Renal biopsy criterion in idiopathic nephrotic syndrome with microscopic hematuria at onset

IgA nephropathy in a boy with frequently relapsing nephrotic syndrome

A Japanese boy developed nephrotic syndrome (NS) and had microscopic hematuria at 8 years old. Renal biopsy was performed. Light microscopy study revealed mesangial proliferation and all immunofluorescent stains (including IgA) were negative, so he was diagnosed with non-IgA diffuse mesangial proliferation (DMP). Complete remission was achieved at 13 days after the initiation of oral prednisolone, and hematuria also disappeared 3 days later, but the patient developed frequently relapsing nephrotic syndrome. Cyclosporine A (CyA) was introduced at 10 years old, and there were no relapses between then and when it was discontinued at 12 years old. A second renal biopsy revealed minimal change without CyA nephrotoxicity. However, there was repeated relapse of NS after discontinuation, so CyA was reintroduced 8 months later, and NS remained in remission thereafter. Microscopic hematuria appeared at 13 years old, however, with gross hematuria appearing at the time of infection. A third renal biopsy revealed mesangial proliferation with IgA-dominant deposition, so the patient was diagnosed with IgA nephropathy. Currently (14 years old), CyA treatment has been discontinued and the patient is undergoing lisinopril therapy for IgA nephropathy, but there are still relapses of NS. To the best of our knowledge, there have been no previous reports of a patient with non-IgA DMP at the onset of NS who had later development of IgA nephropathy. The patient showed non-IgA DMP at the onset, suggesting that NS with non-IgA DMP and IgA nephropathy has some common pathophysiology. Treatment for NS, such as PSL and/or CyA treatment, may suppress the clinical manifestation of late IgA nephropathy.

Is kidney biopsy necessary in children with idiopathic nephrotic syndrome?

AIM

To investigate the need, in the Northern European setting, to perform kidney biopsy in children with steroid-sensitive nephrotic syndrome.

METHODS

In this retrospective study 124 individuals aged 1-18 years with idiopathic nephrotic syndrome, followed in the paediatric hospitals in southern Sweden from 1999 to 2018, were included.

RESULTS

There was a median follow-up time of 6.5 (0.2-16.8) years. The majority (92%) of children were steroid-sensitive and of them, 60.5% were frequently relapsing or steroid-dependent. Microscopic haematuria was found at onset in 81.1% and hypertension in 8.7%. At least one kidney biopsy was performed in 93 (75%). The most common indication was a steroid-dependent or relapsing course (58.4%). One of 79 steroid-sensitive children had another histological diagnosis than minimal change nephropathy 1.3%, 95% confidence interval (0.002, 0.068). Bleeding occurred after eight biopsies (6.6%). Twenty individuals (30.7%) were transferred to adult units, 18 still on immunosuppression.

CONCLUSION

We have in our cohort of unselected children with idiopathic nephrotic syndrome confirmed that a kidney biopsy rarely gives important medical information in steroid-sensitive children without any other complicating factor and that the liberal policy of kidney biopsy in the Nordic countries safely can be changed.

IPNA clinical practice recommendations for the diagnosis and management of children with steroid-sensitive nephrotic syndrome

Idiopathic nephrotic syndrome is the most frequent pediatric glomerular disease, affecting from 1.15 to 16.9 per 100,000 children per year globally. It is characterized by massive proteinuria, hypoalbuminemia, and/or concomitant edema. Approximately 85-90% of patients attain complete remission of proteinuria within 4-6 weeks of treatment with glucocorticoids, and therefore, have steroid-sensitive nephrotic syndrome (SSNS). Among those patients who are steroid sensitive, 70-80% will have at least one relapse during follow-up, and up to 50% of these patients will experience frequent relapses or become dependent on glucocorticoids to maintain remission. The dose and duration of steroid treatment to prolong time between relapses remains a subject of much debate, and patients continue to experience a high prevalence of steroid-related morbidity. Various steroid-sparing immunosuppressive drugs have been used in clinical practice; however, there is marked practice variation in the selection of these drugs and timing of their introduction during the course of the disease. Therefore, international evidence-based clinical practice recommendations (CPRs) are needed to guide clinical practice and reduce practice variation. The International Pediatric Nephrology Association (IPNA) convened a team of experts including pediatric nephrologists, an adult nephrologist, and a patient representative to develop comprehensive CPRs on the diagnosis and management of SSNS in children. After performing a systematic literature review on 12 clinically relevant PICO (Patient or Population covered, Intervention, Comparator, Outcome) questions, recommendations were formulated and formally graded at several virtual consensus meetings. New definitions for treatment outcomes to help guide change of therapy and recommendations for important research questions are given.

