Mineral metabolism management in Canadian peritoneal dialysis patients.

BACKGROUND: Abnormal mineral metabolism is associated with increased morbidity and mortality in dialysis patients. Therefore, the goal of this study was to compare a) mineral metabolism control among a cohort of Canadian peritoneal dialysis (PD) patients to K/DOQI-defined targets and b) the effect of different treatment strategies on mineral metabolism parameters. METHODS: We looked at a cohort of 317 Canadian PD patients from 9 clinics that used the PhotoGraph™ software program which tracks mineral metabolism management. Serum phosphorus (P), calcium (Ca) and intact parathyroid hormone (iPTH) values were collected for the patients. Data were categorized and analyzed by the type of phosphate binder prescribed, vitamin D use, and dosing and reimbursement criteria for the phosphate binder, sevelamer. RESULTS: The majority of patients achieved K/DOQI-set targets for serum P. Patients who resided in Quebec (QC), which had greater access to sevelamer, had lower mean concentrations of P and Ca, were less likely to take Ca-based phosphate binders (CBBs) exclusively and were exposed to less exogenous Ca than in Ontario (ON). CONCLUSION: Availability of the phosphate binder sevelamer and reduced doses of elemental Ca were associated with more mineral metabolism parameters within suggested target ranges. Further studies that focus on patient outcomes are warranted.

Idiopathic hypercalcemia in infants with renal dysplasia.

BACKGROUND: We have observed infants with renal dysplasia who developed sustained hypercalcemia, without vitamin D or calcium supplementation (idiopathic). This has not been previously described. OBJECTIVES: 1) Define incidence, severity and duration of idiopathic hypercalcemia in infants with renal dysplasia below 12 months of age. 2) Evaluate phosphate, parathyroid hormone (PTH) and vitamin D levels in these infants. METHODS: A retrospective study was conducted from June 2005 to June 2008. Patients receiving calcium-containing phosphate binders or daily supplemental vitamin D in excess of 400 IU were excluded. Hypercalcemia was defined as at least three corrected calcium values above normal lab values for age, in a one-week interval. RESULTS: 15 of 99 (15%) infants with renal dysplasia had hypercalcemia. All were males; 10/15 (67%) were below one month of age at presentation; 9/15 (60%) had posterior urethral valves (PUV). Mean hypercalcemia duration was 5.2 ± 6.0 months. Mean corrected calcium was 3.07 mmol/l (12.3 mg/dl). Only 3/10 infants had elevated PTH levels. None had elevated phosphate levels and only 1/8 patients who had 25-hydroxyvitamin D measured had an elevated level. CONCLUSIONS: Idiopathic hypercalcemia in infants with renal dysplasia is common. Neonates and those with PUVs are at greatest risk. Most have normal levels of 25-hydroxyvitamin D, phosphate and PTH.

Maintenance intravenous iron therapy in pediatric hemodialysis patients.

Iron supplementation is required for optimal response to erythropoietin (EPO) in hemodialysis patients. This is due to blood lost in the dialysis tubing after dialysis and the increased demand for iron by EPO therapy. Maintenance intravenous (IV) iron was administered according to a standardized protocol to pediatric patients on hemodialysis in our institution. The effect of this protocol on EPO dose, iron indices, anemia, and medication costs was evaluated. Data on two groups of patients were retrieved from the health records. Group 1 (n=14) consisted of patients treated in the 18 months prior to the protocol. These patients received oral iron supplements and occasional IV iron. Group 2 (n=5) consisted of all patients treated with the IV iron protocol. There was no difference in clinical characteristics and mean values for monthly hemoglobin, serum iron, ferritin, and transferrin saturation between groups. The dose of EPO was significantly reduced in group 2 compared with group 1 (193.9 +/- 121.4 vs. 73.9 +/- 39.0 units/kg per week, P<0.05). Medication costs were reduced by 26% in group 2. No significant adverse events were seen. Maintenance IV iron reduced the dose of EPO required to maintain blood hemoglobin levels. Our results also suggest that maintenance IV iron is a more-economic method of iron supplementation for pediatric hemodialysis patients.

Can the DOQI guidelines be met by peritoneal dialysis alone in pediatric patients? Dialysis Outcomes Quality Initiative.

