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Purpose Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers (ARBs) are frequently employed to counteract the detrimental effects of proteinuria on glomerular diseases. However, the effects of ARBs remain poorly examined in pediatric patients with immunoglobulin A (IgA) nephropathy. Herein, we evaluated the efficacy and safety of losartan, an ARB, in pediatric IgA nephropathy with proteinuria. Methods This prospective, single-arm, multicenter study included children with IgA nephropathy exhibiting proteinuria. Changes in proteinuria, blood pressure, and kidney function were prospectively evaluated before and 4 and 24 weeks after losartan administration. The primary endpoint was the difference in proteinuria between baseline and 24 weeks. Results In total, 29 patients were enrolled and received losartan treatment. The full analysis set included 28 patients who received losartan at least once and had pre- and post-urinary protein to creatinine ratio measurements (n=28). The per-protocol analysis group included 22 patients who completed all scheduled visits without any serious violations during the study period. In both groups, the mean log (urine protein to creatinine ratio) value decreased significantly at 6 months. After 24 weeks, the urinary protein to creatinine ratio decreased by more than 50% in approximately 40% of the patients. The glomerular filtration rate was not significantly altered during the observation period. Conclusions Losartan decreased proteinuria without decreasing kidney function in patients with IgA nephropathy over 24 weeks. Losartan could be safely employed to reduce proteinuria in this patient population. ClinicalTrials.gov trial registration (NCT0223277)

Tolvaptan is a highly selective vasopressin receptor 2 antagonist that regulates cyclic adenosine monophosphate levels to inhibit both epithelial cell proliferation and chloride ion excretion, two mechanisms known to induce cyst expansion in autosomal dominant polycystic kidney disease (ADPKD). Tolvaptan is currently the preferred treatment of rapidly progressive disease ADPKD in adult patients; however, since cyst formation in ADPKD begins early in life, (frequently in utero), and significant disease progression with cyst expansion occurs in the first decade, tolvaptan may be advantageous as a preemptive treatment in children with ADPKD. Tolvaptan has already been used to successfully treat refractory edema or hyponatremia in children; this literature review provides insight into the biochemical basis of its action to contextualize its use in the pediatric population.

Chronic kidney disease (CKD) causes numerous changes that destabilize homeostasis, of which anemia is one of its important complications. Anemia significantly reduces the quality of life in children with CKD and plays a crucial role in the progression of cardiovascular disease such as left ventricular hypertrophy, a major cause of mortality in those with advanced CKD. The treatment of anemia is a pivotal factor in reducing morbidity and mortality rates in children with CKD, representing one of the methods for enhancing patients’ quality of life.

Background Donor–recipient size mismatching is commonly occurs in pediatric kidney transplantation (KT). However, its effect on graft survival remains unknown. This study aimed to determine the effect of donor–recipient size mismatch on the long-term survival rate of transplant kidneys in pediatric KT. Methods A total of 241 pediatric patients who received KT were enrolled. The medical records of all patients were retrospectively reviewed, and the correlation between donor–recipient size mismatch and graft function and long-term graft outcome was analyzed according to donor–recipient size mismatch. Results Recipients and donors’ mean body weight at the time of KT were 34.31 ± 16.85 and 56.53 ± 16.73 kg, respectively. The mean follow-up duration was 96.49 ± 52.98 months. A significant positive correlation was observed between donor–recipient body weight ratio (DRBWR) or donor–recipient body surface area ratio (DRBSR) and graft function until 1 year after KT. However, this correlation could not be confirmed at the last follow-up. The results of long-term survival analysis using Fine and Gray’s subdistribution hazard model showed no significant difference of the survival rate of the transplant kidney according to DRBWR or DRBSR. Conclusion Donor–recipient size mismatch in pediatric KT is not an important factor in determining the long-term prognosis of transplant kidneys.

Coronavirus disease 2019 (COVID-19) has spread considerably across the globe, affecting numerous children and adolescents besides adults. Despite its relatively lower incidence rates in children and adolescents than in adults, some infected children and adolescents exhibit a severe postinflammatory response known as multisystem inflammatory syndrome in children, followed by acute kidney injury, a common complication. Meanwhile, few reports have been available regarding kidney complications such as idiopathic nephrotic syndrome and other glomerulopathies associated with COVID-19 infection and vaccination in children and adolescents. However, the morbidity and mortality of these complications are not exceptionally high; more importantly, causality has yet to be clearly established. Finally, vaccine hesitancy in these age groups should be addressed, considering the strong evidence of COVID-19 vaccine safety and efficacy.

