Asymptomatic hematuria in children: Korean Society of Pediatric Nephrology recommendations for diagnosis and management.

Hematuria is a relatively common condition among school-aged children. Because international guidelines for asymptomatic hematuria in children are unavailable, developing practical guidelines for the diagnosis and management of asymptomatic hematuria based on scientific evidence while considering real-world practice settings, values, and patient and physician preferences is essential. The Korean Society of Pediatric Nephrology developed clinical guidelines to address key questions regarding the diagnosis and management of asymptomatic hematuria in children.

Genotype-phenotype correlations in children with Gitelman syndrome.

BACKGROUND: This study aimed to analyze genotype-phenotype correlations in children with Gitelman syndrome (GS). METHODS: This multicenter retrospective study included 50 Korean children diagnosed with SLC12A3 variants in one or both alleles and the typical laboratory findings of GS. Genetic testing was performed using the Sanger sequencing except for one patient. RESULTS: The median age at the diagnosis was 10.5 years (interquartile range, 6.8;14.1), and 41 patients were followed up for a median duration of 5.4 years (interquartile range, 4.1;9.6). A total of 30 different SLC12A3 variants were identified. Of the patients, 34 (68%) had biallelic variants, and 16 (32%) had monoallelic variants on examination. Among the patients with biallelic variants, those (n = 12) with the truncating variants in one or both alleles had lower serum chloride levels (92.2 ± 3.2 vs. 96.5 ± 3.8 mMol/L, P = 0.002) at onset, as well as lower serum potassium levels (3.0 ± 0.4 vs. 3.4 ± 0.3 mMol/L, P = 0.016), and lower serum chloride levels (96.1 ± 1.9 vs. 98.3 ± 3.0 mMol/L, P = 0.049) during follow-up than those without truncating variants (n = 22). Patients with monoallelic variants on examination showed similar phenotypes and treatment responsiveness to those with biallelic variants. CONCLUSIONS: Patients with GS who had truncating variants in one or both alleles had more severe electrolyte abnormalities than those without truncating variants. Patients with GS who had monoallelic SLC12A3 variants on examination had almost the same phenotypes, response to treatment, and long-term prognosis as those with biallelic variants.

Longitudinal progression trajectory of estimated glomerular filtration rate in children with chronic kidney disease: results from the KNOW-Ped CKD (KoreaN cohort study for Outcomes in patients With Pediatric Chronic Kidney Disease).

Background: 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.

Etanercept treatment for pediatric toxic epidermal necrolysis induced by deflazacort: a case report and literature review.

Toxic epidermal necrolysis (TEN) is a life-threatening mucocutaneous disorder commonly caused by drugs. TEN is often treated with corticosteroids, intravenous immunoglobulin (IVIG), or cyclosporine; however, the efficacy of these treatments is controversial. Etanercept (a TNF-α antagonist) was proven to decrease skin-healing time in a randomized clinical trial. Herein, we report the case of a 44-month-old boy who developed TEN due to deflazacort as the probable culprit drug and was successfully treated with etanercept. The patient presented to the emergency department complaining of erythematous maculopapular rashes and vesicles all over the face and body, with vesicles on the hands, feet, and trunk. Symptoms started 4 days before presentation, with edema of the upper lip, which progressed to erythematous macules over the body. He was started on deflazacort for nephrotic syndrome 21 days before the visit. Approximately 20% of the body surface area (BSA) was covered by vesicular lesions. Under the diagnosis of Steven Johnson syndrome/TEN, deflazacort was discontinued, and intravenous dexamethasone (1.5 mg/kg/day), a 5-day course of IVIG (0.4 mg/kg/day), and cyclosporine (3 mg/kg/day) were administered. The lesions seemed to be stationary for 3 days, but on the 6th day of hospitalization, when IVIG was discontinued, the vesicular lesions progressed to approximately 60% of the BSA. Etanercept 0.8 mg/kg was administered subcutaneously. Lesions stopped progressing, and bullous lesions started epithelialization. However, on the 15th day, around 30% of the BSA was still involved; thus, a second dose of etanercept was administered. No acute or sub-acute complications were observed. In conclusion, the use of etanercept in children with TEN that is not controlled with conventional therapy is both effective and safe.

