Encapsulating peritoneal sclerosis in paediatric peritoneal dialysis patients: the experience of the Italian Registry of Pediatric Chronic Dialysis.

BACKGROUND: Paediatric literature about encapsulating peritoneal sclerosis (EPS) is limited and comes primarily from anecdotic experiences. In this study, we described the incidence and characteristics of EPS in a large paediatric chronic peritoneal dialysis (CPD) patient population. METHODS: We reviewed files of patients starting CPD at <16 years of age, recorded from January 1986 to December 2011 by the Italian Registry of Pediatric Chronic Dialysis (n = 712). Moreover, in December 2011, a survey was performed involving all the Italian Pediatric Nephrology Units to report such EPS cases that occurred after CPD withdrawal. RESULTS: Fourteen EPS cases were reported, resulting in a prevalence of 1.9%. The median age of EPS cases was 4.8 years (range 0.6-14.4) at the start of CPD and 14.3 years (6.5-26.8) at EPS diagnosis. Eleven EPS cases received CPD for longer than 5 years. At diagnosis, nine patients were still on CPD, two were on haemodialysis and three were transplanted. In eight patients, the primary renal disease was represented by glomerulopathy, mainly focal segmental glomerulosclerosis (n = 5). In the last 6 months prior to CPD discontinuation, 10 patients were treated with solutions containing more than 2.27% glucose. Peritonitis incidence was 1:26.8 CPD-months, similar to that calculated in children >12 months of age from the same registry (1:28.3 CPD-months). The mortality rate was 43%. A more aggressive course and an association with calcineurin inhibitors were observed in transplanted patients. CONCLUSIONS: Surveillance for EPS should be maintained in high-risk children who received long-term PD even after years from CPD withdrawal.

Peritoneal dialysis in infants: the experience of the Italian Registry of Paediatric Chronic Dialysis.

BACKGROUND: Although chronic peritoneal dialysis (CPD) is considered the replacement therapy of choice for infants with end-stage renal failure, many questions persist about treatment risks and outcomes. METHODS: We present data on 84 infants who started CPD at <1 year of age; these patients represent 12% of the total population of the Italian Registry of Paediatric Chronic Dialysis. We analysed patient records from all children consecutively treated with CPD between 1995 and 2007 in Italy. Growth data analysis was performed only in infants with complete auxological parameters at 0, 6 and 12 months of follow-up. RESULTS: Median age at the start of CPD was 6.9 months, weight was 6.1 kg and length 63.6 cm. In one-half of the study population diagnosis leading to renal failure was congenital nephrouropathy. Twenty-eight per cent of the children had at least one pre-existing comorbidity. The mean height standard deviation score was -1.65 at the start of CPD, -1.82 after 12 months and -1.53 after 24 months. Catch-up growth was documented in 50% of patients during dialysis. A positive correlation was observed between longitudinal growth and both exchange volume (R(2) = 0.36) and dialysis session length (R(2) = 0.35), while a negative association was found with the number of peritonitis cases (P = 0.003). Peritonitis incidence was 1:20.7 episode:CPD-months (1:28.3 in the older children from the same registry) and was significantly higher in children with oligoanuria (1:15.5 episode:CPD-months) compared to infants with residual renal function (1:37.4 episode:CPD-months). Catheter survival rate was 70% at 12 months and 51% at 24 months. Catheter-related complications were similar in infants and older children (1:20.5 versus 1:19.8 episode:CPD-months), while clinical complications were more frequent in children under 1 year of age (1:18.3 versus 1:25.2 episode:CPD-months; P < 0.05). During the follow-up period, 33 patients were transplanted (39.3%), 18 were shifted to haemodialysis (21.4%) and 8 died (9.5%). The mortality rate was 4-fold greater than in older children (2.3%). CONCLUSIONS: Our data confirm that infants on CPD represent a high-risk group; however, our experience demonstrated that growth was acceptable and a large portion was successfully transplanted. Increased efforts should be aimed at optimizing dialysis efficiency and preventing peritonitis. The higher mortality rate in infants was largely caused by comorbidities.

Hemolytic uremic syndrome: epidemiological and clinical features of a pediatric population in Tuscany.

We retrospectively analyzed etiological, pathological and clinical features of the patients with hemolytic uremic syndrome (HUS) observed in the Pediatric Nephrology Unit at AOU Meyer of Florence. From January 1997 to December 2008, 22 cases were identified, with an annual incidence of 0.05 cases per 100,000 inhabitants, and 0.34 cases per 100,000 children <15 years old. 60% of the patients were D+ and 40% were D-, with an age distribution from 12 days to 13 years. Twenty patients (90%) had oligoanuria, lasting 6.4 ± 4 days for D+ patients versus 11.8 ± 4 days for D- patients. The development of chronic kidney disease positively correlates with the initial blood pressure value, the length of oligoanuria, and hospitalization. Microbiological investigations showed an association of D+HUS with different strains of Shiga toxin-producing Escherichia coli in 54% of the cases. D-HUS was associated with complement factor H deficiency in one patient. In the other cases, the triggering factors were pertussis, urinary tract infections and upper airway infections. While clinical and prognostic features correspond with literature data, in Tuscany the annual incidence is lower, and the percentage of D-HUS patients is higher than that observed in other studies.

