Despite the many advantages of peritoneal dialysis (PD) in children with end-stage 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.

Hemodialysis is rarely used in neonates and infants due to the risk of major complications in the very young. Nevertheless, there are clinical situations where hemodialysis is needed and may be helpful in small children. Recently, new developments in specialized hemodialysis equipment and specifically trained personnel have made it possible to implement hemodialysis in neonates and infants. In this review, we will discuss hemodialysis for the treatment of small children with renal replacement therapy-requiring conditions, and consider indications, prescriptions, complications, and ethical issues.

Objectives: We aimed to investigate the incidence, manifestations, and outcomes of malignancy after pediatric kidney transplantation (KT) at our center over 30 years. Methods: We retrospectively reviewed the medical records of 155 patients under 18 years of age who underwent KT between January 1990 and February 2020 at Asan Medical Center. Results: Twelve patients (7.7%) were diagnosed with a malignancy after KT. Malignancy was diagnosed after a mean period of 6.4±5.9 years (median 4.6, range 0.5-20.6 years) after KT. Nine (75.0%) of the 12 cancer patients were diagnosed with post-transplant lymphoproliferative disease (PTLD), and the other three had papillary thyroid cancer, mucoepidermoid cancer of the hard palate, and T-cell acute lymphoblastic leukemia, respectively. PTLD was diagnosed within a mean of 3.7±3.4 years (median 3.7, range 0.5-9.8 years) after KT. Five patients diagnosed with PTLD were cured without recurrence. Three patients with PTLD died from the disease, and one patient with mucoepidermoid cancer from a non-PTLD malignancy died after progression, despite surgical resection and chemotherapy. Three (33.3%) of the nine survivors progressed to end-stage renal disease (ESRD) after completing cancer treatment. No patient with post-transplant malignancy (PTM) experienced critical renal deterioration during cancer treatment. Conclusion: PTLD was the most common PTM, occurring at 5.8% of the pediatric KT patients after KT in our center. Careful follow up is needed particularly considering the risk of PTLD after KT in children.

Purpose: To investigate the association between urinary neutrophil gelatinase-associated lipocalin (uNGAL) and leukocyte differential count in children with urinary tract infections (UTIs). Methods: A retrospective chart review was performed in children undergoing uNGAL measurements between June 2018 and September 2019. Patients with suspected or diagnosed UTIs were included. The relationship between uNGAL and blood leukocyte differential count was investigated in children. Results: A total of 197 children were included in this study, 119 of whom (60%) had UTIs. The non-UTI patients (n=78) were diagnosed with pneumonia, acute gastroenteritis, viral upper respiratory infection, and others. After adjusting for age, gender, and fever duration, the leukocyte count, monocyte count, and uNGAL levels were higher in the UTI group than in the non-UTI group (P<0.05). uNGAL showed positive correlations with neutrophil counts, monocyte counts, the neutrophil-to-lymphocyte ratio, and the monocyte-to-lymphocyte ratio in the UTI group (P<0.05). uNGAL levels were only associated with the neutrophil-to-lymphocyte ratio in the non-UTI group (P<0.05). In a multivariable logistic regression analysis, only uNGAL was associated with the presence of UTI (P<0.05). The area under the receiver operating characteristic curves for uNGAL and monocyte counts to identify UTI were 0.89 (95% confidence interval (CI): 0.824-0.939; P=0.025) and 0.7 (95% CI: 0.627-0.774; P=0.038), respectively. Conclusions: In children with UTIs, uNGAL levels may be associated with blood leukocyte differential counts. uNGAL measurements and monocyte counts can be helpful in children with suspected UTIs.

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.

Purpose: The aim of this study is to evaluate the clinical utility of late 6-month dimercapto-succinic acid (DMSA) renal scan in predicting vesicoureteral reflux (VUR) and long-lasting renal scars in children with first acute pyelonephritis (APN). Methods: A retrospective case study of children admitted with APN from January 2010 to July 2017 was performed. The study included patients with voiding cystourethrography (VCUG) and acute and late 6-month DMSA scan. We analyzed the clinical, laboratory and imaging findings of patients with and without late cortical defects at 6 months and those with or without VUR. Results: Among 145 children with APN, 50 (34.5%) had cortical defects on the late DMSA renal scan and 60 (41.4%) showed VUR. Thirteen of 38 (34.2%) children undergoing 18-month DMSA renal scan showed a long-lasting renal scars. Compared with children without late cortical defects, patients with late 6-month cortical defects had a higher incidence of VUR and long-lasting renal scars, and relapse of UTI (all P<0.05). In a multivariable analysis, both high-grade VUR and relapse of UTI were independently correlated with the presence of late 6-month cortical defects (P<0.05). Late cortical defects and relapse of UTI were also associated with the presence of VUR (P<0.05). Only the late 6-mo cortical defects was an independent predictor of long-lasting renal scars in children with APN (P<0.05). Conclusion: An abnormal late 6-month DMSA renal scan may be useful in identifying VUR and long-lasting renal scars in children diagnosed with APN.