Abstract The genotype–phenotype correlation of the X-linked Alport syndrome (XLAS) has been well elucidated in males, whereas it remains unclear in females. In this multicenter retrospective study, we analyzed the genotype–phenotype correlation in 216 Korean patients (male:female = 130:86) with XLAS between 2000 and 2021. The patients were divided into three groups according to their genotypes: the non-truncating group, the abnormal splicing group, and the truncating group. In male patients, approximately 60% developed kidney failure at the median age of 25.0 years, and kidney survival showed significant differences between the non-truncating and truncating groups (P

Kleefstra syndrome is a rare genetic disease characterized by mental retardation, hypotonia, and a characteristic facial appearance. Furthermore, in some cases, Kleefstra syndrome is associated with various anorectal and genitourinary complications, including imperforated anus, vesicoureteral reflux, hydronephrosis, and chronic kidney disease. Herein, we present a case of Kleefstra syndrome with recurrent urinary tract infections associated with vesicoureteral reflux and rectourethral fistula, which was treated by a multidisciplinary approach.

Purpose Children with nephrotic syndrome may experience disease relapse or aggravation triggered by various viral infections. Limited studies on the clinical implications of the coronavirus disease 2019 (COVID-19) pandemic in children with nephrotic syndrome have been published worldwide. Therefore, this study aimed to investigate the effects of COVID-19 on the clinical course of nephrotic syndrome in children. Methods The medical records of 59 patients with idiopathic nephrotic syndrome who visited our hospital between February and June 2022 were retrospectively analyzed. Results Twenty of the total 59 patients with nephrotic syndrome were diagnosed with COVID-19 during the study period. The mean age at the time of the diagnosis of nephrotic syndrome and COVID-19 in all 20 patients was 4.6±3.5 and 8.9±3.9 years, respectively. Three patients (15%) were diagnosed with nephrotic syndrome relapse during COVID-19 and the relapse rate was similar to them without COVID-19 (20.5%, 8/39 patients). At the time of the COVID-19 diagnosis, fever (85%) and cough (40%) were the most common symptoms. After the diagnosis of COVID-19, all patients showed improvement with symptomatic treatment, including antipyretic analgesics and cold medicine. None of the critical patients required hospitalization or oral antiviral medications. Conclusions Despite the use of immunosuppressants, the clinical manifestations of COVID-19 in children with nephrotic syndrome were not severe and are expected to be similar to that in the general population. The relapse rate of nephrotic syndrome in children with COVID-19 was also not different from them without COVID-19.

Background There have been some cases where abnormal histopathologic findings could not be found in the kidney could even with proper specimen collection through percutaneous renal biopsy (PRB) in accordance with its indication. We analyzed the incidence and clinical outcomes of children who showed normal histopathological findings in their PRBs. Methods The medical records of 552 pediatric subjects who underwent PRB between 2005 and 2016 were reviewed. Twenty-six subjects were excluded because allograft biopsy was performed in nine subjects, and the age at biopsy was greater than 18 years in 17 subjects. Finally, 526 subjects were enrolled in this study. Results Of the 526 pediatric patients, 32 (6.1%) showed no histopathological abnormalities in their PRBs. The male-to-female ratio of the patients was 1.9:1, and the mean ages at the first visit and at biopsy were 10.6 ± 4.1 and 11.4 ± 3.8 years, respectively. In accordance with the biopsy indications, recurrent gross hematuria showed the highest incidence rate, but combined hematuria and proteinuria had the lowest incidence rate regarding normal renal histopathology among all the subjects. At a mean follow-up of 35.5 ± 23.6 months, urinary abnormalities had improved in more than 50% of the subjects with normal renal histopathology, and none of the patients showed progression to end-stage renal disease or required rebiopsy due to symptom worsening during the follow-up period. Conclusion The clinical outcomes of children with normal PRB histopathologic findings are generally good. Further studies to evaluate their long-term outcomes are needed.

