Pediatric steroid-resistant nephrotic syndrome

Overexpression of P-glycoprotein and MRP-1 are pharmacogenomic biomarkers to determine steroid resistant phenotype in childhood idiopathic nephrotic syndrome

Steroid remains the keystone therapy for Idiopathic Nephrotic Syndrome (NS). Besides genetic factors and histological changes, pharmacogenomic factors also affect the steroid response. The upregulation of P-glycoprotein (P-gp) and Multidrug resistance-associated protein 1 (MRP-1) modulate the pharmacokinetics of steroids and may contribute to steroid resistance. Flow-cytometric analysis of P-gp, MRP-1 expression and functional activity on peripheral blood mononuclear cells (PBMCs) was carried out in steroid-sensitive nephrotic syndrome (SSNS) (n = 171, male 103, mean age = 8.54 ± 4.3); and steroid-resistant nephrotic syndrome (SRNS) (n = 83, male 43, mean age = 7.43 ± 4.6) patients. The genotypings of MDR-1 gene were carried out using PCR-RFLP. We observed that the percentage expression of P-gp (10.01 ± 2.09 and 3.79 ± 1.13, p < 0.001); and MRP-1 (15.91 ± 3.99 and 7.40 ± 2.33, p < 0.001) on lymphocyte gated population were significantly higher in SRNS than that of SSNS. The functional activity of P-gp and MRP-1 was also significantly escalated in SRNS as compared to SSNS (68.10 ± 13.35 and 28.93 ± 7.57, p < 0.001); (72.13 ± 8.34 and 31.56 ± 8.65, p < 0.001) respectively. AUC-ROC curve analysis revealed that P-gp and MRP-1 expression with a cut-off value of 7.13% and 9.62% predicted SRNS with the sensitivity of 90% and 80.7%; and specificity 90% and 80%, respectively. Moreover, MDR-1 homozygous mutant TT+AA for G2677T/A (rs2032582) was significantly associated with SRNS (p = 0.025, OR = 2.86 CI = 1.14-7.14). The expression of P-gp (9.68 ± 4.99 v/s 5.88 ± 3.38, p = 0.002) was significantly higher in the patients of homozygous mutant alleles compared to wildtype GG. The increased expression and functionality of P-gp and MRP-1 contribute to steroid resistance, and MDR-1 homozygous mutant G2677T/A promotes steroid resistance by inducing P-gp expression in NS.

ABCB1 polymorphisms and steroid treatment in children with idiopathic nephrotic syndrome

BACKGROUND

The most common cause of nephrotic syndrome (NS) is idiopathic nephrotic syndrome (INS), also called nephrosis. Although most patients respond to steroid therapy, there is unequal response to treatment suggesting the involvement of genetic factors. The current study was conducted to evaluate the influence of two single nucleotide polymorphisms (SNPs) in ABCB1 (C3435T and C1236T) on the steroid treatment response in INS children.

MATERIALS AND METHODS

Genotyping of ABCB1 C3435T and C1236T polymorphisms by real time PCR were conducted on 120 INS children, 80 steroid sensitive (SS) and 40 steroid resistant (SR).

RESULTS

A significant difference in the distribution of ABCB1 C3435T and C1236T genotypes was observed between SS and SR patients. C1236T polymorphism was associated with steroid resistance in INS children (odds ratio: 2.27, 95 % confidence interval: 1.2-4.4; P = 0.012). The frequency of the T allele was significantly higher in SR than in SS patients (81.2 vs. 65.6%, respectively). The odds ratio for the C3435T polymorphism in response to steroid treatment was smaller than that of the polymorphism C1236T, and did not reach statistical significance (odds ratio: 1.1, 95 % confidence interval: 0.6-1.9; P = 0.77).

CONCLUSION

Our results suggested that C1236T polymorphism in ABCB1 gene was associated with steroid resistance. A higher proportion of SR children had C1236T TT genotype and T allele, these patients may require other therapeutic strategies.