Outcome of immunosuppression in children with IgA vasculitis-related nephritis.

BACKGROUND AND HYPOTHESIS: IgA vasculitis with nephritis (IgAVN) is the most common vasculitis in children. Treatment recommendations are, due to a lack of evidence, based on expert opinion resulting in variation. The aim of this study was to describe clinical presentation, treatment and outcome of an extremely large cohort of children with biopsy proven IgAVN to identify prognostic risk factors and signals of treatment efficacy. METHODS: Retrospective data were collected on 1148 children with biopsy proven IgAVN between 2005 and 2019 from 41 international paediatric nephrology centres across 25 countries and analyzed using multivariate analysis. The primary outcome was estimated glomerular filtration rate (eGFR) and persistent proteinuria at last follow up. RESULTS: The median follow up was 3.7 years (IQR 2-6.2). At last follow up, 29% of patients had an eGFR < 90 ml/min/1.73m2, 36% had proteinuria and 3% had chronic kidney disease stage 4-5. Older age, lower eGFR at onset, hypertension and histological features of tubular atrophy and segmental sclerosis were predictors of poor outcome. There was no evidence to support any specific second line immunosuppressive regimen to be superior to others, even when further analysing subgroups of children with reduced kidney function, nephrotic syndrome or hypoalbuminemia at onset. Delayed start of immunosuppressive treatment was associated with a lower eGFR at last follow up. CONCLUSION: In this large retrospective cohort, key features associated with disease outcome are highlighted. Importantly there was no evidence to support that any specific immunosuppressive treatments were superior to others. Further discovery science and well-conducted clinical trials are needed to define accurate treatment and improve outcomes of IgAVN.

Development of a tool for predicting HNF1B mutations in children and young adults with congenital anomalies of the kidneys and urinary tract.

BACKGROUND: We aimed to develop a tool for predicting HNF1B mutations in children with congenital abnormalities of the kidneys and urinary tract (CAKUT). METHODS: The clinical and laboratory data from 234 children and young adults with known HNF1B mutation status were collected and analyzed retrospectively. All subjects were randomly divided into a training (70%) and a validation set (30%). A random forest model was constructed to predict HNF1B mutations. The recursive feature elimination algorithm was used for feature selection for the model, and receiver operating characteristic curve statistics was used to verify its predictive effect. RESULTS: A total of 213 patients were analyzed, including HNF1B-positive (mut + , n = 109) and HNF1B-negative (mut - , n = 104) subjects. The majority of patients had mild chronic kidney disease. Kidney phenotype was similar between groups, but bilateral kidney anomalies were more frequent in the mut + group. Hypomagnesemia and hypermagnesuria were the most common abnormalities in mut + patients and were highly selective of HNF1B. Hypomagnesemia based on age-appropriate norms had a better discriminatory value than the age-independent cutoff of 0.7 mmol/l. Pancreatic anomalies were almost exclusively found in mut + patients. No subjects had hypokalemia; the mean serum potassium level was lower in the HNF1B cohort. The abovementioned, discriminative parameters were selected for the model, which showed a good performance (area under the curve: 0.85; sensitivity of 93.67%, specificity of 73.57%). A corresponding calculator was developed for use and validation. CONCLUSIONS: This study developed a simple tool for predicting HNF1B mutations in children and young adults with CAKUT.

Efficacy and safety of long-term repeated use of rituximab in pediatric patients with nephrotic syndrome.