BackgroundChildren with chronic kidney disease (CKD) are at high risk of mineral bone disorder (MBD), which leads to fractures, growth retardation, and cardiovascular disease. We aimed to comprehensively understand the relationship between renal function and factors related to MBD and evaluate the prevalence and distribution characteristics of MBD, specifically among Korean patients from the KNOW-PedCKD cohort.MethodsFrom the baseline data of the KNOW-PedCKD cohort, we examined the prevalence and distribution of MBD in 431 Korean pediatric CKD patients, including the level of corrected total calcium, serum phosphate, serum alkaline phosphatase, serum intact parathyroid hormone (iPTH), fibroblast growth factor 23 (FGF-23), serum vitamin D, fractional excretion of phosphate (FEP), and bone densitometry Z-scores.ResultsThe median serum calcium level remained relatively normal regardless of the CKD stage. The levels of 1,25-dihydroxy vitamin D, urine calcium-to-creatinine ratio, and bone densitometry Z-score significantly decreased with advancing CKD stage, while those of serum phosphate, FGF-23, and FEP significantly increased with CKD stage. The prevalence of hyperphosphatemia (17.4%, 23.7%, and 41.2% from CKD stages 3b, 4, and 5, respectively) and hyperparathyroidism (37.3%, 57.4%, 55.3%, and 52.9% from CKD stages 3a, 3b, 4, and 5, respectively) significantly increased with the CKD stage. Prescriptions of medications, such as calcium supplements (39.1%, 42.1%, 82.4%), phosphate binders (39.1%, 43.4%, 82.4%), and active vitamin D (21.7%, 44.7%, and 64.7%) significantly increased with CKD stage 3b, 4, and 5, respectively.ConclusionsThe results demonstrated the prevalence and relationship of abnormal mineral metabolism and bone growth according to CKD stage in Korean pediatric CKD patients for the first time.

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 (53.6%) and infection (39.0%) 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.

Abstract Background Cardiovascular disease (CVD) is the most common cause of mortality in pediatric chronic kidney disease (CKD) patients. Left ventricular (LV) hypertrophy (LVH) is associated with LV diastolic dysfunction (LVDD) development and is used as an early marker of CVD in pediatric CKD. This study aimed to assess the prevalence and risk factors of LVDD and the association between LVH and LVDD in Korean pediatric CKD patients. Methods Data were collected using the baseline data of the Korean cohort study for outcome in patients with pediatric chronic kidney disease, a nationwide, 10-year, prospective, observational cohort study of pediatric CKD. A total of 244 patients were included in the final analysis. Two-dimensional echocardiography and tissue Doppler images were used to evaluate LVH and LVDD. LVH was defined as an LV mass index (LVMI) ≥38 g/m2.7 and LV-wall thickness z-score > 1.64. LVDD was defined as a mitral peak velocity of early filling to early diastolic mitral annular velocity (E/E’) > 14. Univariate and multivariate logistic regression analyses were performed to evaluate risk factors of LVDD. Results In this study, the male-to-female ratio was 2.2 (168:76) and median age was 11.2 years. The average estimated glomerular filtration rate was 57.4 ml/min/1.73 m2, and no patients received renal replacement therapy. The mean value of LVMI and E/E’ was 37.0 g/m2.7 and 7.4, respectively. The prevalence of LVH was 40.1 and 17.4% by LVMI ≥38 g/m2.7 and LV-wall thickness z-score, respectively. The prevalence of LVDD was 4.5%, and patients with LVH showed greater risk of LVDD (odds ratio 7.3, p = 0.012). In the univariate analysis, young age, low hemoglobin level, higher LVMI, and higher LV-wall thickness z-score were associated with LVDD. In the multivariate analysis, young age, low hemoglobin level, and higher LV-wall thickness z-score were independently associated with LVDD. Conclusion This study shows that LVH patients have a greater risk of LVDD and that anemia is the only modifiable risk factor for LVDD in Korean pediatric CKD patients.

Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a rare X-linked genetic condition caused by a gain-of-function mutation of arginine vasopressin receptor 2 gene, AVPR2. We report the case of a male neonate diagnosed with NSIAD based on his DNA sequence of the AVPR2 gene and the clinical course. He demonstrated a complete correction of hyponatremia using oral urea. We suggest that (1) sequencing analysis of the AVPR2 gene ought to be done in newborns with prolonged euvolemic hyponatremia, hypo-osmolality, high urinary sodium and normal/low or undetectable AVP levels, and that (2) oral urea is a safe and effective treatment option in infants diagnosed with NSIAD until the patients are grown-up.

