Antenatally detected urinary tract dilatation: a pediatric nephrologist's point of view

Antenatally diagnosed urinary tract dilatation (UTD), previously referred to as antenatal hydronephrosis, is the most commonly detected abnormality by prenatal ultrasonography. Several grading systems have been developed for the classification of antenatal UTD using prenatal and postnatal ultrasonography. UTD comprises a wide variety of congenital abnormalities of the kidney and urinary tract ranging from transient UTD to more significant abnormalities such as vesicoureteral reflux, ureteropelvic junction obstruction, ureterocele, ureterovesical junction obstruction, posterior urethral valves, and non-refluxing megaureter. Optimizing the evaluation of antenatally detected UTD is essential to recognize children with important disorders while avoiding excessive investigations. Conservative approach with close follow-up is increasingly accepted as an appropriate treatment option for patients with asymptomatic vesicoureteral reflux and ureteropelvic junction obstruction in recent years. However, predicting permanent kidney damage in an unselected group of children with antenatal UTD is still challenging. The management and follow-up of children with UTD should be individualized based on recommendations from a pediatric nephrologist, a pediatric urologist, or both. Future research directed at predicting long-term outcomes of children diagnosed with UTD from mild findings to severe disease is needed to refine management for those at higher risk of kidney disease progression

Neutrophil Gelatinase-Associated Lipocalin and Kidney Diseases

Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as one of the most promising biomarkers of renal epithelial injury. Numerous studies have presented the diagnostic and prognostic utility of urinary and plasma NGAL in patients with acute kidney injury, chronic kidney disease, renal injury after kidney transplantation, and other renal diseases. NGAL is a member of the lipocalin family that is abundantly expressed in neutrophils and monocytes/macrophages and is a mediator of the innate immune response. The biological significance of NGAL to hamper bacterial growth by sequestering iron-binding siderophores has been studied in a knock-out mouse model. Besides neutrophils, NGAL is detectable in most tissues normally encountered by microorganisms, and its expression is upregulated in epithelial cells during inflammation. A growing number of studies have supported the clinical utility of NAGL for detecting invasive bacterial infections. Several investigators including our group have reported that measuring NGAL can be used to help predict and manage urinary tract infections and acute pyelonephritis. This article summarizes the biology and pathophysiology of NGAL and reviews studies on the implications of NGAL in various renal diseases from acute kidney injury to acute pyelonephritis

Risk factors for recurrent urinary tract infections in young infants under the age of 24 months

Purpose Recurrent urinary tract infections (UTIs) in children is a major challenge for pediatricians. This study was designed to investigate the risk factors for recurrent UTIs and determine the association between recurrent UTIs and clinical findings, including growth patterns in infants and children younger than 24 months of age. Methods We retrospectively reviewed the medical records of 147 patients <24 months of age with UTIs who were hospitalized between August 2018 and October 2021. The patients were divided into recurrent and single UTI episode groups. Clinical findings and anthropometric and laboratory data were compared between the two groups. Results In the recurrent UTI group, the weight-for-length (WFL) percentile at the first UTI diagnosis was lower compared to the single UTI episode group, and the weight-for-age percentile at 3-month and 6-month follow-ups after the first UTI decreased (all P<0.05). In univariable logistic regression analysis, higher birth weight, lower WFL percentile, the presence of hydronephrosis, acute pyelonephritis or vesicoureteral reflux, the use of prophylactic antibiotics, and non-Escherichia coli infections were associated with the development of recurrent UTIs (all P<0.05). However, in the multivariable analysis, only the presence of hydronephrosis and prophylactic antibiotic use were independently related to UTI recurrence (P<0.05). Conclusions The presence of hydronephrosis at the first UTI can be helpful for predicting UTI recurrence in young children aged <24 months. Antibiotic prophylaxis may be associated with UTI recurrence. Potential growth delay should be carefully monitored in infants with recurrent UTI