Steroid-resistant nephrotic syndrome with mutations in NPHS2 (podocin): report from a three-generation family

Genetic causes of steroid-resistant nephrotic syndrome are being increasingly recognized. Mutations in NPHS2, which encodes the glomerular protein podocin, account for up to 17% of sporadic and 40% of familial cases, where they display an autosomal-recessive pattern of inheritance. This report describes a non-consanguineous family with three generations of individuals who are either compound heterozygotes for mutations in NPHS2 or who have inherited a mutation and a non-neutral polymorphism (R229Q). As well as providing an aetiological explanation, identifying pathogenic mutations and considering genotype-phenotype correlations can provide prognostic information and lead to changes in genetic counselling and management.

254C>G: a TRPC6 promoter variation associated with enhanced transcription and steroid-resistant nephrotic syndrome in Chinese children

BACKGROUND

Mutations in canonical transient receptor potential channel 6 (TRPC6) have been identified as responsible for the development of focal segmental glomerulosclerosis, a proteinuric disease with steroid resistance and poor prognosis. This study explores the prevalence of TRPC6 variants in Chinese children with idiopathic nephrotic syndrome (INS), the genotype/phenotype correlation of TRPC6 variants, the therapeutic response, and the underlying molecular mechanism.

METHODS

Fifty-one children with sporadic INS were enrolled: 23 steroid-sensitive cases and 28 steroid-resistant cases Polymerase chain reaction was used to amplify 13 exons and the promoter sequences of TRPC6 before sequencing. The expression of TRPC6 in renal tissues was illustrated by immunohistochemistry staining. The transcriptional activity of variants in TRPC6 promoter was measured by the luciferase assay.

RESULTS

Three variants (-254C>G, rs3824934; +43C/T, rs3802829; and 240 G>A, rs17096918) were identified. The allele frequency of the -254C>G single-nucleotide polymorphism (SNP) in the steroid-resistant nephrotic syndrome (SRNS) patients (40.5%) was higher than that in the steroid-sensitive nephrotic syndrome subjects (27.1%; P = 0.046). The -254C>G SNP enhanced transcription from TRPC6 promoter in vitro and was associated with increased TRPC6 expression in renal tissues of SRNS patients.

CONCLUSION

-254C>G, a SNP underlying enhanced TRPC6 transcription and expression, may be correlated with the development of steroid resistance in Chinese children with INS.

Treatment outcome of late steroid-resistant nephrotic syndrome: a study by the Midwest Pediatric Nephrology Consortium

BACKGROUND

Idiopathic nephrotic syndrome (NS) in children is classified as steroid sensitive or steroid resistant. Steroid sensitivity typically portends a low risk of permanent renal failure. However, some initially steroid-sensitive patients later develop steroid resistance. These patients with late steroid resistance (LSR) are often treated with immunosuppressant medications, but the effect of these additional drugs on the long-term prognosis of LSR is still unknown.

METHODS

A retrospective chart review was performed on patients diagnosed with idiopathic NS and subsequent LSR during the 8-year study period from 2002 up to and including 2009, with a minimum of 2 years of follow-up. Primary outcome measures were proteinuria and renal function.

RESULTS

A total of 29 patients were classified as having LSRNS. The majority of patients received treatment with calcineurin inhibitors and/or mycophenolate mofetil. Seven patients received three or more non-steroid immunosuppressant medications. Sustained complete or partial remission was achieved in 69 % of patients. Three developed end-stage renal disease, and all others maintained normal renal function. There were 13 episodes of serious adverse events, none of which were fatal or irreversible.

CONCLUSION

Most patients with LSRNS responded to immunosuppressive therapy by reduction or resolution of proteinuria and preservation of renal function. The results suggest that immunosuppressive treatment is a viable option in NS patients who develop LSR.

Genetic polymorphisms influence the steroid treatment of children with idiopathic nephrotic syndrome

BACKGROUND

Idiopathic nephrotic syndrome (INS) is the most frequent type of nephrotic syndrome that occurs in children. Its response to treatment with steroids varies. The aim of this study was to analyze the correlation between steroid metabolism-related genes and the response to steroid treatment.