Purpose Alport syndrome (AS) is one of the most common inherited renal diseases caused due to mutations of genes encoding specific proteins of the type IV collagen family, and its major clinical manifestations include progressive renal failure, sensorineural deafness, and ocular abnormalities. We investigated the clinical characteristics and long-term prognosis of AS in Korean pediatric and adult populations. Methods We conducted a retrospective review of medical records of 33 children and adults who had been diagnosed or treated with AS from 1985 to 2019. Results The mean age of the 33 patients diagnosed with AS was 16.2±13.6 years, and the male-to-female ratio was 2:1. At the first visit, recurrent gross hematuria was the most common initial symptom. In 10 of 33 patients (30.3%), sensorineural hearing loss (SNHL) was diagnosed, but none had ophthalmic problems. Moreover, 11 of 33 patients (33.3%) had advanced to end-stage renal disease (ESRD), and a significant difference was observed in the age of the patients who progressed to ESRD based on the presence or absence of SNHL (P=0.035). Conclusion SNHL in AS can be an important prognostic factor for long-term deterioration of renal function. Further investigation is required to confirm the clinical course and the genetic characteristics of AS in Korea through prospective national cohort studies.

Despite the many advantages of peritoneal dialysis (PD) in children with endstage renal disease, there exist redoubtable complications of PD that should be overcome. To prevent and manage these complications, a multidisciplinary team should provide support highly tailored for each child and family, based on the standardized practice guidelines for the management of pediatric PD. In this review, we summarize the clinical manifestations and management of several complications of PD.

Background Acute kidney injury (AKI) is one of the most significant postoperative complications of pediatric cardiac surgery. Because serum creatinine has limitations as a diagnostic marker of AKI, new biomarkers including neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and interleukin-18 (IL-18) are being evaluated to overcome these limitations and detect AKI at an early stage after cardiac surgery. Purpose This study aimed to investigate the clinical usefulness of these biomarkers in young children. Methods Thirty patients with congenital heart diseases who underwent cardiac surgery using cardiopulmonary bypass (CPB) were selected, and their urine and blood samples were collected at baseline and 6, 24, and 48 hours after surgery. Serum creatinine and blood urea nitrogen levels as well as NGAL, KIM-1, and IL-18 levels in urine samples were measured, and clinical parameters were evaluated. Results Of the 30 patients, 12 developed AKI within 48 hours after cardiac surgery. In the AKI group, 8 of 12 (66.6%) met AKI criteria after 24 hours, and urine KIM-1/creatinine (Cr) level (with adjustment of urine creatinine) peaked at 24 hours with significant difference from baseline level. Additionally, urine KIM-1/Cr level in the AKI group was significantly higher than in the non-AKI group at 6 hours. However, urine NGAL/Cr and IL-18/Cr levels showed no specific trend with time for 48 hours after cardiac surgery. Conclusion It is suggested that urine KIM-1/Cr concentration could be considered a good biomarker for early AKI prediction after open cardiac surgery using CPB in young children with congenital heart diseases.

Purpose Ureteral duplication is a relatively common congenital urinary tract abnormality that can be associated with various clinical problems such as vesicoureteral reflux (VUR), hydronephrosis, and ectopic ureters. The purpose of this study was to analyze the clinical characteristics of pediatric patients with recently diagnosed ureteral duplication and to identify any differences from those described in previous reports. Methods We retrospectively reviewed the clinical characteristics and course of pediatric patients who were diagnosed with ureteral duplication between January 2008 and June 2017. Results A total of 32 pediatric patients were diagnosed with ureteral duplication during the study period. The male to female ratio was 1:2.2. Twenty-seven patients (84.4%) were first diagnosed with ureteral duplication at less than 3 months of age, and 26 (81.3%) were first diagnosed by prenatal ultrasonography. Four of the 32 patients were diagnosed with bilateral ureteral duplication, for a total of 36 occurrences of ureteral duplication. In 17 occurrences of complete ureteral duplication (47.2%), other urinary tract anomalies were also found; namely, ureterocele (7), VUR (11), and ectopic ureter (5). However, none of the patients with incomplete ureteral duplication had ureterocele or VUR. Conclusions With the advent of routine prenatal ultrasound, ureteral duplication is being diagnosed earlier than was previously possible, enabling timely treatment of the various accompanying urinary tract anomalies. Multicenter studies are needed to establish guidelines for standardized evaluation and treatment of ureteral duplication.