Acute Tubular Necrosis associated with the Ketogenic Diet in a Child with Intractable Epilepsy

The ketogenic diet (KD) has been used as an effective antiepileptic therapy for intractable childhood epilepsy. However, various adverse effects have been reported with use of the KD. We report a case of a child who developed acute tubular necrosis subsequent to therapy with KD. A 5-year-old girl had myoclonic epilepsy with developmental delay. She was under the treatment with antiepileptic drugs since the age of 3 months and on the KD during the past 18 months. Proteinuria persisted intermittently with the initiation of the KD and subsequently increased in the past 2 months. She was admitted with intermittent mild fever, vomiting, and lethargy for the past 3–4 weeks. At the time of admission, she presented with hypertriglyceridemia, heavy proteinuria, renal Fanconi syndrome, and acute kidney injury. Renal sonography showed a marked increase in the size and parenchymal echogenicity of both kidneys. A renal biopsy revealed acute tubular necrosis accompanied by early interstitial fibrosis. After the withdrawal of the KD and supportive therapy, without changing other anticonvulsants and their dosages, improvement of renal function was observed. Proteinuria had disappeared after 1 month and kidney size returned to normal after 8 months. It is hypothesized that the KD can induce and/or aggravate the renal tubulointerstitial injury in some patients who are under the treatment with anticonvulsants

Group B Streptococcal Renal Abscess in a 17-Year-Old Girl with Type 1 Diabetes Mellitus

Streptococcus agalactiae or group B streptococcus (GBS) is associated with infections in neonates and pregnant women. Herein, we describe a rare case of GBS renal abscess with peritonitis and pleural effusion in a 17-year-old girl with type 1 diabetes mellitus. The girl was admitted due to fever and right flank pain. Laboratory findings included leukocytosis and increased C-reactive protein level and erythrocyte sedimentation rate. Her serum glucose level was 484 mg/dL. Urinalysis showed no pyuria. Renal sonography revealed parenchymal swelling in the right kidney. The patient was administered intravenous cefotaxime. Urine and blood cultures were negative. Fever seemed to improve, but the following day, she complained of abdominal pain and fever. Antibiotic was switched to imipenem, and abdominal and pelvic CT revealed a ruptured right renal abscess, peritonitis, and bilateral pleural effusion with atelectasis. Pigtail catheter drainage of the abscess was performed. Culture from the abscess was positive for GBS, and fever subsided 2 days after the drainage. She was discharged with oral cefixime. The clinical course of urinary tract infections (UTIs) can be atypical in patients with diabetes, and GBS can be a cause of UTIs. Prompt diagnosis and management are necessary to prevent complications in patients showing atypical courses

Vesicoureteral Reflux and Renal Scarring in Children with Acute Pyelonephritis: the Role of Late 6-month Dimercaptosuccinic Acid Renal Scan

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

A Case of Hypereosinophilic Syndrome with Bladder Involvement in a 7-Year-Old Boy

Hypereosinophilic syndrome (HES) is characterized by the presense of hypereosinophilia with evidence of target organ damage. We report a patient diagnosed with eosinophilic cystitis and HES. A 7 year old boy had hematuria, dysuria, and increased urinary frequency for 1 day. Laboratory examinations revealed hypereosinophilia (eosinophils, 2,058/µL), hematuria, and proteinuria. Abdominal sonography revealed diffuse and severe wall thickening of the bladder. The patient was treated initially with antibiotics. However, his symptoms did not improve after 7 days. A computed tomography scan demonstrated severe wall thickening of the bladder and the hypereosinophilia persisted (eosinophils, 2,985/µL). The patient complained of chest discomfort, dyspnea, epigastric pain, and vomiting on hospital day 10. Parasitic, allergic, malignancy, rheumatologic, and immune workups revealed no abnormal findings. Chest X-rays, electrocardiography, and a pulmonary function test were normal; however, the hypereosinophilia was aggravated (eosinophils, 3,934/µL). Oral deflazacort was administered. A cystoscopic biopsy showed chronic inflammation with eosinophilic infiltration. The patient’s respiratory, gastrointestinal, and urinary symptoms improved after 6 days of steroids, and he was discharged. The eosinophil count decreased dramatically (182/µL). The hypereosinophilia waxed and waned for 7 months, and the oral steroids were tapered and stopped. This case describes a patient diagnosed with eosinophilic cystitis and HES