BACKGROUND: We aimed to investigate the efficacy and safety of repeated use of rituximab (RTX) in pediatric patients with nephrotic syndrome (NS). METHODS: Retrospective review of 50 patients with steroid-dependent NS (SDNS) who had received more than three cycles of RTX was conducted; each consisted of one to four infusions until B lymphocytes were depleted. RESULTS: The median age of starting the first RTX cycle was 12.4 years (interquartile ranges (IQR) 10.2-14.6). During a median follow-up period of 6.3 (IQR 3.6-8.6) years, patients received a median of 5.0 RTX cycles (IQR 4.0-7.3). The number of relapses decreased from a median of 2.0 relapses per year (IQR 1.0-3.0) to 0.2 relapses per year (IQR 0.0-0.5) after long-term RTX treatments (P < 0.001). Longer relapse-free periods were associated with more than four RTX cycles, longer B-cell depletion, older age at each RTX treatment, and lower cholesterol levels. B lymphocytes recovered to 1% at a median of 5.9 months (95% confidence interval 5.7-6.1) after RTX administration. Factors related to a longer period of B-cell depletion included more than five RTX cycles, a higher dose of RTX, older age at treatment, and concurrent use of antimetabolites. During repeated RTX treatments, 8.0%, 6.0%, and 2.0% of patients developed hypogammaglobulinemia, severe infection, and severe neutropenia, respectively. CONCLUSIONS: Long-term repeated use of RTX may be effective and safe in pediatric NS patients. Furthermore, the redosing of RTX could be chosen by considering predictive factors for relapse-free and B-cell depletion periods.

Safety of BNT162b2 mRNA COVID-19 vaccine in children with chronic kidney disease: a national population study from South Korea.

BACKGROUND: In South Korea, COVID-19 vaccination has been recommended to adolescents aged 12 - 17 since October, 2021. We aimed to assess the rate of adverse events following COVID-19 vaccination in adolescents with chronic kidney disease (CKD) in South Korea, using national cohort data. METHODS: We retrieved the clinical information of adolescents 12 - 17 years old from the Korea Disease Control and Prevention Agency-COVID19-National Health Insurance Service (K-COV-N) database, to calculate incidence rates of purpura and other hemorrhagic conditions, Guillain-Barré syndrome (GBS), Kawasaki disease/multisystem inflammatory syndrome in children (MIS-C), myocarditis and/or pericarditis, and anaphylaxis in adolescents with CKD, after BNT162b2 vaccination. RESULTS: Among the 2306 adolescents with CKD, 62.7% (n = 1446) had received the BNT-162b2 vaccine. GBS, Kawasaki disease/MIS-C, and anaphylaxis or anaphylactic shock did not occur during the observation period. Purpura and hemorrhagic conditions were more frequent in the unvaccinated group (7/860 vs. 1/1446), while myocarditis/pericarditis was observed only in the vaccinated group (0/860 vs. 1/1446). Adjusted odds ratio for any of the two adverse events was lower in vaccinated adolescents than in the unvaccinated group which did not reach statistical significance (adjusted odds ratio = 0.14, 95% confidence interval: 0.02, 1.16, P = 0.068). CONCLUSIONS: In this national cohort study of adolescents with CKD in South Korea, we observed no evidence of increased risk of adverse events following BNT162b2 vaccination. Our finding offers insights into the safety of COVID-19 vaccines, empowering adolescent patients with CKD and their caregivers to make informed decisions.

Effect of donor-recipient size mismatch on long-term graft survival in pediatric kidney transplantation: a multicenter cohort study.

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.

Long-term outcomes and associated prognostic risk factors of childhood-onset lupus nephritis.