Purpose The incidence of inflammatory bowel disease (IBD) is rapidly increasing, and several reports have described the renal complications of IBD. We sought to evaluate the clinical manifestations of renal complications in children with IBD in order to enable early detection and prompt treatment of the complications. Methods We retrospectively reviewed the medical records of 456 children and adolescents aged

Kidney transplantation (KT) is the gold standard for renal replacement therapy in pediatric patients with end-stage renal disease. Recently, it has been observed that the outcome of pediatric KT is nearly identical to that in adults owing to the development and application of a variety of immunosuppressants and newer surgical techniques. However, owing to several differences in characteristics between children and adults, pediatric KT requires that additional information be learned and is associated with added concerns. These differences include post-KT complications, donor-recipient size mismatch, problems related to growth, and nonadherence to therapy, among others. This review was aimed at elucidating the clinical characteristics of pediatric KT that differ from those observed in adults.

Proteinuria is common in pediatric and adolescent patients. Proteinuria is defined as urinary protein excretion at levels higher than 100-150 mg/m2/day in children. It can be indicative of normal or benign conditions as well as numerous types of severe underlying renal or systemic disease. The school urine screening program has been conducted in Korea since 1998. Since then, numerous patients with normal or benign proteinuria as well as early stage renal diseases have been referred to the hospital. Benign proteinuria includes orthostatic proteinuria and transient proteinuria. Most causes of proteinuria can be categorized into 3 types: 1) overflow, 2) tubular, and 3) glomerular. Although treatment should be directed at the underlying cause of the proteinuria, prompt evaluation, diagnosis, and long-term monitoring of these pediatric patients can prevent potential progression of the underlying disease process. This article provides an overview of proteinuria: its causes, methods of assessment, and algorithmic suggestions to differentiate benign from pathologic renal disease.

Purpose Kidney transplantation (KT) is an ideal treatment for pediatric patients with end-stage renal disease (ESRD). We report the clinical outcomes of pediatric ESRD patients who underwent KT in a single regional center. Methods We retrospectively investigated the medical records of 60 pediatric patients who were diagnosed with ESRD and underwent KT in our hospital between January 1985 and June 2016. Results A total of 60 children and adolescents (40 male, 20 female; mean age, 13.86±4.26 years) were included in this study. Six patients (10.0%) underwent KT immediately after receiving the diagnosis of ESRD, while the others underwent KT after dialysis treatment (mean period of dialysis, 368.7±4,41.8 days). The mean donor age (50 living-related [83.3%], 10 deceased [16.7%]) was 40.0±12.85 years and the male:female ratio was 1.07:1. The most common cause of ESRD was chronic glomerulonephritis. The overall survival rates at 1, 3, and 5 years after KT were 98%, 98%, and 96%, respectively, while the graft survival rates at 1, 3, and 5 years were 93%, 86%, and 68%, respectively. Children who underwent KT before 10 years of age had better monthly growth rates than those who underwent KT later than 10 years of age. Conclusions KT is performed less frequently in children than in adults, but causes of ESRD vary and clinical outcomes after KT greatly affect the growth and development of pediatric patients. Therefore, further analysis and monitoring of clinical progression after KT in pediatric ESRD patients are necessary.

Background/Aims: Children with chronic kidney disease (CKD) have a high risk of cardiovascular disease. Left-ventricular (LV) hypertrophy (LVH) is an early marker of cardiovascular disease in pediatric CKD, and the prevalence of LVH in pediatric CKD is approximately 20-30% in pre-dialysis CKD patients. However, there is no consensus on the ideal method of defining LVH in pediatric CKD patients. Previous studies have typically used the LV mass index (LVMI), which is calculated as LV mass in grams divided by height in meters to the 2.7th power ≥ 38 g/m2.7, to diagnose LVH in children with CKD. Recently, age-specific reference values for LVMI ≥ 95th percentile and LV wall-thickness z-score > 1.64 in children were addressed. The aim of this study was to assess the prevalence and contributing factors of LVH in pediatric CKD patients according to each measurement and evaluate the concordance between each measurement. Methods: We used the baseline data of the KoreaN cohort study for Outcome in patients With Pediatric Chronic Kidney Disease (KNOW-Ped CKD), which is a nationwide, 10-year, prospective, observational cohort study of pediatric CKD. A total of 469 patients were enrolled, and 458 patients were included in the final analysis. Univariate and multiple logistic regression analysis were performed to evaluate the association of the variables with LVH. Kappa statistics were used to analyze the concordance. Results: According to an LVH diagnosis of LVMI ≥ 38 g/m2.7, 188 patients (41.0%) were diagnosed with LVH, and the prevalence of LVH was high in younger patients (< 2 years of age). Using the age-specific reference values, 116 patients (25.3%) were diagnosed with LVH, and there was no difference in the prevalence of LVH according to age. Thirty-one patients (6.8%) were diagnosed with LVH using an LV wall-thickness z-score > 1.64. There is poor concordance between the diagnosis of LVH using the LV wall-thickness z-score and the LVMI method. Conclusions: The results of this study show that there is poor concordance between the diagnosis of LVH using the wall-thickness z-score and the LVMI2.7 criteria. Further investigation is needed to estimate the correlation between LVH and cardiac dysfunction and to find a better method for defining LVH in the pediatric CKD cohort and thereby predicting cardiac dysfunction.

