Pediatric nephrotic syndrome is a clinical condition characterized by severe proteinuria, hypoalbuminemia, hyperlipidemia, and generalized edema, most commonly affecting children aged 2 and 6 years. Although standard oral steroid therapy is effective in managing most cases, relapses are common during childhood. Nephrotic syndrome presents significant challenges due to frequent relapses and the potential side effects of long-term drug therapy. In Korea, the absence of a unified national clinical guideline has led physicians to manage pediatric nephrotic syndrome based on diverse clinical guidelines and individual clinical judgment. To address this, the Korean Society of Pediatric Nephrology has developed an evidence-based guideline specifically tailored to the Korean healthcare system. This guideline provides recommendations for the diagnosis and management of steroid-sensitive nephrotic syndrome in children under the age of 18 years.

The natural course of chronic kidney disease (CKD) progression in children varies according to their underlying conditions. This study aims to identify different patterns of subsequent decline in kidney function and investigate factors associated with different patterns of estimated glomerular filtration rate (eGFR) trajectories. Methods: We analyzed data from the KNOW-Ped CKD (KoreaN cohort study for Outcomes in patients With Pediatric Chronic Kidney Disease), which is a longitudinal, prospective cohort study. A latent class linear mixed model was applied to identify the trajectory groups. Results: In a total of 287 patients, the median baseline eGFR (mL/min/1.73 m2) was 63.3, and the median age was 11.5 years. The eGFR decline rate was –1.54 during a 6.0-year follow-up. The eGFR trajectory over time was classified into four groups. Classes 1 (n = 103) and 2 (n = 11) had a slightly reduced eGFR at enrollment with a stable trend (ΔeGFR, –0.2/year) and a rapid decline eGFR over time (ΔeGFR, –10.5/year), respectively. Class 3 had a normal eGFR (n = 16), and class 4 had a moderately reduced eGFR (n = 157); both these chasses showed a linear decline in eGFR over time (ΔeGFR, –4.1 and –2.4/year). In comparison with classes 1 and 2, after adjusting for age, causes of primary renal disease, and baseline eGFR, nephrotic-range proteinuria was associated with a rapid decline in eGFR (odds ratio, 8.13). Conclusion: We identified four clinically relevant subgroups of kidney function trajectories in children with CKD. Most children showed a linear decline in eGFR; however, there are different patterns of eGFR trajectories.

Background: The need for an objective method for measuring skin hydration levels is becoming increasingly important. Various devices with different measuring principles for assessing skin hydration have been developed and are widely used. Objective: This study aimed to investigate the reproducibility and correlation between clinical evaluation and skin hydration measurement devices that are the most widely used in the field. Methods: A prospective comparative clinical trial was conducted on 184 healthy volunteers. Skin hydration levels were measured using the Corneometer (CM820) and hydration probe (HP: DermaLab Combo) at 3 points: the ventral forearm, the dorsal forearm, and the shin. We used the intraclass correlation coefficient (ICC) to evaluate the reproducibility and Pearson’s correlation coefficient (PCC) to evaluate the correlation of each measurement. Simple linear regression was used to analyze the Corneometer and HP skin hydration value changes according to changes in xerosis severity scale (XSS) values, which were evaluated by clinicians. Results: Both the Corneometer and HP showed significant, excellent reproducibility (ICC for Corneometer: 0.954–0.971, ICC for HP: 0.980–0.986) and significant high positive correlations (PCC: 0.708–0.737) regardless of the measurement site. Both devices showed negative regression coefficients in all measurement sites in XSS analysis, but this was not statistically significant. Conclusion The Corneometer and HP were both accurate and objective skin hydration measuring devices, regardless of the measurement site. Using reliable and objective devices such as the Corneometer or HP can aid in understanding an individual’s skin condition and making more informed decisions for skin care.

Remarkable advances in genetic diagnosis expanded our knowledge about inherited tubulopathies and other genetic kidney diseases. This review suggests a simple categorization of inherited tubular disease, clarifies the concept of autosomal dominant tubulointerstitial kidney disease (ADTKD), and introduces novel therapies developed for tubulopathies. Facing patients with suspicious tubular disorders, clinicians should first evaluate the status of volume and acid-base. This step helps the clinicians to localize the affected segment and to confirm genetic diagnosis. ADTKD is a recently characterized disease entity involving tubules. The known causative genes are UMOD, MUC1, REN, and HNF1β. Still, only half of ADTKD patients show mutations for these four identified genes. Whole exome sequencing is a suitable diagnostic tool for tubulopathies, especially for ADTKD. Genetic approaches to treat tubulopathies have progressed recently. Despite the practical obstacles, novel therapies targeting inherited tubulopathies are currently in development.

The administration of angiotensin type 2 receptor blockers (ARBs) during pregnancy is known to cause ARB fetopathy, including renal insufficiency. We aimed to analyze the outcomes of two patients who survived ARB fetopathy and perform an accompanying literature review. Case 1 was exposed antenatally from a gestational age of 30 weeks to valsartan because of maternal pregnancy-induced hypertension. The patient presented with oliguria immediately after birth, and renal replacement therapy was administered for 24 days. Seven years after birth, renal function was indicative of stage 2 chronic kidney disease (CKD) with impaired urinary concentration. Case 2 had a maternal history of hypertension and transient ischemic attack and was treated with olmesartan until 30 weeks of pregnancy. Renal replacement therapy was performed for 4 days since birth. After 8 years, the patient is with CKD stage 2, with intact tubular function. Recent reports suggest that ARB fetopathy might manifest as renal tubular dysgenesis and nephrogenic diabetes insipidus, in contrast to mild alterations of glomerular filtration. Tubular dysfunction may induce CKD progression and growth retardation. Patients with ARB fetopathy should be monitored until adulthood. The ARB exposure period might be a critical factor in determining the severity and manifestations of fetopathy.