Inner ear abnormalities in four patients with dRTA and SNHL: clinical and genetic heterogeneity.

A significant number of patients affected by autosomal recessive primary distal renal tubular acidosis (dRTA) manifest sensorineural hearing loss (SNHL). Mutations in ATP6V1B1 are associated with early onset SNHL, whereas ATP6V0A4 mutations have been described in dRTA and late-onset SNHL. Enlarged vestibular aqueduct (EVA) was described in patients with recessive dRTA and SNHL, and recently, this abnormality has been associated with mutations in the ATP6V1B1 gene. In our study, we evaluated the presence of inner-ear abnormalities in four patients affected by dRTA and SNHL, characterized by molecular analysis. Two patients affected by severe dRTA with early onset SNHL showed the same mutation in the ATP6V1B1 gene and bilateral EVA with a different degree of severity. The other two presented similar clinical manifestations of dRTA and different mutations in the ATP6V0A4 gene: one patient, showing EVA, developed an early SNHL, whereas in the other one, the SNHL appeared in the second decade of life and the vestibular aqueduct was normal. Our study confirms the association of EVA and mutations in the ATP6V1B1 gene and demonstrates that mutations in the ATP6V0A4 gene can also be associated with EVA probably only when the SNHL has an early onset. The pathophysiology of SNHL and EVA are still to be defined.

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.

Peritoneal dialysis in neonates with inborn errors of metabolism: is it really out of date?

Peritoneal and extracorporeal dialysis are used to treat newborns affected by inborn errors of metabolism to minimize the effects of the acute accumulation of neurotoxic metabolites that can produce irreversible and severe neurological damage and even death. In recent papers, extracorporeal dialysis has been described as more effective than peritoneal dialysis in improving the prognosis in newborns with inborn errors of metabolism and hyperammonemia. However, it appears that the outcome is primarily related to the duration of neonatal hyperammonemic coma. Here we report seven newborns with hyperammonemia caused by inborn errors of metabolism (five with organic acidemias, two with urea-cycle disorders). They received dietetic and pharmacological treatment as well as peritoneal dialysis. Four of the five patients with organic acidemia survived with and without mild neurological impairment (follow-up 3.5-10 years). One died from bacterial sepsis after peritoneal dialysis was discontinued and the peritoneal catheter was removed. One of the two patients affected by urea-cycle disorders, a boy, died during the neonatal period, and the other, a girl, died at the age of 13 months due to severe neurological damage. Our results demonstrate that peritoneal dialysis may still be an effective treatment for neonatal hyperammonemia caused by inborn errors of metabolism. Furthermore, peritoneal dialysis can be administered quickly and easily in all settings, clearly an advantage when fast intervention is so crucial.

Effect of carnitine supplementation on lipid profile and anemia in children on chronic dialysis.

We prospectively evaluated the effects of L-carnitine supplementation on plasma free carnitine (FC) levels, serum lipid profile, and erythropoietin (rhEPO) requirement in 24 children treated with peritoneal dialysis (PD; n=16) or hemodialysis (HD; n=8). The study was divided into a 3-month observation period, and a 3-month treatment period during which patients received 20 mg/kg per day of L-carnitine given orally. Clinical, biochemical, and hematological data were collected every 3 months. FC levels were measured in plasma and peritoneal dialysate by tandem mass spectrometry. There were no statistically significant changes in lipid levels, hemoglobin, or rhEPO requirements during the course of the study. Fifteen patients (13 PD, 2 HD) had plasma FC levels measured before and after treatment; FC levels increased from 32.1 +/- 14.1 micromol/l to 80.9 +/- 38.7 micromol/l (P<0.001). In PD patients, dialysate FC losses increased from 106 +/- 78 micromol/day at baseline to 178 +/- 119 micromol/day after supplementation. Positive correlations between FC plasma levels and dialysate levels (R=0.507) or daily excretion (R=0.603) were found after treatment. In our case series, an oral dose of 20 mg/kg per day of L-carnitine restored FC levels and produced a positive carnitine balance with no significant effects on hematological parameters or lipid profile over a 3-month period. Prolonged treatment duration may be required to obtain significant results.

A prospective multicentre study of the nutritional status in children on chronic peritoneal dialysis.