DOQI guidelines recommend minimal standards for automated peritoneal dialysis (APD), with a weekly Kt/V of 2.1 and creatinine clearance (Ccr) of 63 l/1.73 m2. The purpose of this study was to assess if the DOQI guidelines could be met by dialysis alone in children on PD. Dialysis clearance studies were retrospectively analyzed in 20 pediatric patients on APD, all with a dwell volume of at least 1,000 ml/m2. Mean dialytic Kt/V was 2.0; only 45% had a Kt/V above the recommended 2.1. Mean dialytic Ccr was 43.5 l/week per 1.73 m2; only 10% achieved a Ccr above the recommended 63 l/week per 1.73 m2. Despite the significant correlation between total therapy volume (TTV) and both Kt/V and Ccr, only 2 of 10 patients with a TTV over 10 l/m2 per day reached the target Ccr. All patients had currently recommended dwell volumes, therapy times, and nocturnal cycles, but DOQI guidelines were difficult to achieve with dialysis alone. Strict adherence to DOQI guidelines in anephric pediatric PD patients may result in changing dialysis modality. However, without evidence of a correlation between delivered dose of dialysis and improved outcome, adequate dialysis should not be assessed by only measuring Kt/V and Ccr.

Manifestations and treatment of Schimke immuno-osseous dysplasia: 14 new cases and a review of the literature.

UNLABELLED: Schimke immuno-osseous dysplasia (SIOD) is a rare autosomal recessive spondylo-epiphyseal dysplasia. The characteristic features of SIOD include 1) short stature with hyperpigmented macules and an unusual facies, 2) proteinuria with progressive renal failure, 3) lymphopenia with recurrent infections, and 4) cerebral ischaemia. Although 25 patients have been reported with this disorder, the clinical course and phenotype of SIOD are not well characterized. This report summarizes the clinical findings, course and treatment of reported patients and includes 14 additional patients with SIOD. We emphasize the high incidence of cerebral ischaemia and ocular abnormalities, define the high incidence of thyroid dysfunction and blood cytopenia, and confirm the absence of effective and durable medical therapies. CONCLUSION: Schimke immuno-osseous dysplasia is a multi-system autosomal recessive disorder with variable expression that affects the skeletal, renal, immune, vascular, and haematopoietic systems. Medical therapy is limited especially for more severely affected individuals.

Efficacy of gastrostomy feeding in infants and older children receiving chronic peritoneal dialysis.

OBJECTIVE: To assess the efficacy of supplemental gastrostomy tube (g-tube) feeding in infants and children receiving chronic peritoneal dialysis (CPD). DESIGN: Retrospective observational study. SETTING: Pediatric nephrology division of tertiary care center. PATIENTS: Fifteen patients undergoing g-tube insertion while receiving CPD were included in the study, and were subdivided, on the basis of age, into the following groups: infants (< or = 2.5 years, n = 8); older children (> 2.5 years, n = 7). MAIN OUTCOME MEASURES: Assessment of the effect of CPD and g-tube feeding on statural growth assessed by height standard deviation score (SDS) and percentage weight-for-height, and measured anthropometric variables including triceps skinfold thickness (TSF), midarm muscle circumference (MAMC), and midarm mean circumference (MAC). Assessment of the effects of CPD and g-tube feeding on measured biochemical variables including total protein, albumin, cholesterol, triglycerides, and high density lipoprotein. RESULTS: No significant change in height SDS was observed; however, the reported continuing decline in height SDS in infants was arrested. Percentage weight-for-height increased significantly in infants at 6 months (p = 0.008) and 12 months (p = 0.006) following initiation of g-tube feeding. An increase was also observed in the older child group, being significant at 12 months (p = 0.031) following g-tube insertion. Increases in all anthropometric variables occurred in the infant group during CPD and post g-tube insertion, significant only for MAMC at 12 months (p = 0.037) post g-tube insertion. In older children little change occurred during CPD, with all variables increasing post g-tube insertion, significant only for MAMC at 6 months (p = 0.02) and 12 months (p = 0.02). An increase in total protein and albumin was noted; however, no significant changes in any biochemical parameters were observed. CONCLUSIONS: Supplemental g-tube feeding facilitates weight gain in infants and older children receiving CPD and arrests the decline in height SDS traditionally observed in infants with end-stage renal disease. No significant alteration was observed in measured biochemical variables, although an increase in total protein and albumin was noted.

Hemodialysis for end-stage renal disease in children weighing less than 10 kg.

Hemodialysis (HD) of infants with end-stage renal disease (ESRD) is technically difficult and labor intensive, although there are few data in the literature to document the outcomes of this treatment. We retrospectively reviewed all patients with ESRD who received HD between 1983 and 1997 who weighed <10 kg at the beginning of HD. A total of ten patients aged 2-27 months, weighing 3.5-9.5 kg, were identified. All patients were dialyzed through a central venous line; three had a failed sapheno-femoral loop and one a failed brachial shunt. Line clot was observed in nine and line sepsis in six patients. Subclavian vein stenosis was documented in one patient following removal of a clotted subclavian line. The mean urea reduction ratios calculated during the 1st and 3rd month of HD were only 54% and 49%, respectively. Anemia was a frequent problem, despite the use of erythropoietin in seven of the infants. Outcomes included: successful renal transplant in four, switch back to peritoneal dialysis in two, improved renal function and dialysis discontinuation in one, and death after withdrawal of treatment in three patients. All three patients who died were <5 months of age, weighed <5 kg, and were anuric; two of the three had congenital nephrotic syndrome. In conclusion, successful HD is possible in small children with ESRD, but morbidity is substantial and mortality is high.