Purpose Febrile urinary tract infection (UTI) is one of the commonest bacterial infections in children. The purpose of this study is to investigate the clinical characteristics of the first episode of febrile UTI occurring in children over 5 years compared to those in infants younger than a year. Methods We retrospectively reviewed the medical records of 10 patients over 5 years, having febrile UTI, and 25 controls under 1 year. Clinical characteristics including symptoms at admission, the time interval between symptom onset and hospital visit and/or diagnosis, duration of fever, urinalysis, and other laboratory and imaging test results were compared between the two groups. Results Most patients in the control group showed only high fever at the time of presentation to the hospital. However, 60% of the case group had fever along with gastrointestinal (GI) symptoms such as abdominal and flank pain, vomiting, as well as relatively mild pyuria. The case group showed a longer duration between symptom onset and hospital visit and/or diagnosis. Conclusions Delay in diagnosis and initiation of treatment of UTI increases the risk of permanent renal scarring and associated complications. Therefore, early diagnosis and treatment of febrile UTI is vital for very young infants, as well as children considering that febrile UTI could be an important cause of febrile illness in children over 5 years.

Purpose Nocturnal enuresis (NE) is one of the most common problems in childhood. NE has a multifactorial etiology and is influenced by sleep and arousal mechanisms. The aim of the present study was to prospectively evaluate sleep problems and patterns in children with NE compared with normal healthy controls. Methods Twenty-eight children with NE and 16 healthy controls were included in the study. To evaluate sleep habits and disturbances, parents and children filled out a questionnaire that included items about sleep patterns and sleep-related behaviors prior to treatment for NE. Demographic factors and other data were compared for the two groups based on the responses to the sleep questionnaire. Results Night awakening, sleepwalking, and periodic limb movements were more prevalent in children with NE, but symptoms of sleep-disordered breathing were not increased in this group. There were statistically significant differences in periodic limb movements and daytime sleepiness between the two groups. Conclusion Children with NE seemed to have more sleep problems such as night awakening, sleepwalking, and periodic limb movements. In addition, a higher level of daytime sleepiness and hyperactivity in patients with NE suggested a relationship between NE and sleep disorders.

There are two pathogenic models of renovascular hypertension (RVH) originating from renal artery stenosis. We noted a case of a boy who had severe hypertension with atrophic left kidney, hypertrophic right kidney, a segmental stricture of the abdominal aorta, and total occlusion of the right renal artery. Due to the atrophic change of the contralateral, unclipped left kidney, this patient presented with various clinical manifestations related to both models of pathogenesis of RVH occurring at the same time. We conclude that this patient presented with the middle stage of the two RVH pathogenetic models, so called the ‘one-clip, one and half-kidney model.’

PurposeThe use of a 12-week steroid regimen (long-term therapy, LT) for the first episode of idiopathic nephrotic syndrome (NS) reportedly induces a more sustained remission and lower relapse rate than previous regimens, including an 8-week steroid regimen (short-term therapy, ST). Here, we assessed the potential for selective application of 2 steroid regimens (LT vs. ST) based on the days to remission (early responders [ER] vs. late responders [LR]) for the first idiopathic NS episode in children.MethodsPatients were divided into 4 subgroups (ST+ER, ST+LR, LT+ER, and LT+LR) according to the initial steroid regimen used and rapidity of response; the baseline characteristics, relapse rates, and cumulative percentage of children with sustained remission were then compared among the 4 subgroups.ResultsFifty-four children received ST, and the remaining 45 children received LT. As observed in previous studies, children receiving LT showed significantly lower relapse rates during the first year after the first NS episode than those receiving ST. The ST+ER group showed significantly lower relapse rates during the first one year and two years after the first NS episode than the the ST+LR group, whereas there were no significant differences of the relapse rates and duration to the first relapse between the ST+ER and LT+ER groups.ConclusionWe suggest that the initial steroid regimen in idiopathic NS patients can be shortened according to the duration to remission i.e., LT in patients achieving remission after the first week of steroid therapy, and ST in those achieving remission within the first week of steroid therapy.