Background: This study investigated the clinical characteristics and kidney outcomes of childhood-onset lupus nephritis (LN), and risk factors associated with prognosis. Methods: We enrolled 216 patients with histologically diagnosed LN during childhood. The Korean Society of Pediatric Nephrology organized a retrospective cohort study of childhood-onset LN in 13 major pediatric nephrology centers in South Korea. Results: The mean age at kidney biopsy was 13.2 ± 3.22 years. The main forms of presentation were nephrotic syndrome and/or hematuria in 152 patients (70.4%), and the most common histological finding was World Health Organization (WHO) class IV in 138 patients (63.9%), followed by WHO class III in 34 patients (15.7%). In the outcome analysis, the mean follow-up period of the patients was 7.8 ± 5.11 years. At last follow-up, 32 patients (14.8%) developed advanced chronic kidney disease (CKD). Male sex and failure to achieve remission at 12 months of treatment were significant risk factors for developing advanced CKD (hazard ratio of 2.57 and 2.29, respectively). Conclusion: Our study demonstrated the clinical characteristics and long-term outcomes of patients with childhood-onset LN. Male sex and failure to achieve remission in the first year of treatment were predictive of advanced CKD. Therefore, prompt awareness and close monitoring of these high-risk patients are needed, which may further improve the prognosis of children with LN.

Regional Variation in Hemoglobin Distribution Among Individuals With CKD: the ISN International Network of CKD Cohorts.

Introduction: Despite recognized geographic and sex-based differences in hemoglobin in the general population, these factors are typically ignored in patients with chronic kidney disease (CKD) in whom a single therapeutic range for hemoglobin is recommended. We sought to compare the distribution of hemoglobin across international nondialysis CKD populations and evaluate predictors of hemoglobin. Methods: In this cross-sectional study, hemoglobin distribution was evaluated in each cohort overall and stratified by sex and estimated glomerular filtration rate (eGFR). Relationships between candidate predictors and hemoglobin were assessed from linear regression models in each cohort. Estimates were subsequently pooled in a random effects model. Results: A total of 58,613 participants from 21 adult cohorts (median eGFR range of 17-49 ml/min) and 3 pediatric cohorts (median eGFR range of 26-45 ml/min) were included with broad geographic representation. Hemoglobin values varied substantially among the cohorts, overall and within eGFR categories, with particularly low mean hemoglobin observed in women from Asian and African cohorts. Across the eGFR range, women had a lower hemoglobin compared to men, even at an eGFR of 15 ml/min (mean difference 5.3 g/l, 95% confidence interval [CI] 3.7-6.9). Lower eGFR, female sex, older age, lower body mass index, and diabetic kidney disease were all independent predictors of a lower hemoglobin value; however, this only explained a minority of variance (R2 7%-44% across cohorts). Conclusion: There are substantial regional differences in hemoglobin distribution among individuals with CKD, and the majority of variance is unexplained by demographics, eGFR, or comorbidities. These findings call for a renewed interest in improving our understanding of hemoglobin determinants in specific CKD populations.

Clinical outcomes of nephrocalcinosis in preschool-age children: association between nephrocalcinosis improvement and long-term kidney function.

Background: We evaluated the long-term clinical outcomes of nephrocalcinosis (NC) according to etiology and grade in preschool-age children with NC. Methods: We retrospectively analyzed the clinical outcomes and disease grade of children with NC classified into three groups according to etiology: prematurity, tubular disorders, and others. Results: Overall, 67 children were diagnosed with NC [median age, 0.76 years; interquartile range (IQR) 0.46-2.14 years]. The etiologies of NC included prematurity (28.4%), tubular disorders (25.4%), and others (46.3%). Moreover, 56 (83.6%) children were asymptomatic and diagnosed accidentally through kidney ultrasonography. Newly diagnosed underlying diseases were greater in the tubular disorders group than in the other two groups (P = 0.001). Significantly more newly diagnosed NCs were grade 3 than grade 1 (P = 0.003). The median estimated glomerular filtration rate (eGFR) changed from 96.1 (IQR 68.8-119.2) ml/min/1.72 m2 at diagnosis to 90.9 (IQR 76.4-106.4) ml/min/1.72 m2 at the last follow-up, without a significant difference (P = 0.096). Changes in the kidney function did not differ according to etiology. However, patients without improvement in NC grade showed a decrease in eGFR from 98.1 (IQR 71.1-132.9) to 87.4 (IQR 74.0-104.1) ml/min/1.73 m2 (P = 0.023), while patients with improved NC grade did not show any change in the kidney function. Conclusions: Early recognition, especially in NC grade 3, can help uncover further diagnoses, such as tubular disorders. Long-term kidney function depends on whether the NC grade improves.

