IgA nephropathy (IgAN) and Henoch-Schönlein purpura nephritis (HSPN) are most frequently found chronic glomerulonephritis (CGN) in childhood. Recently, it has been reported that the pathogenesis of IgAN and HSPN may be associated with the circulation of defective forms of IgA1 or the presence of in situ immune complexes, and the onset and progression of inflammation are thought to be associated with complement components, activated macrophages and mesangial cells. To prevent progression to chronic renal injury, it is important to control these abnormal immunoresponse. For children with severe CGN, the long-term prognosis was improved by multi-drug combination therapy including steroid and immunosuppressive drugs, plasmapheresis and LDL-apheresis. On the other hand, hemolytic uremic syndrome (HUS) is defined as a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure and the cause is Shiga toxin-producing Escherichia coli infection in most infant cases. We produced an adequate HUS model for the study of the recovery process from acute renal injury, and studied its mechanism, renal regeneration factor, and the treatment of HUS by using this model.

“Clinical classification (syndromes) of glomerular diseases” by WHO is useful in renal disease management. It is a classification consisting of five categories: 1) acute nephritic syndrome, 2) rapidly progressive nephritic syndrome, 3) recurrent or persistent hematuria, 4) chronic nephritic syndrome, and 5) nephrotic syndrome. One of the most important things in using this classification is that each category is a disease condition, not a disease name. That is, there is not a disease called “acute nephritic syndrome” and it is essential to recognize it as a disease condition. Notably, “acute nephritic syndrome” should not be confused with “acute nephritis”. Since “glomerulonephritis” is often abbreviated as “nephritis”, “acute nephritis” is frequently used as “acute glomerulonephritis”. Therefore, it often happens that “acute nephritic syndrome” is confused with “acute nephritis”. We should know that “acute nephritic syndrome” is a disease condition defined as “a syndrome characterized by abrupt onset of macroscopic hematuria, proteinuria, hypertension, decreased glomerular filtration, and retention of sodium and water”, and that “acute nephritis” is an abbreviation of a disease name “acute glomerulonephritis”.

Recently, robot-assisted surgery has gained popularity in urological field and especially, robot-assisted radical prostatectomy for localized prostate cancer and robot-assisted partial nephrectomy for small kidney cancer has been established as gold standard in Japan. The daVinci surgical system (Intuitive Surgical, Sunnyvale, CA, USA) provides the advantages of simplification and precision of exposure and suturing because of allowing movements of the robotic arm in real time with increased degree of freedom and magnified 3-dimentional view. These main advantages of robot-assisted surgery are expected to be applied to pediatric urology patients. In this review, we discuss the recent advances in robot-assisted reconstruction surgery in pediatric urology, such as pyeloplasty for ureteropelvic junction obstruction and ureteral reimplantation for vesicoureteral reflux, and provide a critical summary of current knowledge on its outcome. In conclusion, urological reconstruction surgery for children could be replaced with robot-assisted surgery, which may be established as minimally invasive surgery in the future.

The major cause of childhood chronic kidney disease (CKD) is congenital abnormalities of the kidney and urinary tract (CAKUT). For the management of the hypertension, we have to be careful about the difference by age, the variability of blood pressure, white coat hypertension and the possibility of nonadherence of patients. It is important to understand characteristics and major side effects of drugs. If infants of CKD present with growth failure due to poor nutrition, we had better start tube feeding. Low-protein diet is not recommended, although for some patients it might be useful. In patients with hypertension, salt restriction is effective. However, it is not recommended for some patients with CAKUT or nephronophthisis. Obesity is a risk factor for progression of CKD. Gene analysis is useful for the avoidance of strong immunosuppressive treatment, early detection of extra-renal diseases, predictions of post-transplant recurrences, and diagnosis of other patients in the family. In the management of pediatric CKD, we should provide individualised care to each patient depending on the condition.