A 15-year-old boy, who was diagnosed with Alport syndrome and end-stage renal disease, received a renal transplant from a living-related donor. On postoperative day 1, his daily urine output was 10,000 mL despite normal graft function. His laboratory findings including urine, serum osmolality, and antidiuretic hormone levels showed signs similar to central diabetes insipidus, so he was administered desmopressin acetate nasal spray. After administering the desmopressin, urine specific gravity and osmolality increased abruptly, and daily urine output declined to the normal range. The desmopressin acetate was tapered gradually and discontinued 3 months later. Graft function was good, and urine output was maintained within the normal range without desmopressin 20 months after the transplantation. We present a case of a massive polyuria due to transient deficiency of antidiuretic hormone with the necessity of desmopressin therapy immediately after kidney transplantation in a pediatric patient.

PurposeAdult Korean patients on chronic dialysis have a 9-year survival rate of 50%, with cardiovascular problems being the most significant cause of death. The 2011 annual report of the North American Pediatric Renal Trials and Collaborative Studies group reported 3-year survival rates of 93.4% and relatively poorer survival in younger patients.MethodsIn this study, we have reviewed data from Korean Pediatric Chronic Kidney Disease Registry from 2002 to 2010 to assess survival rates and causes of death in Korean children on chronic dialysis.ResultsThe overall estimated patient survival rates were 98.4%, 94.4%, and 92.1% at 1, 3, and 5 years, respectively. No significant difference was observed in survival rates between patients on peritoneal dialysis and those on hemodialysis. Patients for whom dialysis was initiated before 2 years of age (n=40) had significantly lower survival rates than those for whom dialysis was initiated at 6-11 years of age (n=140). In all, 26 patients had died; the mortality rate was 19.9 per 1,000 patient years. The most common causes of death were infections and comorbidities such as malignancy and central nervous system (CNS) or liver diseases.ConclusionThe outcomes observed in this study were better than those observed in adults and comparable to those observed in pediatric studies in other countries. To improve the outcomes of children on chronic dialysis, it is necessary to prevent dialysis-related complications such as infection, congestive heart failure, or CNS hemorrhage and best control treatable comorbidities.

Background: Immunoglobulin A nephropathy (IgAN) and thin glomerular basement membrane nephropathy (TBMN) are the most common causes of persistent hematuria during childhood. The objective of this study is to determine the difference in clinical features and laboratory findings between pediatric patients with IgA deposited TBMN and IgAN alone. Methods: Between January 2000 and March 2009, 95 children were diagnosed with IgAN by renal biopsy. Clinical features and laboratory findings of patients with isolated IgAN and with IgAN plus TBMN were compared; the children diagnosed with IgAN were compared to 127 children who had been diagnosed with TBMN alone during the same period. Results: There were 71 (74.7%) of a total 95 patients that were diagnosed with isolated IgAN (Group1); in 24 (25.3%) of the 95 patients IgAN was combined with TBMN (Group 2). There was marked difference in the gender distribution between Group 2 and isolated TBMN patients. The degree of proteinuria and pathologic severity was higher in Group 1 compared with Group 2. Gross hematuria was present in both groups. There were no distinguishing features in the other laboratory parameters. Conclusion: Patients with both IgAN and TBMN seem to have similar clinical features to patients with isolated IgAN; however, the latter tend to have better pathologic and laboratory findings, compared to the patients with IgAN alone.

Quality of life in addition to various medical problems in children with end-stage renal disease (ESRD) should be objectively assessed to accomplish normal growth and development during childhood. However, unfortunately, studies of quality of life (QoL) in children with ESRD have been not popular yet and there are only fewer suitable assessment tools compared with adults. Recently, disease-specific modules to evaluate QoL in children with chronic disease such as ESRD have been developed. This review was made to introduce these QoL instruments for children and help the clinical application of them.

Polyclonal gammopathy represents the diffuse activation of B cells and is usually related to inflammation or immune-related diseases. However, the mechanisms leading to polyclonal gammopathy are essentially speculative. Generally, infectious, inflammatory, or various other reactive processes may be indicated by the presence of a broad-based peak or band in the gamma region on serum protein electrophoresis results. A 15-year-old girl, who had been receiving peritoneal dialysis, presented with polyclonal gammopathy and massive gross hematuria. Renal artery embolization was performed, after which the continuous bleeding subsided and albumin-globulin dissociation resolved. This is a rare case of polyclonal gammopathy related to renal bleeding.