Clinical course of post-kidney transplant Schimke immuno-osseous dysplasia.

BACKGROUND: Schimke immuno-osseous dysplasia (SIOD) is a rare systemic disease characterized by short stature, proteinuria, and recurrent infections. Patients usually have spondyloepiphyseal dysplasia, and progressive steroid-resistant nephropathy that leads to kidney failure. However, their clinical course after kidney transplantation (KT) is not yet well known. Here, we present our experience with cases of SIOD treated at our institute. CASE PRESENTATION: Since 2014, three children have been diagnosed with nephropathy resulting from SIOD. They presented with proteinuria in the nephrotic range at 7, 5, and 3 years of age. Focal segmental glomerulosclerosis was confirmed and progressed to kidney failure approximately 2 years after proteinuria was detected. These patients underwent living-donor KT from their parents. After KT, Case 1 lost his graft within 7 months due to multi-organ failure caused by disseminated adenovirus infection and died. Case 2 experienced graft failure 5 years after KT due to acute rejection from poor compliance. In Case 3, the allograft was still functioning 6 years after KT with low-dose tacrolimus single medication (trough level < 5 ng/mL). Extra-renal manifestations progressed regardless of KT, namely, right renal vein thrombosis and pulmonary hypertension in Case 1, severe bilateral hip dysplasia and Moyamoya syndrome in Case 2, and neutropenia and thrombocytopenia in Case 3, in addition to recurrent infection. CONCLUSION: In SIOD patients, KT is complicated with recurrent infections due to their inherent immune dysfunction. Additionally, extra-renal symptoms may render the patients morbid despite the recovery of kidney function.

Gastrointestinal involvement of passenger lymphocyte syndrome followed by minor ABO-incompatible renal transplantation: A case report.

BACKGROUND: People with group O blood are considered universal organ donors compatible with any other blood group. However, in the case of minor ABO-incompatible transplantation, immune-mediated hemolysis may occur due to concomitant transfer of donor B lymphocytes together with the allograft. These passenger lymphocytes can produce antibodies in the recipients erythrocytes, causing hemolytic anemia known as passenger lymphocyte syndrome (PLS). METHODS: A retrospective chart review was performed. RESULTS: A 6-year-old boy (A+) underwent transplantation of a kidney from his father (O+). On postoperative day (POD) 6, the patient developed fever with no explainable causes. On POD 11, he presented with abdominal pain, hematochezia, and severe diarrhea, with sudden hemolytic anemia. Since then, GI symptoms have continued. On POD 20, direct antiglobulin test (DAT) was positive, and the anti-A IgM/G titer was 2/32. The results of the anti-A antibody elution test were strongly positive (3+). These findings highly suggested PLS. On the same day, the GI symptoms suddenly worsened, and laboratory findings showed hemolysis and thrombocytopenia with disseminated intravascular coagulation (DIC). Abdominal computed tomography (CT) scans suggested ischemic colitis of venous origin, and the patient underwent segmental colectomy with ileostomy formation on POD 23. To remove the anti-A antibodies, the patient underwent therapeutic plasma exchange (TPE) five times until the DAT and anti-A elution test were negative. CONCLUSIONS: We report a case of gastrointestinal involvement of PLS that occurred after minor ABO-incompatible kidney transplantation. This is the first report of ischemic colitis as an atypical manifestation of PLS.

Corrigendum: Mineral bone disorder in children with chronic kidney disease: data from the KNOW-Ped CKD (Korean cohort study for outcome in patients with pediatric chronic kidney disease) study.

[This corrects the article DOI: 10.3389/fped.2023.994979.].

Corrigendum: Long-term outcome of Bartter syndrome in 54 patients: a multicenter study in Korea.

[This corrects the article DOI: 10.3389/fmed.2023.1099840.].

Association between serum total cholesterol and chronic kidney disease progression in children: results from the KNOW-PedCKD.

