Nephrotic Syndrome: A Review

Nephrotic syndrome (NS) is characterized by hypoalbuminemia, severe proteinuria, and peripheral edema, frequently in conjunction with hyperlipidemia. Individuals usually show symptoms of weariness and swelling, but no signs of serious liver damage or cardiac failure. With characteristic medical symptoms and evidence of hypoalbuminemia and severe proteinuria, NS can be diagnosed. The majority of NS episodes are classified as unexplained or primary; the most prevalent histopathological subgroups of primary NS in people are focal segmental glomerulosclerosis and membraneous nephropathy. Thrombosis of the veins with high cholesterol levels is a significant NS risk. Acute renal damage and infection are further possible side effects. The pathobiochemistry of NS involves alterations in genes that affect the selectivity of the kidneys and abnormalities in proteins related to podocytes. Understanding the molecular mechanisms that influence these processes is crucial to developing specific and targeted therapeutic approaches. The need for invasive renal biopsies throughout the diagnosis process may be lessened by the development of non-invasive nephrotic syndrome biomarkers, such as microRNAs. Corticosteroids are frequently used as the initial line of defense in NS treatment. However, some individuals need other treatments since a resistant type of NS also exists. The use of calcineurin inhibitors, mycophenolate mofetil, and rituximab is mentioned in the text, along with current research to identify safer and more efficient therapeutic choices. The complicated kidney condition NS has several underlying causes and symptoms. For the diagnosis of this ailment as well as the creation of focused therapies, an understanding of the pathophysiology and the identification of possible biomarkers are essential.

Influence of Age, Time, and Peritonitis on Peritoneal Transport Kinetics in Children

Objective

To evaluate peritoneal transport kinetics and its changes over time in children with and without peritonitis, and to record possible differences between children under and over 5.0 years of age.

Design

A prospective study. The patients underwent a 4hour peritoneal equilibration test (PET) comprising 2.27% dextrose with a dialysate fill volume of 1000 mL/m2 of body surface area (BSA), at baseline and after a mean of 0.8: I: 0.4 years of uninterrupted dialysis.

Patients

We investigated 28 patients on maintenance peritoneal dialysis at baseline; 10 were under 5.0 years of age. The final PET was performed in 21 patients.

Main Outcome Measures

Peritoneal equilibration rates for urea (U), creatinine (C), glucose (G), sodium, potassium, phosphate, and albumin (A) were measured. Initial and final peritoneal equilibration rates were compared. Mass transfer area coefficients (MTAC) were calculated for urea, creatinine, glucose, and albumin. Residual dialysate volume was determined.

Results

Median age at first PET was 7.6 years (range 0.3 -16.6 yr). The mean (±1 SD) 4-hour dialysate-to-plasma (DIP) ratios for U, C, and A were 0.92:1: 0.05,0.70 ± 0.12, and 0.014: I: 0.007, respectively. The mean 4-hour DIDo ratio for G was 0.32: I: 0.10. DIP and DIDo results were similar in the two age groups, and peritoneal membrane function remained stable over the study period. Mean MTAC (:1:1 SD) values were: U, 22.3: I: 4.8; C, 10.9: I: 4.1; G, 11.1: I: 3.3; and A, 0.07: I: 0.03. MTAC data were similar in the two age groups and no significant changes occurred during the study period.

Conclusions

When the volume tested in children is proportional to BSA, the solute DIP ratios seem to be age-independent. Our data provide evidence that in pediatric patients MTAC is also age-independent.

Exit-Site Infection in Children on Peritoneal Dialysis: Comparison of Two Types of Peritoneal Catheters

Objective

To review our experience with two types of peritoneal catheters, the standard Tenckhoff catheter and the swan-neck presternal catheter (SNPC).

Design

A retrospective study was undertaken to compare exit-site infection (ESI) rates using two types of peritoneal catheters in children.

Setting

Medical University of Warsaw, Warsaw, Poland.

Patients

During the past 10 years, 60 peritoneal catheters were implanted in 50 children with end-stage renal failure: 46 straight, double-cuffed Tenckhoff in 37 children (mean age 11.8 ± 4.2 years, range 3.1 – 18.5 years), and 14 presternal in 13 children (mean age 10.6 ± 5 years, range 0.3 – 17.7 years). The SNPCs were used in special clinical situations such as recurrent ESI with previous abdominal peritoneal catheters, obesity, presence of ureterocutaneostomies, use of diapers, and young age. For the statistical analysis, only the first catheter placed in each child was chosen: 34 standard Tenckhoff catheters and 9 SNPCs.