METHODS

The patient cohort comprised 74 children with INS, of whom were 58 steroid-sensitive (SS) cases and 16 steroid-resistant (SR) cases. The genetic polymorphisms analyzed were those of the CYP3A5 gene (A6986G) and ABCB1 gene (C1236T, G2677T/A, and C3435T), and the polymorphisms between SS and SR children were compared.

RESULTS

C1236T in ABCB1 was associated with steroid resistance in INS children [odds ratio (OR) 2.65, 95 % confidence interval (CI) 1.01-6.94; p = 0.042] The frequency of the T allele was significantly higher in SR subjects than in SS subjects (0.81 vs. 0.62, respectively). A6986G in CYP3A5 showed a trend of association, but this association did not reach statistical significance (OR 2.63, 95 % CI 0.94-7.37; p = 0.059). No significant correlation was found between treatment response and G2677T/A or C3435T in ABCB1.

CONCLUSIONS

Our results indicate that among our pediatric patients with INS the C1236T polymorphism in the ABCB1 gene was associated with steroid resistance, while the A6986G polymorphism in the CYP3A5 gene showed a trend of association, but did not reach statistical significance, requiring further analysis.

Distinct metalloproteinase excretion patterns in focal segmental glomerulosclerosis

Metalloproteinase-2 (MMP-2) and metalloproteinase-9 (MMP-9) degrade type IV collagen, and represent important tissue remodeling enzymes in several kidney disorders. In this study, we measured urinary levels of MMP-2, MMP-9, and the tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) in patients with steroid-sensitive nephrotic syndrome (SSNS, n = 18, median age 5) and focal segmental glomerulosclerosis (FSGS, n = 16, median age 15). We found that urinary concentrations of MMP-2, MMP-9, TIMP-1, and TIMP-2 were significantly elevated in FSGS patients as compared to SSNS in both relapse and remission (p < 0.002). Furthermore, urinary levels of these enzymes are increased early on in the FSGS disease process (chronic kidney disease stages 1 and 2). The findings from this pilot study suggest that MMPs and TIMPs have the potential to represent candidate, early non-invasive biomarkers for diagnosis and/or response to therapy. In addition, they may represent therapeutic targets for preventing chronic kidney disease progression in FSGS.

Treatment of steroid and cyclosporine-resistant idiopathic nephrotic syndrome in children

Steroid-resistant nephrotic syndrome (SRNS) in children carries a significant risk of progression to end-stage renal failure (ESRF). We report a two-step protocol adapted in children with SRNS. Thirty-seven SRNS were treated with cyclosporine A (CyA) in association with prednisolone (alternate day) for 6 months (first-step treatment). Twelve patients (32.4%) went into complete remission, and 2 (5.4%) got partial remission. The other 23 cases who were steroid and CyA resistant entered a second-step treatment with withdrawing steroids, with CyA (5 mg/kg/day) in association with mycophenolate mofetil (MMF) 30 mg/kg/day for 6 months. Complete remission was observed in 11 cases (47.82%) and partial remission in 2 cases (8.7%). After two steps of treatment, 27/37 children went into total remission. In steroid and CyA-resistant INS, the association of MMF with CyA was able to induce remission in about half cases without relevant side effects.

Role of free radicals and antioxidant status in childhood nephrotic syndrome

Nephrotic syndrome (NS) is characterized by heavy proteinuria and hypoalbuminuria. Reactive oxygen species (ROS) seem to play an important role in the etiopathogenesis of proteinuria in NS. This study aims to evaluate the potential role of reactive oxygen species in pathogenesis of NS by estimating the levels of oxidants and antioxidants in children with NS. Thirty patients of NS and thirty age, sex-matched healthy subjects, were selected for the study. As compared to healthy controls, the levels of serum lipid peroxide were significantly elevated while levels of nitric oxide, erythrocyte-superoxide dismutase activity, levels of vitamin C, albumin and total antioxidant capacity were significantly reduced in nephrotic patients. The levels of uric acid and bilirubin were significantly increased in children with NS as compared to controls. There was no significant difference in vitamin E level between patients and controls. It can be concluded that increased ROS generation and decreased antioxidant defense may be related to the pathogenesis of proteinuria in NS.