BACKGROUND: Dyslipidemia can cause cardiovascular disease and increase the fatality rate among children with chronic kidney disease (CKD); this makes early screening and treatment of dyslipidemia crucial. This study aimed to assess the association between the changes in serum total cholesterol levels over time and the degree of CKD progression in children. METHODS: From April 2011 to August 2021, 379 of the 432 participants enrolled in the KoreaN cohort study for Outcomes in patients With Pediatric CKD (KNOW-PedCKD) were included and divided into 4 categories based on total cholesterol levels (< 170 mg/dL, acceptable; 170-199, borderline; 200-239, high; and ≥ 240, very high). Survival analysis using conventional and time-dependent Cox proportional hazards model were performed for a composite event of CKD progression (≥ 50% decrease in estimated glomerular filtration rate from baseline, a twofold increase in creatinine, or the occurrence of dialysis or kidney transplantation). RESULT: The incidence of composite event of CKD progression was 96.3, 90.4, 87.3, and 270.6 cases per 1000 person-years in the acceptable, borderline, high, and very high categories, respectively. On using the time-dependent Cox proportional hazards model, the hazard ratio of the very high category was significantly higher than that of the acceptable category by 3.13 times as per univariate analysis and 2.37 times as per multivariate analysis. CONCLUSIONS: Very high serum total cholesterol is a significant risk factor for CKD progression in children. Lowering total cholesterol levels below the very high category in children with CKD may delay the progression of CKD. A higher resolution version of the Graphical abstract is available as Supplementary information.

Genotype-phenotype correlation of X-linked Alport syndrome observed in both genders: a multicenter study in South Korea.

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 < 0.001, hazard ratio (HR) 2.8) and splicing and truncating groups (P = 0.002, HR 3.1). Sensorineural hearing loss was detected in 65.1% of male patients, while hearing survival periods showed a highly significant difference between the non-truncating and truncating groups (P < 0.001, HR 5.1). In female patients, approximately 20% developed kidney failure at the median age of 50.2 years. The kidney survival was significantly different between the non-truncating and truncating groups (P = 0.006, HR 5.7). Our findings support the presence of genotype-phenotype correlation not only in male patients but also in female patients with XLAS.

Contrast-enhanced ultrasound for the diagnosis of acute pyelonephritis in pediatric patients with urinary tract infection: A feasibility study.

PURPOSE: This study aimed to assess the feasibility of contrast-enhanced ultrasound (CEUS) for the diagnosis of acute pyelonephritis (APN) in pediatric patients with febrile urinary tract infection (UTI). MATERIALS AND METHODS: Between March 2019 and January 2021, study participants with suspected UTI were assessed for APN using ultrasound. Parenchymal echogenicity changes, renal pelvis dilatation, and the presence of a focal suspected lesion were assessed using conventional grayscale ultrasound. The presence and location of a decreased perfusion area were evaluated using color Doppler ultrasound (CDUS) and CEUS. Agreement between each ultrasound examination and a 99mTc‒dimercaptosuccinic acid (DMSA) scan was assessed using the κ value, and the most visible period of the lesion was evaluated using CEUS. RESULTS: This study enrolled 21 participants (median age, 8.0 months; range, 2.0-61.0 months) with isolated urinary tract pathogens. Five increased parenchymal echotextures (11.9%) and 14 renal pelvic dilatations (33.3%) were confirmed, but no focal lesions were detected on the grayscale images. CDUS and CEUS showed decreased local perfusion suggestive of APN in two and five kidneys, respectively. DMSA scan showed substantial agreement with CEUS findings (κ = 0.80, P = 0.010), but other grayscale and CDUS findings did not agree with DMSA scan results (P > 0.05). All lesions were best observed in the late parenchymal phase on CEUS. CONCLUSION: CEUS can reveal renal perfusion defects in pediatric patients with suspected APN without radiation exposure or sedation; therefore, CEUS may be a feasible and valuable diagnostic technique.