Purpose: The purpose of this study was to evaluate the prevalence, clinical characteristics, and long-term clinical effects of hypertension in Korean childhood-onset systemic lupus erythematous (SLE) patients. Methods: The medical records of SLE patients, diagnosed by 2019 SLE European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria, who visited Samsung Medical Center from January 2009 to May 2019 were reviewed. Disease activity and long-term damage were evaluated using the Modified Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) and the Pediatric Systemic Lupus International Collaborating Clinics/ACR Damage Index (Ped-SDI), respectively. The sex-, age- and height-blood pressure standards recommended by the American Academy of Pediatrics 2017 guideline was used to define hypertension. Results: A total of 32 patients were enrolled in this study. The median follow-up duration was 7.3 years and females were predominant. The median ages at SLE and hypertension diagnoses were 14.2 and 14.3 years, respectively. The biopsy-proven lupus nephritis was detected in 90.6% and 37.5% were class IV. During the follow-up, 12 patients (37.5%) had hypertension. Among them, 2 patients had 3 episodes of posterior reversible encephalopathy syndrome and 5 patients had left ventricular hypertrophy (LVH). Univariate analysis showed baseline hypertension was significantly correlated with a lower estimated glomerular filtration rate, higher body mass index and SLEDAI at baseline. The development of hypertension during the follow-up was significantly correlated with obesity, LVH, and higher Ped-SDI. Conclusion: Our study revealed that hypertension in pediatric SLE is associated with obesity and renal function at SLE diagnosis and could affect long-term damage.

Distal renal tubular acidosis (dRTA) is a rare renal tubular disorder characterized by normal anion gap metabolic acidosis, hypokalemia, and high urine pH. It can be inherited or acquired. In untreated pediatric patients with dRTA, rickets and growth retardation are common. We report the case of a 12-year-old Lao girl who presented with typical clinical features of dRTA with severe bone deformities that developed after a bed-ridden state due to a bicycle accident at the age of 8 years. Initial laboratory tests revealed metabolic acidosis with a normal anion gap, hypokalemia, and alkali urine. Renal ultrasonography revealed bilateral medullary nephrocalcinosis. Whole exome sequencing revealed no pathogenic mutations. After treatment with oral alkali, potassium, and vitamin D, she could walk and run. Later, she underwent corrective orthopedic surgeries for bony deformities. Thus, in pediatric dRTA patients, despite severe symptoms remaining untreated, accurate diagnosis and proper management can improve quality of life.

Gorham-Stout syndrome is a rare bone disorder characterized by progressive massive osteolysis and proliferation of vascular and lymphatic vessels. A 15-year-old boy was initially diagnosed with Gorham-Stout at the age of 8 years based on clinical and radiological findings. Following diagnosis, he was treated with pamidronate, interferon alfa, propranolol, oral corticosteroids, and sirolimus. He developed proteinuria at the age of 15 and progressed into the nephrotic range 2 years later. A renal biopsy revealed focal segmental glomerulosclerosis, not otherwise specified variant. The sequential increase in proteinuria associated with medications suggested that the focal segmental glomerulosclerosis may be caused by pamidronate and sirolimus, but cannot completely rule out the possibility of kidney involvement of GSS itself.

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.

Nephrogenic diabetes insipidus (DI) is a rare disease in which the patient cannot concentrate urine despite appropriate or high secretion of antidiuretic hormone. Congenital nephrogenic DI is caused by the arginine vasopressin receptor 2 (AVPR2) or aquaporin 2 (AQP2) gene mutation; the AVPR2 genetic mutation accounts for 90% of the cases. National health screening for infants and children was launched in 2007 in order to prevent accidents and promote public health in infants and children in Korea. The program has been widely used as a primary clinical service in Korea. We treated an infant with faltering growth and delayed development detected by the National health screening program, and diagnosed the problem as nephrogenic DI caused by a rare missense mutation of c.490T>C on the AVPR2 gene. This case can be a good educational nephrogenic DI with a rare AVPR2 mutation, which was well screened and traced by the national health screening program for infants and children in Korea.

Atypical hemolytic uremic syndrome (aHUS) is an extremely rare and life-threatening disorder. Typical HUS is often caused by Shiga toxin-positive Escherichia coli, while aHUS is caused by dysregulation of the alternative pathway of the complement system in association with genetic abnormalities or development of autoantibodies. Eculizumab, a humanized anti-complement 5 monoclonal antibody, is recommended for the treatment of aHUS, but its long-term safety and efficacy in pediatric patients remain under review. In this paper, we report a pediatric case of aHUS with anti-complement factor H autoantibodies, who was treated successfully with eculizumab.