Genetics of proteinuria: an overview of gene mutations associated with nonsyndromic proteinuric glomerulopathies

Heritable causes of proteinuria are rare and account for a relatively small proportion of all cases of proteinuria affecting children and adults. Yet, significant contributions to understanding the mechanistic basis for proteinuria have been made through genetic and molecular analyses of a small group of syndromic and nonsyndromic proteinuric disorders which are caused by mutations encoding structural components of the glomerular filtration barrier. Technological advances in genomic analyses and improved accessibility to mutational screening at clinically approved laboratories have facilitated diagnosis of proteinuria in the clinical setting. From a clinical standpoint, it may be argued that a genetic diagnosis mitigates exposure to potentially ineffective and harmful treatments in instances where a clear genotype-phenotype correlation exists between a specific gene mutation and treatment nonresponsiveness. However, cautious interpretation of risk may be necessitated in cases with phenotypic heterogeneity (eg, variability in clinical or histological presentation). This review summarizes gene mutations which are known to be associated with proteinuric glomerulopathies in children and adults.

Mycophenolate mofetil therapy for children with steroid-resistant nephrotic syndrome

Treating children with steroid-resistant nephrotic syndrome (SRNS) has been a clinical challenge for pediatricians. We recruited 24 children (18 boys and six girls) with steroid-resistant idiopathic nephrotic syndrome (SRINS) who were <2 years. All patients were administered prednisone 2 mg/kg per day prior to mycophenolate mofetil (MMF). By the end of the eighth week, MMF was initiated at 25-30 mg/kg daily for 6- 12 months. Prednisone dose was reduced stepwise. Biochemical assays were performed every 2 months. Complete remission was achieved in 15 patients, partial remission in six, and no response to MMF was noted in three. With MMF treatment, the levels of urinary protein and serum cholesterol decreased and that of serum albumin increased in a time-dependant manner. We demonstrated the MMF could reduce proteinuria in SRINS children <2 years. Our study suggests that MMF therapy might be an effective strategy for treating SRINS in children <2 years.

Role of reactive oxygen species in pathogenesis of nephrotic syndrome

Nephrotic syndrome is the common chronic disorder characterized by alteration of permeability of the glomerular capillary wall, resulting in its inability to restrict the urinary loss of proteins. Nephrotic syndrome is characterized by heavy proteinuria, hypoalbuminemia, hyperlipidemia associated with peripheral edema. The molecular basis of glomerular permselectivity remains largely unknown. In recent years it has been proposed that Nephrotic syndrome is a consequence of an imbalance between oxidant and antioxidant activity. The present study was aimed to test that the reactive oxygen species are the mediators of excessive protein permeability and other complications of Nephrotic syndrome. For this 30 adults with Nephrotic syndrome were studied. The control group comprised 30 healthy adults matched for age. Serum levels of lipid peroxides, nitric oxide (NO⊙), α- tocopherol, ascorbic acid, erythrocyte superoxide dismutase activity, serum albumin, uric acid, cholesterol and plasma total antioxidant capacity were measured. Student's 't' test was applied for statistical analysis. There was a significant increase in lipid peroxide (1.58 ± 0.42 in controls, 3.64 ±1.3 in patients) (P<0.001) levels in study group as compared with controls. α-tocopherol (12.95 ± 1.04 in controls, 9.93 ± 1.43 in patients) (P<0.001), erythrocyte SOD activity(1.88 ± 0.9 in controls 1.07 ± 0.5 in patients) (P=0.01), serum albumin(4.06 ± 0.50 in controls, 3.04 ± 0.11 in patients) (P<0.001), and plasma total antioxidant capacity (847.33 ± 126.83 in controls, 684.00±102.94 in patients) (P<0.001) were significantly decreased. There was non-significant increase in uric acid (P>0.05), a non-significant decrease in NO⊙ (38.48 ± 15.47 in controls 37.47 ± 14.27 in patients) (P>0.05) and ascorbic acid levels ascorbic acid,( 0.95 ± 0.31in controls 0.79 ± 0.30 in patients) (P>0.05) in study group as compared with controls. Imbalance between oxidants and antioxidants may contribute to pathogenesis of proteinuria and related complications in nephrotic syndrome.

