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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.

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.

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.

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.

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).

The results of the first 3 years' collaboration of the Italian Registry of Paediatric Chronic Peritoneal Dialysis (CPD) (1986-1988) are presented. This Registry acquired data on the majority of the paediatric patients treated with CPD in Italy, thus providing a national picture in a field where few nationwide surveys are available. Patients of less than 15 years of age at the start of dialysis were enrolled and clinical data collected until the age of 19 years. The number of nephrological paediatric centres participating in the Registry increased from 7 in 1986 to 11 in 1988. The total number of patients on CPD was 70 and the percentage of dialysed children treated with CPD ranged from 40.2% to 43.6%. Data on 89 peritoneal catheters were collected: during 1417 dialysis-months 70 catheter-related complications were observed (1:20.8 dialysis-months); actuarial catheter survival was 92.7% at 6 months, 84.8% at 1 year and 68.8% at 2 years. the incidence of peritonitis changed from 1 episode every 10.9 patient-months in 1986 to 1 every 19.8 in 1988. Abdominal hernias were the other main clinical complication observed. The survival of patients was 92.5% at 3 years, while the technique survival at the same time was 84%.