Intervention

In all children, peritoneal catheters were implanted surgically under general anesthesia by one surgeon; uniform operative technique and perioperative management was used.

Results

The mean observation time for 46 standard Tenckhoff catheters was 23.8 ± 21.1 months, and for 14 SNPCs 25.1 ± 27.0 months. The ESI rate was 1/17.4 patient-months (0.69 episodes/year) for Tenckhoff catheters and 1/70.2 patient-months (0.17 episodes/year) for SNPCs. The observed differences in ESI rates between the groups reported did not achieve statistical significance.

Conclusions

The risk of ESI may be lower with presternal catheters. Confirmation of these findings requires further prospective clinical investigation in large numbers of patients.

Chronic Peritoneal Dialysis Catheters in Children: A Fifteen-year Experience of the Italian Registry of Pediatric Chronic Peritoneal Dialysis

Objective

To analyze data on 503 chronic peritoneal dialysis (CPD) catheters implanted between 1986 and 2000 in pediatric patients enrolled in the Italian Registry of Pediatric Chronic Peritoneal Dialysis (the Registry), comparing three different time periods: 1986 – 1990, 1991 – 1995, and 1996 – 2000.

Design

Retrospective study.

Setting

23 dialysis centers participating in the Registry.

Methods

Data were collected from questionnaires filled in every year. The information for each peritoneal catheter included type, site and technique of insertion, exit-site orientation, exit-site care, complications, survival, and reason for removal.

Patients

503 catheters were implanted in 363 pediatric patients aged younger than 15 years at the start of CPD: 97 catheters in patients under 2 years of age, 67 in patients aged 2 – 5 years, and 339 in patients over 5 years of age. Mean patient age at onset of CPD was 8.0 ± 5.1 years. All catheters were surgically implanted and omentectomy was performed in 82.4% of cases. The catheters used were Tenckhoff [468 (93.0%): 443 double cuff, 25 single cuff] and double-cuffed Valli [35 (7.0%)]. The entry site was in the midline in 153 cases (30.4%) and paramedian in 350 (69.6%).

Results

During 9048 dialysis-months we observed 451 catheter-related complications, yielding an incidence of 1 episode/20.1 CPD-months: 330 catheter infections (exit-site and/or tunnel infections), 26 leakages, 26 dislocations, 24 obstructions, 22 cuff extrusions, 6 hemoperitoneums, 17 others. 171 catheters were removed due to catheter-related causes; exit-site and/or tunnel infections were the main cause for removal (75.4%), followed by obstruction, dislocation, outer-cuff extrusion, and leakage. Younger children (< 2 years) had a higher risk of infectious causes of catheter removal compared to children aged 2 – 5 years ( p = 0.004) and over 5 years of age ( p = 0.002). During the 15-year observation period, a significant reduction in the incidence of leakage was observed and risk of leakage was lower in catheters with paramedian entry site compared to catheters with midline entry site. Removal and replacement of peritoneal catheters during the same surgical operation was performed in 76.3% of catheter removals. Catheter survival rate was 78.1% at 12 months, 58.5% at 24 months, 43.8% at 36 months, and 34.6% at 48 months. No difference in catheter survival was observed in younger children (< 2 years) compared with the two other age groups: < 2 years versus 2 – 5 years hazard ratio 0.7, 95% confidence interval (95%CI) 0.4 – 1.2; < 2 years versus > 5 years hazard ratio 0.8, 95%CI 0.5 – 1.1.

Conclusions

In this survey, we observed better catheter survival in comparison with data reported by the Registry in 1998. Catheter survival improved especially in younger children (< 2 years), a group that previously had a decreased catheter survival rate compared to older age groups. In addition to the progressive increase in experience acquired by dialysis centers, this upward trend may also be related to greater use of double-cuffed catheters, with paramedian exit site, and a higher frequency of omentectomy.

Congenital nephrotic syndrome: is early aggressive treatment needed? Yes

Congenital nephrotic syndrome (CNS) was primarily considered one disease entity. Hence, one treatment protocol was proposed in the beginning to all CNS patients. Today, with the help of gene diagnostics, we know that CNS is a heterogeneous group of disorders and therefore, different treatment protocols are needed. The most important gene defects causing CNS are NPHS1, NPHS2, WT1, LAMB2, and PLCE1. Before active treatment, all infants with CNS died. It was stated already in the mid-1980s that intensive medical therapy followed by kidney transplantation (KTx) should be the choice of treatment for infants with severe CNS. In Finland, early aggressive treatment protocol was adopted from the USA and further developed for treatment of children with the Finnish type of CNS. The aim of this review is to state reasons for "early aggressive treatment" including daily albumin infusions, intensified nutrition, and timely bilateral nephrectomy followed by KTx at the age of 1-2 years.