The anthropometry-bioimpedance analysis-nutrition (ABN) score is a recently proposed objective method of assessing malnutrition in children on chronic peritoneal dialysis (CPD) that uses nine parameters based on anthropometry, skinfold thickness and bioimpedance analysis. The aim of this prospective, cross-sectional study was to apply it to children treated with CPD in seven Italian paediatric nephrology centres, with a score of < 10.33 (the 3rd percentile in a population of 264 healthy children) classifying the children as malnourished. The other considered parameters were age, age at the start of dialysis and duration of dialysis; serum haemoglobin, urea, creatinine, total protein, albumin, transferrin, bicarbonate and C-reactive protein; residual urine output; urinary and peritoneal creatinine clearance; and daily protein and energy intake. The study enrolled 43 patients (mean age 10.2 +/- 4.2 years), 21 of whom (48.8%) had an ABN score of < 10.33: 15 with mild, five with moderate, and one with severe malnutrition. The malnourished patients started CPD at a younger age (P < 0.05) and had a longer duration of dialysis (P < 0.01), and a significant worsening in nutritional status was observed in those treated for more than 12 months of dialysis; they also had significantly lower serum albumin, creatinine and haemoglobin levels. In conclusion, protein-calorie malnutrition is common in children receiving CPD. A younger age at the start of dialysis and a longer duration of treatment are clear risk factors, and counterbalance the long-term viability of CPD in paediatric age.

Hypokalemic rhabdomyolysis in a child with Bartter's syndrome.

Hypokalemia represents a rare cause of rhabdomyolysis. Some reports have described a few adult patients affected by Bartter's syndrome and Gitelman's syndrome with rhabdomyolysis due to severe hypokalemia. We report the first pediatric patient with Bartter's syndrome in whom rhabdomyolysis developed when her plasma potassium level was less than 2 mEq/l. Prompt intravenous fluid and potassium prevented tubular damage and acute renal failure. We recommend determining serum creatine phosphokinase in all patients affected by Bartter's syndrome and profound hypokalemia.

A multicenter experience on patient and technique survival in children on chronic dialysis.

In this study we compared patient and technique survival of 163 new hemodialysis (HD) patients (age 11.4+/-3.1 years) and 295 peritoneal dialysis patients (7.7+/-4.8 years. P< 0.001), treated in 23 dialysis centers participating in the Italian Registry of Pediatric Chronic Peritoneal Dialysis (CPD) during the years 1989-2000. Three HD (1.8%) and 17 CPD (5.8%) patients died; the overall average death rate was 9.8/1,000 patient-years in HD and 29.8/1,000 patient-years in CPD patients. No statistically significant difference in patient survival between CPD and HD was found, while the survival of 102 CPD children younger than 5 years at the start of dialysis was lower ( P=0.0001) than that of 193 CPD and 160 HD patients aged 5-15 years. We registered 12 modality failures among HD (7.4%) patients and 44 among CPD (14.9%) patients. The main causes were vascular access failure and patient choice in HD, and infection in CPD patients. Technique survival was lower ( P=0.007) in CPD than in HD patients; a statistically significant difference ( P=0.01) was also observed between both the 0- to 5- and the 5- to 15-year-old CPD patients and the HD patients aged 5-15 years. Logistic regression analysis confirmed age at initiation of dialysis to be a predictor of patient death ( P=0.0001) in the whole patient population, and of technique failure in HD ( P=0.006) but not in CPD patients ( P=0.16).

COL4A3/COL4A4 mutations: from familial hematuria to autosomal-dominant or recessive Alport syndrome.

UNLABELLED: COL4A3/COL4A4 mutations: From familial hematuria to autosomal-dominant or recessive Alport syndrome. BACKGROUND: Mutations of the type IV collagen COL4A5 gene cause X-linked Alport syndrome (ATS). Mutations of COL4A3 and COL4A4 have been reported both in autosomal-recessive and autosomal-dominant ATS, as well as in benign familial hematuria (BFH). In the latter conditions, however, clinical features are less defined, few mutations have been reported, and other genes and non-genetic factors may be involved. METHODS: We analyzed 36 ATS patients for COL4A3 and COL4A4 mutations by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) and direct sequencing. Sporadic patients who had tested negative for COL4A5 mutations were included with typical cases of autosomal recessive ATS to secure a better definition of the phenotype spectrum. RESULTS: We identified seven previously undescribed COL4A3 mutations: in two genetic compounds and three heterozygotes, and one in COL4A4. In agreement with the literature, some of the mutations of compound heterozygotes were associated with microhematuria in healthy heterozygous relatives. The mutations of heterozygous patients are likely dominant, since no change was identified in the second allele even by sequencing, and they are predicted to result in shortened or abnormal chains with a possible dominant-negative effect. In addition, both genes showed rare variants of unclear pathogenicity, and common polymorphisms that are shared in part with other populations. CONCLUSIONS: This study extends the mutation spectrum of COL4A3 and COL4A4 genes, and suggests a possible relationship between production of abnormal COL IV chains and dominant expression of a continuous spectrum of phenotypes, from ATS to BFH.