It is thought that the long term observation was necessary for the postoperative patients with vesicoureteral reflux (VUR), since long term prognosis is vague and some of them with preserved renal function in the initial stage even might develop progressive renal dysfunction. We performed a retrospective study to clarify this problem. We analyzed changes in the %Cr (basal serum creatinine value/measured serum creatinine value ×100%) of 199 patients observed postoperatively more than 5 years between 2000 and 2005 in our hospital. Of 199 patients, 135 (68%) were male, 159 (80%) had bilateral VUR. Median age was 3 years at the surgery (range 0.4–16.5 years) and median observational duration was 10 years (range 5.0–15.2 years). VUR disappeared in 97.5%. Fifty one out of 199 patients had eGFR less than 90 ml/min/1.73 m² at last-observation, and their mean %Cr was 77% preoperatively, 85% at 2 years after the operation, and 75% at last-observation. %Cr was significantly lower at last than 2 year-postoperative observation in them. This report shows that kidney function declined after the operation in many patients even if renal function is maintained for a short period of time.

We routinely perform renal ultrasonography screening in all infants who undergo a health checkup at 1 month of age. In the past 11 years, 106 cases of dilation of the central echo complex (CEC) have been reported. We analyzed the correlation between the anteroposterior diameter (APD) of the renal pelvis at the screening and consequences of patients. Considering that the patients whose renal pelvis dilatation had not resolved spontaneously had significantly longer APD (p=0.0457), patients with long APD should be followed up carefully. We also investigated the cutoff APD of the renal pelvis, which predicts cases requiring a detailed and more efficient examination. Although the cutoff APD may be revised adequately from 7.0–8.1 mm, missing cases that should be diagnosed as obstructive urinary tract diseases is a concern. Further study is needed to decide whether the cutoff value should be revised. In the patients whose CEC dilation resolved spontaneously, no correlation was found between the APD at screening and that during spontaneous regression. It may be difficult to predict the time of regression by evaluating the APD of the renal pelvis at screening.

Renal ultrasound screening was performed on 1018 apparently healthy 4-month-old infants in Sammu City to detect congenital abnormalities of the kidney and urinary tract (CAKUT). Ultrasound findings included hydronephrosis greater than grade 3 by the Society for Fetal Urology classification, and grade 2 with apparent or fluctuating renal calyceal dilatation, a renal length less than 42 mm, and a renal length discrepancy greater than 8 mm. Twenty-three infants (2.3%) had positive ultrasound findings and were referred to hospital. Of these, 11 (1.1%) had hydronephrosis, 5 with grade 3 and 6 with grade 2, respectively. Seven infants (0.69%) had a renal length less than 42 mm. Finally, 7 infants with CAKUT (0.69%) were identified. Bilateral grade III and IV vesicoureteral reflux (VUR) with small kidney requiring surgery, pelviureteric junction obstruction, and megaureter with ureterocele were detected in 3 infants with grade 3 hydronephrosis and renal length discrepancy. Bilateral grade IV VUR was detected in 1 infant with grade 2 hydronephrosis with fluctuating pyelocalyceal dilatation. Ultrasound was effective for the early detection of CAKUT. Clear criteria for positive ultrasound findings without excessive screening of hydronephrosis would enable renal ultrasound screening by general pediatricians and medical technologists, reduce first positive screening rate, and improve medical cost-benefits.

Relapses of nephrotic syndrome (NS) are commonly treated with a course of prednisolone (2 mg/kg/day or 60 mg/m²/day), which is recommended in several guidelines. Though we often experience treating relapses of NS with PSL lower than recommended dosage, the effects and prognosis of treating lower dosage PSL are unknown. We retrospectively studied 49 steroid-sensitive NS children who were treated first relapse of NS in our center between 2005 and 2016. The median dose of PSL used to relapse was 1.93 mg/kg/day and 27 (55.1%) patients were treated less than 2 mg/kg/day. All patients responded within 15 days. There was no correlation between dose of PSL and days until remission (r=0.14). Twenty-three (46.9%) patients were frequently-relapsing nephrotic syndrome (FRNS), who had more than two times relapses during 6 months after first NS remission. Among FRNS patients, age at the onset of NS, PSL dosage at first relapse, and days until remission were no significant difference compared to these parameters in non-FRNS patients. Our study found that lower dose of PSL in treating a first relapse of NS was not influence the prognosis.