Parent-child and spousal relationships in families with a young child with end-stage renal disease

BACKGROUND

End-stage renal disease (ESRD) leads to the need for dialysis and renal transplantation (Tx). Peritoneal dialysis (PD) of young children is normally performed at home by the parents and affects the whole family. We studied the coping of families with a young child with ESRD by interviewing the parents of 19 children.

METHODS

The spousal and parent-child relationships were assessed by using the Psychosocial Assessment of Childhood Experiences (PACE) and the Brief Measure of Expressed Emotion, respectively. A control group of 22 families with a healthy child was used for the parent-child relationship evaluation.

RESULTS

The spousal relationship at the start of PD was good or fairly good in most of the families and remained good in half of the families following renal Tx. Lack of support from close relatives and renal Tx were associated with a poorer relationship quality. Almost all parents expressed much or fairly much emotional warmth towards the child throughout the study, but there was a trend towards increased criticism over time. No differences in the degree of expressed warmth or criticism were noted between the index parents and controls.

CONCLUSIONS

Overall, the study families appeared to cope well despite the serious illness of their child and the demands of the treatments.

Neurological development in 21 children on peritoneal dialysis in infancy

Few studies have focused on the neurodevelopment of infants on peritoneal dialysis (PD). Infants are the most demanding patient group on PD and thus are vulnerable to neurological sequelae. We studied 21 patients <2 years of age (mean 0.59 years) at onset of PD. They were evaluated by a neurologist, otologist, physiotherapist, and occupational therapist during PD. Neuropsychological tests were collected from all patients at least 5 years old, and the brain images were reviewed. Eleven patients (52%) had a pre- or neonatal problem or comorbidity as risk factor for their development at onset of PD. All infants tolerated PD well. At the end of the study, 71% had some neurological abnormality, 29% a major impairment (all with predialysis risk factors), and 43%  a minor one. Brain infarcts were detected in four patients (19%) and other ischemic lesions in three (14%). Three patients (14%) developed hearing defect. Mortality rate was 5%. PD is a safe treatment modality for end-stage renal failure in infants. Some patients had risk factors for development, but their neurological problems did not progress during PD. Patients without risk factors tolerated PD well without major neurological sequelae.

Normal growth and intravascular volume status with good metabolic control during peritoneal dialysis in infancy

The most demanding patient population on peritoneal dialysis (PD) consists of children under 2 years of age. Their growth is inferior to that of older children and maintaining euvolemia is difficult, especially in anuric patients. In this prospective study reported here, we enrolled 21 patients <2 years of age (mean 0.59 years) at onset of PD and monitored their uremia parameters and evaluated their nutrition. Since no good instrument currently exists for estimating intravascular volume status, we used traditional blood pressure measurements, echocardiography, and N-terminal atrial natriuretic peptide measurements. Growth was compared with midparental height. Metabolic control was good. Long-term hypertension was seen in 43% of the patients, but left ventricular hypertrophy decreased during the study period. Mean weekly urea Kt/V was 3.38 +/- 0.66 and creatinine clearance was 49 +/- 20 L/week per 1.73 m(2). Catch-up growth was documented in 57% of the patients during PD. However, these children did not attain their midparental height at the end of PD at a mean age of 1.71 years. Although favorable metabolic control and good growth were achieved during PD, these children lagged in term of their midparental height. We conclude that several instruments are needed for determining the management of intravascular volume status and that the control of calcium-phosphorus status is demanding.

Intermittent or daily administration of 1-alpha calcidol for nephrectomised infants on peritoneal dialysis?