Histopathological spectrum of childhood nephrotic syndrome in Pakistan

BACKGROUND

There is no information in international literature on the pattern of glomerulopathies in children with idiopathic nephrotic syndrome (INS) in Pakistan. We undertook this study to determine the pattern of glomerulopathies based on renal biopsies studied by light (LM), immunofluorescence (IF), and electron microscopy (EM).

METHODS

The study was conducted at Sindh Institute of Urology and Transplantation (SIUT), Karachi over 12 years (1996-2008). All children (<or=18 years) with INS in whom renal biopsy was performed were included. Renal biopsies were studied by LM, IF, and EM.

RESULTS

Of 538 children, 347 (64.4%) were male and 191 (35.5%) were female. Mean age was 9.79 +/- 4.59 years. The histopathological lesions comprised: minimal change disease (MCD) and its variants, 43.8%; focal segmental glomerulosclerosis (FSGS), 38.14%; membranous glomerulonephritis (GN) (MGN), 7.96%; mesangioproliferative GN (MesPGN), 4.81%; mesangiocapillary GN (MPGN), 3.14%; IgA nephropathy (IgAN), 1.11%; and other rare lesions.

CONCLUSION

MCD and its variants are the leading cause of overall INS in children, followed by FSGS, which is the predominant pathology in steroid-resistant and adolescent nephrotic syndrome (NS). Our data are in accordance with recent series from around the world with similar biopsy indications. The study defines the true pattern of glomerulopathies in childhood INS for the first time in Pakistan.

Experience with tacrolimus in children with steroid-resistant nephrotic syndrome

Children with steroid-resistant nephrotic syndrome (SRNS) are at risk of developing renal failure. We report here the results of a single-center retrospective observational study of the remission rate in pediatric patients with SNRS receiving tacrolimus. Serial renal biopsies from children on tacrolimus therapy were evaluated for tubulointerstitial fibrosis and transforming growth factor-beta immunostaining. Of the 16 children with SRNS, 15 went into complete remission after a median of 120 days of therapy. Nine children were able to stop steroids, while the others were on tapering doses. Forty-seven percent had relapses, most of which were steroid-responsive. Serial renal biopsies were obtained from seven children after a median treatment duration of 24 months; two of these children had increased tubulointerstitial fibrosis and four showed increased transforming growth factor-beta tissue staining. Children with worsening histological findings were younger. There was no significant association between tacrolimus exposure and biopsy changes, although the average trough level was higher in those children with worsening histological findings. In conclusion, tacrolimus may be a safe and effective alternative agent for inducing remission in children with SRNS. However, caution needs to be taken when prescribing this agent due to its narrow therapeutic index. Serial renal biopsies are necessary to check for subclinical nephrotoxicity, especially in younger children and those with higher trough levels.

Low prevalence of NPHS2 mutations in African American children with steroid-resistant nephrotic syndrome

In African American (AA) children, focal segmental glomerulosclerosis (FSGS) is the leading cause of nephrotic syndrome (NS). It has been shown that AA children suffer from FSGS and steroid-resistant nephrotic syndrome (SRNS) at a higher frequency and with a more severe renal outcome in comparison with Caucasian children. Previous mutation analysis of large cohorts revealed that a high percentage of childhood SRNS is monogenic and that mutations in podocin (NPHS2) and Wilms' tumor gene 1 (WT1) account for approximately 30% of SRNS in children. To test whether AA children with SRNS have a similar or a higher mutation rate, we performed mutation analysis of NPHS2 and WT1 in a cohort of AA children with SRNS. Direct sequencing was carried out for all exons of NPHS2 and for exons 8 and 9 of WT1. We ascertained 18 children of AA descent in whom renal biopsy findings showed FSGS in 13 patients (72%) and minimal-change disease in five patients (28%). In both NPHS2 and WT1, no disease-causing mutations were detected. Our data strongly suggest that in AA children with SRNS, the frequency of NPHS2 mutations is much lower than in large cohorts of pediatric SRNS patients in the general population. Knowledge of mutation rate of NPHS2 in different populations of SRNS patients facilitates the physician in planning a suitable genetic screening strategy for patients.

