Background: Copeptin is secreted in equimolar amounts as arginine vasopressin, main hormone regulating body fluid homeostasis. A recent study reported a copeptin-based classification of osmoregulatory defects in syndromes of inappropriate antidiuresis that may aid in prediction of therapeutic success. We investigated usefulness of copeptin for differentiating etiologies of hyponatremia and predicting efficacy and safety of hypertonic saline treatment in hyponatremic patients. Methods: We performed a multicenter, prospective cohort study of 100 inpatients with symptomatic hyponatremia (corrected serum sodium [sNa] ≤ 125 mmol/L) treated with hypertonic saline. Copeptin levels were measured at baseline and 24 hours after treatment initiation, and patients were classified as being below or above median of copeptin at baseline or at 24 hours, respectively. Correlations between target, under correction, and overcorrection rates of sNa within 24 hours/24–48 hours and copeptin levels at baseline/24 hours were analyzed. Results: Mean sNa and median copeptin levels were 117.9 and 16.9 pmol/L, respectively. Ratio of copeptin-to-urine sodium allowed for an improved differentiation among some (insufficient effective circulatory volume), but not all hyponatremia etiologic subgroups. Patients with below-median copeptin levels at baseline achieved a higher target correction rate in 6/24 hours (odds ratio [OR], 2.97; p = 0.02/OR, 6.21; p = 0.006). Patients with below-median copeptin levels 24 hours after treatment showed a higher overcorrection rate in next 24 hours (OR, 18.00, p = 0.02). Conclusion There is a limited diagnostic utility of copeptin for differential diagnosis of hyponatremia. However, copeptin might be useful for predicting responses to hypertonic saline treatment in hyponatremic patients.

Background/Aims: This study aimed to assess the association between local and systemic reactogenicity and humoral immunogenicity after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. Methods: Adverse events were prospectively evaluated using an electronic diary in 135 healthy adults who received a SARS-CoV-2 vaccine (AZD1222, AstraZeneca/Oxford, n = 42; or BNT162b2, Pfizer/BioNTech, n = 93). We semi-quantitatively measured anti-S1 immunoglobulin G (IgG) using an enzyme-linked immunosorbent assay at baseline, 3 weeks after the first dose of AZD1222 or BNT162b2, and 2 weeks after the second dose of BNT162b2. We evaluated the association between the maximum grade of local or systemic adverse events and the anti-S1 IgG optical density using multivariate linear regression with adjustment for age, sex, and use of antipyretics. Results: The median age of the 135 vaccinees was 30 years (36 years in the AZD1222 group and 29 years in the BNT162b2 group) and 25.9% were male (9.5% in the AZD1222 group and 33.3% in the BNT162b2 group). Local and systemic adverse events were generally comparable after the first dose of AZD1222 and the second dose of BNT162b2. The grades of local and systemic adverse events were not significantly associated with anti-S1 IgG levels in the AZD1222 or BNT162b2 group. Conclusions Local and systemic reactogenicity may not be associated with humoral immunogenicity after SARS-CoV-2 vaccination.

Background: s: Recently, alternative surrogate endpoints such as a 30% or 40% decline in estimated glomerular filtration rate (eGFR) or eGFR slope over 2 to 3 years have been proposed for predicting renal outcomes. However, the impact of GFR estimation methods on the accuracy and effectiveness of surrogate markers is unknown. Methods: We retrospectively enrolled participants in health screening programs at three hospitals from 1995 to 2009. We defined two different participant groups as YR1 and YR3, which had available 1-year or 3-year eGFR values along with their baseline eGFR levels. We compared the effectiveness of eGFR percentage change or slope to estimate end-stage renal disease (ESRD) risk according to two estimating equations (modified Modification of Diet in Renal Disease equation [eGFRm] and Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation [eGFRc]) for GFR. Results: In the YR1 and YR3 groups, 9,971 and 10,171 candidates were enrolled and ESRD incidence during follow-up was 0.26% and 0.19%, respectively. The eGFR percentage change was more effective than eGFR slope in estimating ESRD risk, regardless of the method of estimation. A 40% of decline in eGFR was better than 30%, and a 3-year baseline period was better than a 1-year period for prediction accuracy. Although some diagnostic indices from the CKD-EPI equation were better, we found no significant differences in the discriminative ability and hazard ratios for incident ESRD between eGFRc and eGFRm in either eGFR percentage change or eGFR slope. Conclusion There were no significant differences in the prediction accuracy of GFR percentage change or eGFR slope between eGFRc and eGFRm in the general population.