Secondary hyperparathyroidism and renal osteodystrophy are major problems in patients with end-stage renal failure and may result in poor growth in children on dialysis. Whether vitamin D sterols should be given intermittently or daily remains a controversial issue. We studied 16 bilaterally nephrectomised infants with congenital nephrosis of the Finnish type (median age 0.54 years), all on peritoneal dialysis. Nine of them were receiving intermittent 1-alpha calcidol therapy and seven daily 1-alpha calcidol therapy. The target serum parathyroid hormone (PTH) level was 2-3 times the upper limit of normal (ULN). There were no statistically significant differences in PTH values between the groups (1.7-times vs 0.5-times the ULN at 3 months and 3.1-times vs 3.4-times the ULN at 6 months, respectively). The required weekly doses of 1-alpha calcidol were low, and there were no significant differences between the intermittent and daily groups (0.06 microg/kg vs 0.04 microg/kg at 3 months and 0.09 microg/kg vs 0.05 microg/kg at 6 months, respectively). The infants on intermittent 1-alpha calcidol showed significant catch-up growth during dialysis after nephrectomy relative to the infants on daily 1-alpha calcidol (-1.6 SD to -0.7 SD vs -1.4 SD to -1.0 SD, respectively; P < 0.05). Our results indicate that either intermittent or daily vitamin D analogue therapy, if started early, will prevent secondary hyperparathyroidism equally well in children on peritoneal dialysis (PD), but intermittent therapy might be more favourable for growth.

[Evaluation of therapeutic strategies in congenital nephrotic syndrome of the Finnish type]

INTRODUCTION

Congenital nephrotic syndrome of the Finnish type (CNFS) is caused by mutations in the nephrin gene. This disease manifests as massive proteinuria, gross peripheral edema, and ascites during the first weeks of life. In the last few years the prognosis has improved due to new treatment strategies: antiproteinuria drugs, intensive nutrition, nephrectomy, dialysis, and renal transplantation. The aim of this study was to determine the impact of these therapeutic measures.

PATIENTS AND METHOD

We performed a descriptive retrospective epidemiological study of 12 patients diagnosed with CNSF between January 1985 and August 2005. We included patients aged less than 14 years old with massive proteinuria and generalized edema during the neonatal period, a large placenta (> 25 % of birth weight), and normal glomerular filtration rate during the first 6 months of life, in whom other causes of congenital nephrotic syndrome were ruled out.

RESULTS

The diagnosis was established after a median period of 17 days (range 6-30). The most commonly used treatments were albumin infusions (91.7 %), angiotensin-converting enzyme inhibitors (66.7 %), and indomethacin (58.3 %). Dialysis was started in 58.3 %, at a median age of 3.76 years (2.81-7.6). The main complication was acute peritonitis (85.7 %). Renal transplantation was performed in 58.3 % of the patients; of these, 71.4 % have normal renal function after a median follow-up of 3.73 years (0.8-6.3). The median plasma albumin level during the pretransplant period was 0.17 g/dL (0.12-0.28). Plasma cholesterol and triglyceride levels decreased significantly after renal transplantation (p = 0.043). Fifty percent of the patients achieved adequate height and weight for their age and gender. Mortality was 33.3 %.

CONCLUSION

Antiproteinuria drugs and intensive nutritional therapy improve clinical control and delay the start of dialysis and renal transplantation, increasing the probability of success.

Peritoneal dialysis in infants

The need for maintenance dialysis for infants is rare, but peritoneal dialysis has been the modality of choice in cases of end-stage renal failure, for technical reasons. Problems include higher mortality rates and an inferior long-term outcome compared with that in older children. Also, no internationally accepted guidelines exist for dialysis in infants. Many children on maintenance peritoneal dialysis in Finland have congenital nephrotic syndrome of the Finnish type (NPHS1), and dialysis is started during infancy. In this commentary we discuss our practice of performing peritoneal dialysis in infants and experiences gathered from the literature.

Psychosocial adjustment and quality of life after renal transplantation in early childhood

Psychosocial adjustment and quality of life has been reported good in children after a successful renal transplantation (Tx). There are, however, few reports of using standardized methods in evaluating these issues, particularly in small children. We investigated the psychosocial adjustment in 32 children at school age (mean 9.6 +/- 1.6), who had received a renal Tx under the age of 5 yr, using the Achenbach Child Behavior Checklist with data collected from both parents (CBCL) and teachers (CBCL-TRF). Health-related quality of life (HRQOL) was assessed by interviewing the children using a 17-dimensional (17D) health-related measure and compared to HRQOL of 244 normal school children. The effect of additional diseases and comorbidity on psychosocial adjustment and HRQOL was assessed. The total scores on the CBCL did not differ from normative samples of healthy children. However, somatic complaints and social problems were reported more frequently in boys, and attention problems in both boys and girls. Patients with pathological scores had significantly more comorbidity (p = 0.03) and were more often attending a special school (p = 0.007) than patients with normal scores. The global 17D HRQOL index was significantly lower than measured in healthy controls (94 +/- 5 for controls and 85 +/- 7 for patients, p < 0.0001). It is of crucial importance to further minimize the risk factors leading to comorbidity in children after Tx. HRQOL assessment by the children themselves can be used to direct interventions and support the children's psychosocial adjustment.