Clinical course and NPHS2 analysis in patients with late steroid-resistant nephrotic syndrome

A small fraction of patients with initial steroid-sensitive nephrotic syndrome (SSNS) develops late steroid resistance, i.e. a lack of remission after 4 weeks of relapse treatment despite previous response to steroids. The pathophysiological basis of late resistance and the long-term prognosis remain obscure. Fourteen out of 360 patients with SSNS who were seen in our department between 1954 and 2005 developed late resistance. Median age at onset of NS was 4 years and median duration of development of late resistance 4.6 months. Histology showed minimal-change (MC) nephropathy in six patients and focal segmental glomerulosclerosis (FSGS) in three patients on initial biopsy and four patients on repeat biopsies. Late resistance was treated with cyclophosphamide in five patients, cyclosporine A in three, and both drugs in one. Eight of these nine patients went into remission. All 14 patients maintained a stable kidney function during their period of observation. NPHS2 mutation analysis in eight patients revealed no pathogenic mutations, suggesting that late resistance is not typically associated with mutations in the NPHS2 gene. With respect to the clinical course, late resistance appears to resemble SSNS and is characterized by a favorable outcome.

Congenital nephrotic syndrome

When presented with an edematous infant who may be experiencing a severe infection, particularly an unusual one, it is important to include nephrotic syndrome in the differential diagnosis. Because drastic measures may be required to manage this illness, it is important to be able to recognize symptoms, compile needed diagnostic data, and commence appropriate treatment. A referred pediatric nephrologist can aid in diagnosis, direct management, and educate and support parents. The nephrologist is also instrumental in guiding ongoing care and preparing the infant for transplantation when it becomes necessary.

Angiotensin-converting enzyme gene polymorphism in children with idiopathic nephrotic syndrome

AIMS

To investigate the genetic polymorphism of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) in children with idiopathic nephrotic syndrome (INS), as well as its relationship with patient's clinical response to steroid therapy.

METHODS

Fifty-nine patients with INS were recruited and divided into 2 groups according to their clinical response to steroids: steroid-sensitive (SS) with 19 patients and non-SS with 40 patients, which was further divided into steroid-dependent (SD) and steroid-resistant (SR) groups with 35 and 5 patients, respectively. Seventy-nine children without previous renal diseases and negative proteinuria were enrolled as a control group. The genotypes for ACE I/D polymorphism, including DD, ID, and II, were analyzed.

RESULTS

The distribution of ACE DD, ID, and II genotypes in INS patients were 52.5, 10.2 and 37.3%, respectively; the corresponding numbers for the control group were 2.5, 25.3 and 72.2%, respectively. Patients with INS had a significantly higher percentage of DD genotype (p <0.001) than the control group. This higher incidence of the DD genotype was observed in both the SS and non-SS groups. A higher percentage of the DD genotype in the non-SS group and in the SD group as compared to the SS group (both p < 0.05) was also noted.

CONCLUSION

Our data shows that INS is associated with a higher incidence of the DD genotype, especially in non-SS patients. This finding suggests that the DD genotype may be a risk factor for INS and play a role in the clinical response to steroids.

The Potential Role of HMG-CoA Reductase Inhibitors in Pediatric Nephrotic Syndrome

OBJECTIVE

To evaluate the safety and efficacy of the hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) as a potential treatment option for the dyslipidemia associated with childhood nephrotic syndrome.

DATA SOURCES

Searches of MEDLINE (1966–April 2004), Cochrane Library, International Pharmaceutical Abstracts (1977–April 2004), and an extensive manual review of journals were performed using the key search terms nephrotic syndrome, familial hypercholesterolemia, dyslipidemia, and HMG-CoA reductase inhibitor.