A Case of Renal Cortical Necrosis in a 15-year-old Boy with Acute Kidney Injury

Renal cortical necrosis (RCN) is patchy or diffuse ischemic destruction of the renal cortex caused by significantly reduced renal arterial perfusion. It is a rare cause of acute kidney injury (AKI) and is associated with high mortality. Here, we review the case of RCN in a 15-year-old boy who developed AKI. A 15-year-old boy was referred to our hospital from a local hospital due to a sharp decrease in his renal function. He presented with acute flank pain, nausea with vomiting, and oliguria for the past two days. He had taken a single dose of antihistamine for nasal congestion. At our hospital, his peak blood pressure was 148/83 mmHg and he had a high body mass index of 32.9 kg/m2. The laboratory data showed a blood urea nitrogen (BUN) of 28.4 mg/dL, a creatinine of 4.26 mg/dL, and a glomerular filtration rate estimated from the serum cystatin C of 20.2 mL/min/1.73m2. Proteinuria (spot urine protein to creatinine ratio 1.66) with pyuria was observed. Kidney sonography showed parenchymal swelling and increased renal echogenicity. Due to rapidly progressing nephritis, steroid pulse therapy (750 mg/IV) was done on the second day of his admission and the patient showed complete recovery with normal renal function. However, the kidney biopsy findings revealed renal cortical hemorrhagic necrosis. Multifocal, relatively well-circumscribed, hemorrhagic necrotic areas (about 25%) were detected in the tubulointerstitium. Although RCN is an unusual cause of AKI, especially in children, pediatricians should consider the possibility of RCN when evaluating patients with rapidly decreasing renal function

Association of Neutrophil Gelatinase associated Lipocalin and Leukocyte Differential Count in Children with Febrile Urinary Tract Infections

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-tolymphocyte 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

Plasma Neutrophil Gelatinase-associated Lipocalin and Leukocyte Differential Count in Children with Febrile Urinary Tract Infection

Purpose We aimed to study the association of plasma neutrophil gelatinase-associated lipocalin (pNGAL) and leukocyte differential count in children with febrile urinary tract infection (UTI). Methods Medical records of 154 children aged 1 month to 13 years with febrile UTI who were hospitalized were retrospectively reviewed. Associations between pNGAL levels and blood leukocyte differential count at admission and after 48 hours of treatment were investigated in children with or without acute pyelonephritis (APN). Results The APN group (n=82) showed higher pNGAL levels, neutrophil count, monocyte count, and neutrophil-to-lymphocyte ratio (NLR), compared to the non-APN group (n=72) (all P<0.05). After adjustment for age and sex, pNGAL showed positive correlations with neutrophil count and NLR in both groups (all P<0.05). Additionally, it was correlated with the monocyte-to-lymphocyte ratio (MLR) only in the APN group (P<0.05). Before and after treatment, pNGAL was positively correlated with neutrophil count, NLR, and MLR in patients with APN while it was related with neutrophil count and NLR in those without APN (all P<0.05). Areas under the receiver operating curve of pNGAL, neutrophil count, NLR, and MLR for predicting APN were 0.804, 0.760, 0.730, and 0.636, respectively (all P<0.05). Only pNGAL was independently associated with the presence of APN in a multivariable logistic regression analysis (P<0.05). Conclusion In children with febrile UTIs, pNGAL might be associated with leukocyte differential count and the presence of APN