. Materials and Methods: The Breast Pathology Study Group of the Korean Society of Pathologists conducted a nationwide study using real-world data on HER2 status generated between January 2022 and December 2022. Information on HER2 IHC protocols at each participating institution was also collected. Results: Total 11,416 patients from 25 institutions included in this study. Of these patients, 40.7% (range, 6.0% to 76.3%) were classified as HER2-zero, 41.7% (range, 10.5% to 69.1%) as HER2-low, and 17.5% (range, 6.7% to 34.0%) as HER2-positive. HER2-low tumors were associated with positive estrogen receptor and progesterone receptor statuses (p < 0.001 and p < 0.001, respectively). Antigen retrieval times (≥ 36 minutes vs. < 36 minutes) and antibody incubation times (≥ 12 minutes vs. < 12 minutes) affected on the frequency of HER2 IHC 1+ BC at institutions using the PATHWAY HER2 (4B5) IHC assay and BenchMark XT or Ultra staining instruments. Furthermore, discordant results between core needle biopsy and subsequent resection specimen HER2 statuses were observed in 24.1% (787/3,259) of the patients. Conclusion The overall incidence of HER2-low BC in South Korea concurs with those reported in previously published studies. Significant inter-institutional differences in HER2 IHC protocols were observed, and it may have impact on HER2-low status. Thus, we recommend standardizing HER2 IHC conditions to ensure precise patient selection for targeted therapy.

Differentiated thyroid cancer demonstrates a wide range of clinical presentations, from very indolent cases to those with an aggressive prognosis. Therefore, diagnosing and treating each cancer appropriately based on its risk status is important. The Korean Thyroid Association (KTA) has provided and amended the clinical guidelines for thyroid cancer management since 2007. The main changes in this revised 2024 guideline include 1) individualization of surgical extent according to pathological tests and clinical findings, 2) application of active surveillance in low-risk papillary thyroid microcarcinoma, 3) indications for minimally invasive surgery, 4) adoption of World Health Organization pathological diagnostic criteria and definition of terminology in Korean, 5) update on literature evidence of recurrence risk for initial risk stratification, 6) addition of the role of molecular testing, 7) addition of definition of initial risk stratification and targeting thyroid stimulating hormone (TSH) concentrations according to ongoing risk stratification (ORS), 8) addition of treatment of perioperative hypoparathyroidism, 9) update on systemic chemotherapy, and 10) addition of treatment for pediatric patients with thyroid cancer.