Clinical experience with darbepoietin alfa (NESP) in children undergoing hemodialysis.

Darbepoietin alfa (NESP) is a new long-acting erythropoietin, with a half-life 3 times longer than the old epoietins. In the present study, we evaluated the efficacy of NESP in a group of children on hemodialysis. Seven children, five male and two female, with a mean age of 11.5 +/- 3 years and a mean weight of 34.1 +/- 11 kg, were enrolled in the study. All had been treated for at least 6 months with epoietin alfa at a mean dose of 106 +/- 76 IU/kg 3 times/week i.v. They were then given NESP at a mean dose of 1.59 +/- 1.19 microg/kg once a week i.v., according to the suggested conversion index (weekly epoietin alfa dose/200=weekly NESP dose). Anemia was evaluated at the end of a dialysis session. This was especially important for children less compliant with water restriction. Serum ferritin and percentage transferrin saturation (TSAT) were also monitored, as were dialysis efficacy (Kt/V), blood pressure, and heparin requirements. Before starting the new treatment, all patients had an adequate mean hemoglobin (Hb) level (11.19 +/- 1.7 g/dl) and an adequate iron status (TSAT 24.2 +/- 11.5, serum ferritin 220 +/- 105 mg/dl). Five of the seven patients were also treated with intravenous ferric gluconate (10-20 mg/kg per week). Six children were on antihypertensive treatment. After the 1st month of treatment, we observed an excessive increase in Hb, 12.3 +/- 1.7 g/dl, (P<0.05), with severe hypertension in the youngest two patients (Hb>13 g/dl). A short discontinuation of the medication, followed by restarting at a decreased dosage, allowed us to continue with the treatment. At the 2nd month of follow-up, a mean plasma Hb level of 12.2 +/- 1.2 g/dl was observed, with a NESP mean dose of 0.79 +/- 0.4 microg/kg per week. Steady state was reached at 3 months, with a mean Hb of 11.8 +/- 1.4 g/dl and a mean NESP dose of 0.51 +/- 0.18 microg/kg per week (P<0.05). These results persisted at 6 months of follow-up; only one child had a persistent increase in platelet level (373,000 vs. 555,000). Dialysis efficiency and heparin requirements during dialysis did not change significantly. The high efficacy of NESP allowed a consistent reduction in dosage. The suggested conversion index does not appear to be correct for pediatric patients. Our experience suggests that in this population the correct dose could be 0.25-0.75 microg/kg per week. Hypertension was the only major side effect reported. The influence of NESP on platelet proliferation needs to be further investigated. The single weekly administration of NESP could be effective and beneficial for both patients and clinicians.

Hyperhomocysteinemia and protein damage in chronic renal failure and kidney transplant pediatric patients--Italian initiative on uremic hyperhomocysteinemia (IIUH).

BACKGROUND: Plasma homocysteine, a new cardiovascular risk factor in both children and adults, is higher in chronic renal failure or kidney transplant patients. This alteration has been linked, in chronic renal failure, to plasma protein damage, represented by increased L-isoaspartyl residues. We measured plasma homocysteine levels and plasma protein damage in pediatric patients from four different Italian regions with conservatively treated renal failure; hemodialysis, continuous ambulatory peritoneal dialysis (CAPD), or transplants, to establish the presence of protein damage and the relative role of hyperhomocysteinemia. METHODS: High performance liquid chromatography (HPLC) separation measured total plasma homocysteine levels, using precolumn derivatization with ammonium 7-fluorobenzo-2-oxa-1, 3-diazole-4-sulphonate (SBD-F). Plasma protein L-isoaspartyl residues were quantitated using human recombinant protein carboxyl methyl transferase (PCMT). RESULTS: In all patient groups, homocysteine levels were significantly higher with respect to the control (Control: 6.87 +/- 0.73 microM) conservatively treated, 14.19 +/- 1.73 microM; hemodialysis, 27.03 +/- 4.32 microM; CAPD, 22.38 +/- 3.73 microM; transplanted, 20.22 +/- 2.27 microM, p < 0.001 vs. control]. Plasma protein damage was significantly higher in conservatively treated, hemodialysis (HD) and CAPD patients, while in transplant patients it was no different from the control. CONCLUSIONS: We concluded that in pediatric patients of different Italian geographical origin, plasma homocysteine levels were significantly higher in all groups with respect to healthy children; therefore contributing to the elevated cardiovascular risk present in these patients. Plasma protein L-isoaspartyl content was higher in renal failure patients, but kidney transplant patients had normal levels, indicating that this kind of protein damage relates more to the toxic action of uremic retention solutes, than to plasma homocysteine levels.

Risk factors for poor renal prognosis in children with hemolytic uremic syndrome.

Many factors have been proposed as predictors of poor renal prognosis in children with hemolytic uremic syndrome (HUS), but their role is still controversial. Our aim was to detect the most reliable early predictors of poor renal prognosis to promptly identify children at major risk of bad outcome who could eventually benefit from early specific treatments, such as plasmapheresis. Prognostic factors identifiable at onset of HUS were evaluated by survival analysis and a proportional hazard model. These included age at onset, prodromal diarrhea (D), leukocyte count, central nervous system (CNS) involvement, and evidence of Shiga toxin-producing Escherichia coli (STEC) infection. Three hundred and eighty-seven HUS cases were reported; 276 were investigated for STEC infection and 189 (68%) proved positive. Age at onset, leukocyte count, and CNS involvement were not associated with the time to recovery. Absence of prodromal D and lack of evidence of STEC infection were independently associated with a poor renal prognosis; only 34% of patients D(-)STEC(- )recovered normal renal function compared with 65%-76% of D(+)STEC(+), D(+)STEC(-) and D(-)STEC(+ )patients. In conclusion, absence of both D and evidence of STEC infection are needed to identify patients with HUS and worst prognosis, while D(-) but STEC(+) patients have a significantly better prognosis.

Congenital nephrotic syndrome of the Finnish type in Italy: a molecular approach.

BACKGROUND: Congenital nephrotic syndrome of the Finnish type (CNF) is an autosomal recessive disorder mainly caused by mutations in the nephrin gene (NPHS1). The frequency of this gene is highest in Finland but the condition occurs in all populations, with and without Finnish ancestry. The NPHS1 gene is located in the chromosomal region 19q13.1 and consists of 29 exons. METHODS: Polymerase chain reaction (PCR), restriction and sequence analyses were used to screen 15 CNF Italian patients for mutations in this gene. RESULTS: No Italian patients had the typical Finnish mutations, a 2bp deletion in exon 2 (Fin-major) and a nonsense mutation in exon 26 (Fin-minor). We found 13 mutations including deletions, insertions, nonsense and missense mutations. Seven of these have never been described before. We also found one nucleotide change in the promoter region and one common polymorphism. NPHS1 missense mutations were confirmed by analysis of a healthy control population. CONCLUSIONS: Our study provides further evidence that loss of function of the nephrin gene is the main cause of congenital nephrotic syndrome of the Finnish type in Italian patients.