Idiopathic nephrotic syndrome in children

The incidence of idiopathic nephrotic syndrome (NS) is 1·15-16·9 per 100 000 children, varying by ethnicity and region. The cause remains unknown but the pathogenesis of idiopathic NS is thought to involve immune dysregulation, systemic circulating factors, or inherited structural abnormalities of the podocyte. Genetic risk is more commonly described among children with steroid-resistant disease. The mainstay of therapy is prednisone for the vast majority of patients who are steroid responsive; however, the disease can run a frequently relapsing course, necessitating the need for alternative immunosuppressive agents. Infection and venous thromboembolism are the main complications of NS with also increased risk of acute kidney injury. Prognosis in terms of long-term kidney outcome overall is excellent for steroid-responsive disease, and steroid resistance is an important determinant of future risk of chronic or end-stage kidney disease.

The Role of Glucocorticoid Receptors in Podocytes and Nephrotic Syndrome

Glucocorticoid receptor (GC), a founding member of the nuclear hormone receptor superfamily, is a glucocorticoid-activated transcription factor that regulates gene expression and controls the development and homeostasis of human podocytes. Synthetic glucocorticoids are the standard treatment regimens for proteinuria (protein in the urine) and nephrotic syndrome (NS) caused by kidney diseases. These include minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN) and immunoglobulin A nephropathy (IgAN) or subsequent complications due to diabetes mellitus or HIV infection. However, unwanted side effects and steroid-resistance remain major issues for their long-term use. Furthermore, the mechanism by which glucocorticoids elicit their renoprotective activity in podocyte and glomeruli is poorly understood. Podocytes are highly differentiated epithelial cells that contribute to the integrity of kidney glomerular filtration barrier. Injury or loss of podocytes leads to proteinuria and nephrotic syndrome. Recent studies in multiple experimental models have begun to explore the mechanism of GC action in podocytes. This review will discuss progress in our understanding of the role of glucocorticoid receptor and glucocorticoids in podocyte physiology and their renoprotective activity in nephrotic syndrome.

IgA Nephropathy in Children: A Multicenter Study in Poland

IgA nephropathy (IgAN) is the most common form of glomerulonephritis in pediatric population. The clinical presentation of the disease in children ranges from microscopic hematuria to end-stage kidney disease. The aim of the study was to retrospectively assess clinical and kidney biopsy features in children with IgAN. We assessed a cohort of 140 children, 88 boys, 52 girls with the diagnosis of IgAN in the period of 2000-2015, entered into the national Polish pediatric IgAN registry. The assessment included the following: proteinuria, hematuria, glomerular filtration rate (GFR), arterial blood pressure, and the renal pathological changes according to the Oxford classification and crescents formation, as modifiable and unmodifiable risk factors. The incidence of IgAN in Poland was set at 9.3 new cases per year. The mean age at onset of IgAN was 11.9 ± 4.3 years, and the most common presentation of the disease was the nephritic syndrome, recognized in 52 % of patients. Kidney biopsy was performed, on average, 1.3 ± 2.0 years after onset of disease. Based on the ROC analysis, a cut-off age at onset of disease for GFR <90 mL/min/1.73 m² (risk factor of progression) was calculated as 13.9 years. Unmodifiable lesions: segmental sclerosis, tubular atrophy/interstitial fibrosis (S1, T1-2) in the Oxford classification and crescents in kidney biopsy were significantly more common in Gr 1 (>13.9 years) compared with Gr 2 (<13.9 years), despite a significantly shorter time to kidney biopsy in the former. We conclude that IgAN in children may be an insidious disease. A regular urine analysis, especially after respiratory tract infections, seems the best way for an early detection of the disease.

Nephrotic syndrome: what's new, what's hot?

While the incidence of nephrotic syndrome (NS) is decreasing in Korea, the morbidity of difficult-to-treat NS is significant. Efforts to minimize treatment toxicity showed that prolonged treatment after an initial treatment for 2-3 months with glucocorticosteroids was not effective in reducing frequent relapses. For steroid-dependent NS, rituximab, a monoclonal antibody against the CD20 antigen on B cells, was proven to be as effective, and short-term daily low-dose steroids during upper respiratory infections reduced relapses. Steroid resistance or congenital NS are indications for genetic study and renal biopsy, since the list of genes involved in NS is lengthening.