A 13-year-old girl was diagnosed with non-cystic fibrosis (CF)-related multifocal bronchiectasis accompanied by nephrotic-range proteinuria of unknown cause. On renal biopsy, there were many segmental homogeneous deposits of amyloid tissue with positive Congo red staining in the glomeruli and interstitium. On electron microscopy, relatively straight, non-branching, randomly arranged amyloid fibrils were showed in the mesangium of the glomeruli. These fibrils were approximately 10 nm in diameter, compatible with secondary amyloidosis. Her level of serum amyloid A was remarkably elevated. To our knowledge, this girl is the first case of secondary renal amyloidosis induced by bronchiectasis in Korean children.

Renal fibrosis, characterized by tubulointerstitial fibrosis and glomerulosclerosis, is the final manifestation of chronic kidney disease. Renal fibrosis is characterized by an excessive accumulation and deposition of extracellular matrix components. This pathologic result usually originates from both underlying complicated cellular activities such as epithelial-to-mesenchymal transition, fibroblast activation, monocyte/macrophage infiltration, and cellular apoptosis and the activation of signaling molecules such as transforming growth factor beta and angiotensin II. However, because the pathogenesis of renal fibrosis is extremely complicated and our knowledge regarding this condition is still limited, further studies are needed.

Rituximab (RTX), anti-CD20 monoclonal antibody, has been proposed as a rescue therapy for refractory nephrotic syndrome (NS) on the basis of favorable clinical observations. While reported efficacy of RTX on refractory RTX is promising, the long-term effect obtained from randomized clinical trial is limited, let alone the long-term safety profile of RTX in these patients. To obtain solid evidence of efficacy and safety of this medication, we conducted a clinical trial to evaluate the efficacy and safety of RTX in children with refractory NS. Here we report the interim result. Methods: A multicenter open-label trial was performed in Korean pediatric patients, a single-arm study for steroid and calcineurin inhibitor (CNI) resistant (resistant NS, RNS), and a randomized controlled trial for steroid and CNI-dependent NS (dependent NS, DNS) patients. Eight major centers of Korea participated in this trial. Patients received a single dose of intravenous RTX (375 mg/m2) and efficacy was monitored by clinical response and CD19 cell count. Primary end point was rate of remission achievement for RNS and maintenance of remission for DNS at 6 months after treatment. Steroid and CNI were slowly tapered as scheduled if remission was achieved. Results: Nineteen patients (mean age 9.2±4.7 years) with RNS were enrolled and seven patients achieved complete remission after RTX treatment (remission rate 36.8%). Fifty-three children (mean age 13.0±4.9 years) with DNS were included and randomized to standard treatment or RTX (2:1). At six months after treatment, the remission rates were 77.1% in RTX arm (n=35) and 38.9% in standard therapy arm (n=18). The mean durations of remission maintenance were 5.2 months under slow-tapering standard therapy arm and undetermined in RTX arm. Twenty four patients (44.4% of 54 patients) experienced mild and transient infusion reaction during RTX administration. However, no serious side effect was observed. Conclusions: In this interim analysis of clinical trial to evaluate the efficacy and safety of RTX in children with refractory NS, RTX treatment for refractory NS was safe and effective, especially in patients with DNS.

To evaluate the mineral and bone disorders in children with chronic kidney disease (CKD) stage I to V predialysis. Methods: Pediatric subcohort of KNOW-CKD (KoreaN cohort study for Outcome in patients With CKD) enrolled children (younger than 20 years) with CKD stage I-V (pre-dialysis) from five major pediatric nephrology centers in Korea and collected medical data associated with CKD-mineral and bone disorder. Results: Total number of 300 patients (male:female=199:101) was included in this study. Serum phosphorus (mean ± standard deviation 4.89±0.75, 4.6±0.83, 4.63±0.85, 5.13±1.37, 5.35±1.2 from CKD stage I to V, p=0.0002), fibroblast growth factor (FGF)-23 (32.29±42.04, 41.33±41.00, 70.68±121.06, 67.9±66.95, 121.74±139.36, p=0.0030) and the prevalence of hyperphosphatemia (8.51%, 10.64%, 25.53%, 25.53%, 29.79%, p=0.010) increased as CKD progressed. Intact parathyroid hormone (iPTH) increased (40.84±40.37, 44.13±20.2, 78.93±65.21, 181.39±183.86, 313.85±324.95, p