STUDY SELECTION AND DATA EXTRACTION

Two prospective uncontrolled studies evaluating the safety and efficacy of statin therapy in pediatric nephrotic syndrome were included.

DATA SYNTHESIS

While an extensive amount of data is available in adult nephrotic syndrome in which statin therapy decreases total plasma cholesterol 22–39%, low-density lipoprotein cholesterol (LDL-C) 27–47%, and total plasma triglycerides 13–38%, only 2 small uncontrolled studies have been conducted evaluating the utility of these agents in pediatric nephrotic syndrome. These studies indicate that statins are capable of safely reducing total cholesterol up to 42%, LDL-C up to 46%, and triglyceride levels up to 44%.

CONCLUSIONS

Lowering cholesterol levels during childhood may reduce the risk for atherosclerotic changes and may thus be of benefit in certain patients with nephrotic syndrome. Statins have demonstrated short-term safety and efficacy in the pediatric nephrotic syndrome population. Implementing pharmacologic therapy with statins in children with nephrotic syndrome must be done with care until controlled studies are conducted in this population.

Intravenous pulse cyclophosphamide--is it effective in children with steroid-resistant nephrotic syndrome?

Treatment of steroid-resistant nephrotic syndrome (SRNS) remains a challenge to pediatric nephrologists. Recently, intravenous cyclophosphamide (IV-CPM) infusion was shown to be effective, safe, and economical for the treatment of SRNS, particularly minimal change disease (MCD), as it results in more sustained remissions, longer periods without proteinuria, and fewer significant side effects at a lower cumulative dose. A prospective study was conducted to evaluate IV-CPM infusions in the management of children with SRNS secondary to MCD or IgM nephropathy. Five patients with SRNS (4 IgM nephropathy and 1 MCD) received six monthly IV-CPM infusions at a dose of 500 mg/m(2). No patient achieved complete or sustained remission. Three patients attained partial remission, which was not sustained for more than 1 month post therapy. One patient progressed rapidly to end-stage renal disease during treatment. Side effects included vomiting in four patients and alopecia in one patient.

CONCLUSION

IV-CPM pulse therapy at a dose of 500 mg/m(2) is unsuccessful in obtaining complete or sustained remission in children with SRNS secondary to IGM nephropathy or MCD. Further randomized controlled studies with higher doses are required.

The management of idiopathic nephrotic syndrome in children

Childhood nephrotic syndrome is a rare condition with an incidence of 1-2 per 100000 children aged below 16 years. Untreated idiopathic nephrotic syndrome (INS) is associated with increased risks of life-threatening infection, thromboembolism, lipid abnormalities, and malnutrition. The aim of the management of INS in children is to induce and maintain complete remission with resolution of proteinuria and edema without serious adverse effects of therapy. The majority of children have corticosteroid sensitive idiopathic nephrotic syndrome (CSINS), and in these children, corticosteroid therapy is the mainstay of therapy to induce remission. Data from a meta-analysis of randomized controlled trials (RCTs) indicate that prolonged courses of corticosteroids (up to 7 months) given in the first episode of CSINS reduce the risk of relapse. Nevertheless, many children relapse, and are at risk of corticosteroid toxicity if frequent courses of corticosteroids are required. Data from RCTs supports the use of alkylating agents (cyclophosphamide, chlorambucil), cyclosporine, and levamisole in these children to achieve prolonged periods of remission. The specific management of corticosteroid-resistant idiopathic nephrotic syndrome (CRINS) is more difficult since few therapies are consistently effective, and data from RCTs are limited. In such children, cyclosporine, alkylating agents, and high dose intravenous methylprednisone may be used. In addition to specific therapies for INS, supportive therapies are commonly used to control edema (loop diuretics, aldosterone antagonists, albumin infusions, angiotensin-converting enzyme inhibitors), reduce the risk of infection (antibacterials, pneumococcal vaccination) and thromboembolism (aspirin [acetylsalicylic acid]), and to control hyperlipidemia (HMG-CoA reductase inhibitors), especially in children with CRINS.