Background: Pediatric urinary tract infection (UTI) caused by extended-spectrum β-lactamase (ESBL)-positive gram-negative bacilli (GNB) has limited options for oral antibiotic treatment. The purpose of this study was to investigate the susceptibility of ESBLpositive Escherichia coli and Klebsiella pneumoniae isolates from pediatric urine samples to two oral antibiotics (fosfomycin and nitrofurantoin). Methods: From November 2020 to April 2022, ESBL-positive E. coli and K. pneumoniae isolates from urine samples were collected at Samsung Medical Center, Seoul, Korea. Patients over 18 years of age or with malignancy were excluded. For repeated isolates from the same patient, only the first isolate was tested. Minimum inhibitory concentrations (MICs) were measured using agar (fosfomycin) or broth (nitrofurantoin) dilution methods. MIC 50 and MIC 90 were measured for fosfomycin and nitrofurantoin in both E. coli and K. pneumoniae. Results: There were 117 isolates from 117 patients, with a median age of 7 months (range, 0.0–18.5 years). Among 117 isolates, 92.3% (108/117) were E. coli and 7.7% (9/117) were K. pneumoniae. Isolates from the pediatric intensive care unit (PICU) and general ward (GW) was 11.1% (13/117) and 88.9% (104/117), respectively. Among 108 E. coli isolates, MIC 50 and MIC 90 for fosfomycin were 0.5 μg/mL and 2 μg/mL, respectively. Fosfomycin susceptibility rate was 97.2% (105/108) with a breakpoint of 128 μg/mL. Fosfomycin susceptibility rate was significantly lower in PICU isolates than in GW isolates (81.8% vs. 99.0%, P = 0.027).For nitrofurantoin, both the MIC 50 and MIC 90 were 16 μg/mL. Nitrofurantoin susceptibility rate was 96.3% (104/108) with a breakpoint of 64 μg/mL based on Clinical and Laboratory Standards Institute guidelines. Among the nine K. pneumoniae isolates, the MIC 50 and MIC 90 for fosfomycin was 2 μg/mL and 32 μg/mL, respectively. MIC 50 and MIC 90 for nitrofurantoin were 64 μg/mL and 128 μg/mL, respectively. Conclusion For uncomplicated UTI caused by ESBL-positive GNB in Korean children, treatment with fosfomycin and nitrofurantoin for E. coli infections can be considered as an effective oral therapy option.

Purpose: To determine the prevalence, clinical manifestations, and outcomes of renal involvements in pediatric Alagille syndrome (ALGS). Methods: A total of 21 patients diagnosed with ALGS at age under 18 years who visited Samsung Medical Center from March 1999 to March 2022 were enrolled. ALGS was diagnosed either by clinical manifestations, targeted JAG1 sequencing, and/or liver biopsy. Medical records including sex, age, renal manifestations, urinalysis, serum creatinine, JAG1 sequencing, and ultrasonography were retrospectively reviewed. Results: The male to female ratio was 9:12. The mean age of patients at confirmative diagnosis of ALGS was 18.4 months. Sanger sequencing was performed for 17 patients. Sixteen of 21 patients (76.1%) showed JAG1 mutations. Renal involvement was found in 10 patients (47.6%). The most common type of anomaly was renal dysplasia (40%). One patient having renal dysplasia was pathologically confirmed with glomerular lipid deposition. Two patients (20%) manifested nephrocalcinosisephrolithiasis. Among eight renal-involved patients who survived, four (50%) progressed to chronic kidney disease stage 3. Two of these chronic kidney disease patients were diagnosed with hepatorenal syndrome. The other four patients had renal functions preserved, including two without any interventions and two who underwent urological interventions. Conclusions The current study revealed a high prevalence of renal involvement in Korean pediatric ALGS with diverse phenotypes.

Background: The clinical features of pediatric rhabdomyolysis differ from those of the adults with rhabdomyolysis; however, multicenter studies are lacking. This study aimed to investigate the characteristics of pediatric rhabdomyolysis and reveal the risk factors for acute kidney injury (AKI) in such cases. Methods: This retrospective study analyzed the medical records of children and adolescents diagnosed with rhabdomyolysis at 23 hospitals in South Korea between January 2007 and December 2016. Results: Among 880 patients, those aged 3 to 5 years old composed the largest subgroup (19.4%), and all age subgroups were predominantly male. The incidence of AKI was 11.3%. Neurological disorders (53%) and infection (44%) were the most common underlying disorder and cause of rhabdomyolysis, respectively. The median age at diagnosis in the AKI subgroup was older than that in the non-AKI subgroup (12.2 years vs. 8.0 years). There were no significant differences in body mass index, myalgia, dark-colored urine, or the number of causal factors between the two AKI-status subgroups. The multivariate logistic regression model indicated that the following factors were independently associated with AKI: multiorgan failure, presence of an underlying disorder, strong positive urine occult blood, increased aspartate aminotransferase and uric acid levels, and reduced calcium levels. Conclusions Our study revealed characteristic clinical and laboratory features of rhabdomyolysis in a Korean pediatric population and highlighted the risk factors for AKI in these cases. Our findings will contribute to a greater understanding of pediatric rhabdomyolysis and may enable early intervention against rhabdomyolysis-induced AKI.