Management of congenital nephrotic syndrome

We reviewed the medical records of seven children with congenital nephrotic syndrome (CNS) treated by unilateral nephrectomy, captopril, and indomethacin since 1990. Clinical response to the treatment was analyzed using the Students' t-test. After a median period of 54 months (range 36-88 months) follow-up, five patients were alive at a median age of 74 (range 43-88) months. Median (range) plasma albumin rose from 11 (6-17) g/l at the start of treatment to 18 (15-22) g/l and 21 (18-25) g/l after 6 and 12 months treatment, respectively ( P=0.001 and P=0.0006). Albumin infusions per patient per month decreased from 7 (0-18) to 0 (0-30) in the 6 months post treatment ( P=0.017). The median (range) height standard deviation scores at 12 months and 30 months from onset of treatment were -1.56 (-2.96 to 0.41) and -1.43 (-2.40 to 0.90), respectively. In conclusion, management of CNS with captopril and indomethacin therapy in combination with unilateral nephrectomy achieves significant improvements in plasma albumin and reduces the need for albumin infusions and time in hospital, while growth is maintained. Second nephrectomy, dialysis, and transplantation can be delayed until the 3rd year of life or longer.

Neurodevelopmental outcome in high-risk patients after renal transplantation in early childhood

Patient and graft survival rates of pediatric renal transplant recipients are currently excellent, but there are few reports regarding the long-term neurodevelopmental outcome after renal transplantation (Tx) in early childhood. Children with renal failure from infancy would be expected to have a less favorable developmental prognosis. We report the neurodevelopmental outcome in 33 school-age children transplanted between 1987 and 1995 when < 5 yr of age. We prospectively performed a neurological examination, magnetic resonance imaging (MRI) of the brain, electroencephalograms (EEGs), audiometry, and neuropsychological tests (NEPSY), and measured cognitive performance (WISC-R); we related these results to school performance and to retrospective risk factors prior to Tx. Twenty-six (79%) children attended normal school and 76% had normal motor performance. Six of the seven children attending a special school had brain infarcts on MRI. The EEG was abnormal in 11 (35%), and five (15%) received anti-convulsive treatment after Tx. Sensorineural hearing loss was documented in six patients. The mean intelligence quotient (IQ) was 87, and 6-24% showed impairment in neuropsychological tests. The children attending a special school had been more premature, but had not had a greater number of pre- or neonatal complications. They had experienced a greater number of hypertensive crises (p = 0.002) and seizures (p = 0.03), mainly during dialysis, but the number of septic infections and the mean serum aluminum levels were not significantly greater than in the children with normal school performance. In these previously lethal diseases, the overall neurodevelopmental outcome is reassuring. However, it is of crucial importance to further minimize the risk factors prior to Tx.

Surgical aspects of dialysis in newborns and infants weighing less than ten kilograms

PURPOSE

Renal failure occurs in children with moderate frequency. Surgical aspects of establishing and maintaining dialysis access in small infants are exceptionally challenging. The purpose of this review is to evaluate the authors' experience with dialysis access for infants less than 10 kg, particularly with respect to the surgical care required.

METHODS

A retrospective review was conducted between 1991 and 1999 of all pediatric dialysis patients weighing 10 kg or less (n = 29). Age at start of dialysis, duration of dialysis, modes of dialysis, and complications specific to peritoneal (PD) and hemodialysis (HD) were examined.

RESULTS

The mean age at start of dialysis was 10.4 months and continued for an average duration of 16.3 months. Seventy-two percent of all patients required both modes of dialysis. HD and PD duration averaged 7.8 and 10.5 months, respectively. Catheter durability was 3.1 and 4.5 months per catheter for HD and PD, respectively. There was no significant difference in complications when comparing HD and PD. Patients who weighed 5 to 10 kg had significantly longer PD catheter durability than patients 0 to 5 kg (P = .001). Forty-one percent of patients terminated dialysis after transplantation, whereas 24% died awaiting transplantation.

CONCLUSION

Despite a large number of operations required, infants less than 10 kg can be bridged successfully, by surgical intervention and subsequent dialysis, to transplantation.