We retrospectively analyzed the clinical course of 93 consecutive children with nephrotic syndrome (NS) who had been followed-up at Saitama Children’s Medical Center for at least one year since initial presentation. Of the 93, eight were asymptomatic without edema (asymptomatic patients) and were identified by chance proteinuria in urinary screening program. A total of 80% (75/93) were classified as having steroid-sensitive NS (seven in asymptomatic patients and 68 in symptomatic patients). The mean number of days to complete remission after initial steroid therapy in asymptomatic patients was significantly shorter than that in symptomatic patients (6.0 vs 10.0 days, p<0.01). Furthermore, none of the seven asymptomatic patients with steroid-sensitive NS developed FR/SDNS during follow-up period. Although all of 17 symptomatic patients with steroid-resistant NS achieved complete remission after the initiation of immunosuppressive agents, WT-1 mutation was detected in one asymptomatic patient with steroid and cyclosporine-resistant NS. We conclude that genetic testing should be done for asymptomatic patients with steroid-resistant NS before the initiation of immunosuppressive agents.

In recent years, augmentation enterocystoplasty is actively performed for pediatric cases of neurogenic bladder that are resistant to conservative treatments such as anticholinergic drugs. Our patient was a 24-year-old woman. At the age of 7 years, she underwent augmentation cystoplasty via the sigmoid colon. She subsequently underwent continuous clean intermittent catheterization and intestinal lavage while being followed up at the pediatric nephrology department. At the age of 24, she became pregnant; however, she was hospitalized at 26 weeks of gestation because she developed post-renal failure with bilateral hydronephrosis. She underwent bilateral nephrostomy construction at the urology department. As a result, hydronephrosis and her renal function improved, and her infant was delivered at term. Although asymptomatic bacteriuria was noted halfway through the pregnancy, her urinary test results improved following administrations of antibacterial agents, and no pyelonephritis developed. Because the number of pregnancy cases following augmentation cystoplasty is predicted to increase going forward, pediatrician need to promote transition to adult services.

A 12-years-old girl visited our hospital complaining of fever, headache and nausea. She had a past history of taking acetaminophen. Present history revealed that fever and symptoms persisted for 1 month, and laboratory data showed elevation of CRP, creatinine, total IgE and IgG levels. Autoantibodies were negative. Urinalysis indicated mild proteinuria and markedly increase in β₂-microglobulin and NAG levels. Abdominal diffusion-weighted magnetic resonance imagings showed bilateral kidney enlargements with pathy high intensity lesions, which were similar to the findings of malignant tumor or IgG4-related kidney diseases. Bone marrow puncture test revealed normal. The administration of minocycline normalized fever and CRP levels except for the increase in serum creatinine levels. These findings led us to perform renal biopsy. Then, we found interstitial infiltrates composed of lymphocytes, plasma cells, neutrophils, eosinophils, and also severe tubulitis in the absence of storiform fibrosis. Staining of IgG subclasses showed plasma cells which were dominantly positive for IgG1 and also weakly positive for IgG4. A drug lymphocyte stimulation test for acetaminophen showed a positive result, which led us to diagnose drug-induced tubulointerstitial nephritis. On the basis of these clinical findings, IgG subclass staining in renal biopsy might be useful to distinguish drug-induced tubulointerstitial nephritis from IgG4-related kidney disease.

Nephrologists tend initially to suspect primary kidney diseases when they encounter patients with a chronic kidney disease accompanied by other organ dysfunctions. However, it is important to consider the possibility of thyroid disease as well. We report a rare case of primary hypothyroidism with the main symptom of decreased renal function accompanied by anemia and short stature. An 11-year-old girl with anemia, decreased renal function, and mild liver dysfunction had been followed by another department for one year. She was referred to us for progressive, decreased renal function and probable, secondary renal anemia. The patient presented short stature, and primary hypothyroidism was diagnosed. She was treated with thyroid hormone replacement therapy. Her renal function normalized within three months. Her anemic state, liver function, and growth rate also improved in six months. When a patient with a chronic kidney disease also shows other organ dysfunctions, hypothyroidism should be kept in mind as one of the main differential diagnoses, because decreased renal function due to hypothyroidism is reversible.