Background: s: Recently, alternative surrogate endpoints such as a 30% or 40% decline in estimated glomerular filtration rate (eGFR) or eGFR slope over 2 to 3 years have been proposed for predicting renal outcomes. However, the impact of GFR estimation methods on the accuracy and effectiveness of surrogate markers is unknown. Methods: We retrospectively enrolled participants in health screening programs at three hospitals from 1995 to 2009. We defined two different participant groups as YR1 and YR3, which had available 1-year or 3-year eGFR values along with their baseline eGFR levels. We compared the effectiveness of eGFR percentage change or slope to estimate end-stage renal disease (ESRD) risk according to two estimating equations (modified Modification of Diet in Renal Disease equation [eGFRm] and Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation [eGFRc]) for GFR. Results: In the YR1 and YR3 groups, 9,971 and 10,171 candidates were enrolled and ESRD incidence during follow-up was 0.26% and 0.19%, respectively. The eGFR percentage change was more effective than eGFR slope in estimating ESRD risk, regardless of the method of estimation. A 40% of decline in eGFR was better than 30%, and a 3-year baseline period was better than a 1-year period for prediction accuracy. Although some diagnostic indices from the CKD-EPI equation were better, we found no significant differences in the discriminative ability and hazard ratios for incident ESRD between eGFRc and eGFRm in either eGFR percentage change or eGFR slope. Conclusion There were no significant differences in the prediction accuracy of GFR percentage change or eGFR slope between eGFRc and eGFRm in the general population.

Background: The significance of ambulatory blood pressure (ABP) in Korean patients with chronic kidney disease (CKD) in relation to renal outcome or death remains unclear. We investigated the role of ABP in predicting end-stage renal disease or death in patients with CKD. Methods: We enrolled 387 patients with hypertension and CKD who underwent ABP monitoring and were followed for 1 year. Data on clinical parameters and outcomes from August 2014 to May 2018 were retrospectively collected. The composite endpoint was end-stage renal disease or death. Patients were grouped according to the mean ABP. Results: There were 66 endpoint events, 52 end-stage renal disease cases, and 15 mortalities. Among all patients, one developed end-stage renal disease and died. Mean ABP in the systolic and diastolic phases were risk factors for the development of composite outcome with hazard ratios of 1.03 (95% confidence interval [CI], 1.01-1.04; P < 0.001) and 1.04 (95% CI, 1.02-1.07; P = 0.001) for every 1 mmHg increase in BP, respectively. Patients with mean ABP between 125/75 and 130/80 mmHg had a 2.56-fold higher risk for the development of composite outcome (95% CI, 0.72-9.12; P = 0.147) as compared to those with mean ABP ≤ 125/75 mmHg. Patients with mean ABP ≥ 130/80 mmHg had a 4.79-fold higher risk (95% CI, 1.68-13.70; P = 0.003) compared to those with mean ABP ≤ 125/75 mmHg. Office blood pressure (OBP) was not a risk factor for the composite outcome when adjusted for covariates. Conclusion In contrast to OBP, ABP was a significant risk factor for end-stage renal disease or death in CKD patients.

Background: Serum uric acid (SUA) is recognized as a risk factor for chronic kidney disease (CKD) and mortality. However, there is controversy as to whether a high or low level of SUA is related to the risk of CKD progression or death, and whether it differs between males and females. Methods: We included 143,762 adults who underwent voluntary health screening between 1995 and 2009 in Korea. For each sex, we divided participants into sex-specific quintiles according to SUA levels and compared end-stage renal disease (ESRD) incidence and mortality between the groups with low and high SUA levels and those with middle SUA levels. Sex-specific Cox proportional hazard analyses were performed for ESRD and all-cause mortality. Results: Among the 143,762 participants, 0.2% (n = 272) developed ESRD. The hazard ratio (HR) of ESRD was higher in the highest (adjusted HR, 2.13; 95% confidence interval [CI], 1.18–3.84) and lowest (adjusted HR, 1.90; 95% CI, 1.02–3.51) SUA quintiles than in the middle SUA quintile in males and the highest SUA quintile in females (adjusted HR, 2.31; 95% CI, 1.10–4.84). Four-point three percent (n = 6,215) of participants died during a mean follow-up period of 157 months. The hazard ratio (HR) of all-cause mortality was higher in the highest SUA quintile than in the middle SUA quintile in males (adjusted HR, 1.15; 95% CI, 1.03–1.28) and females (adjusted HR, 1.17; 95% CI, 1.01–1.35). Conclusion Elevated levels of SUA are associated with increased risk for ESRD and all-cause mortality in both sexes. Low levels of SUA might be related to ESRD and death only in males, showing U-shaped associations. Our findings suggest sex-specific associations between SUA levels and ESRD development and mortality.