Complications of gastrostomy feeding in children receiving peritoneal dialysis.

Gastrostomy tube (g-tube) feeding is recognized to improve the nutritional delivery to children with end-stage renal disease. A retrospective study was undertaken assessing the complications of g-tube feeding in children receiving peritoneal dialysis (PD). Twenty-three patients, mean age 3.8+/-3.2 years received PD and g-tube feeding for 758 patient-months, with 127 patients receiving PD for 1,969 patient-months used as controls. Peritonitis occurred every 18.4 patient-months in controls and 7.8 patient-months in those with a g-tube. Peritonitis occurred every 6.0 patient-months before and 8.1 patient-months after g-tube insertion in those undergoing g-tube insertion on PD. PD catheter exit site infection (PDESI) occurred every 18.7 patient-months in controls and 16.8 patient-months in those with a g-tube. PDESI occurred every 126 patient-months before and 16.2 patient-months following g-tube insertion. PD catheter replacement secondary to infection occurred every 109.4 patient-months in controls and 39.9 patient-months in those with a g-tube. It did not occur before g-tube insertion and occurred every 32.5 patient-months following insertion. Thirty-four episodes of g-tube exit site infection occurred, in 10 the same organism caused concurrent peritonitis. G-tube replacement occurred on 37 occasions. Hemodynamically significant gastrointestinal bleeding occurred in 3 patients, being terminal in 1. We conclude that, although not without risk, g-tube feeding in patients receiving PD is not contraindicated.

Attitudes of pediatric nephrologists to management of end-stage renal disease in infants.

A multinational survey of pediatric nephrologists found no intercountry difference in the rate at which renal replacement therapy is offered to infants with end-stage renal disease. Overall, renal replacement therapy is offered by 41% to all infants < 1 month old and by 53% to all infants between 1 and 12 months.

Extrauterine twin-twin transfusion affects renal function and perioperative management of conjoined twins.

This series describes the occurrence of unbalanced circulatory shunting in three consecutively treated pairs of conjoined twins. The impact of renal functional changes and compensatory cardiac physiology on the timing of surgery and perioperative management are illustrated. The craniopagus set of twins presented in renal failure (1A) and cardiac failure (1B) to our hospital at age 2.5 years. Renal transplantation for anuria was performed in 1A before separation of the twins. This did not improve urine output in the hypoperfused twin, and normal renal function was not restored until the twins were separated. Two sets of omphalopagus twins were delivered and transferred to our hospital and separated during the first week of life. In each case a preoperative oliguric state in the underperfused twin reversed after separation, and a postoliguric diuresis ensued. Serum creatinine levels were similar in each pair preoperatively despite the inequality in urine volumes. In conjoined twins, assessment of renal function is necessary and should include serial measurements of urine volumes and urine creatinine clearance. Serum creatinine is not a useful marker of individual twin renal function in this situation. When disparity in renal function exists, early separation is indicated to prevent renal failure and compensatory cardiac failure.

An economic evaluation of hospital-based hemodialysis and home-based peritoneal dialysis for pediatric patients.

The purpose of this study was to assess the relative health system cost of pediatric ambulatory hospital-based hemodialysis and home-based peritoneal dialysis, including both continuous ambulatory peritoneal dialysis and continuous cycling peritoneal dialysis when either treatment is equally appropriate. A cost analysis was performed from the viewpoint of the "study hospital" and service providers (physicians) using treatment protocols, based on current clinical practice, which incorporate procedures to establish dialysis access sites, ongoing dialysis maintenance, and possible complications. Cost estimates used information from the period between April 1, 1993, to March 31, 1994, including fully allocated inpatient and outpatient costs. A sensitivity analysis was conducted to analyze the effect of complications on treatment costs. Total annual costs (in 1994 Canadian dollars, $1.00 CDN approximately $0.75. US) of a typical and uncomplicated continuous ambulatory peritoneal dialysis, continuous cycling peritoneal dialysis, and hemodialysis patient were $47,569, $48,658, and $76,023, respectively. Differences in cost between peritoneal dialysis and hemodialysis patients were due to hemodialysis maintenance costs, which were attributed to larger physician fees (25.8 percent), greater direct treatment costs incurred by the study hospital (14.2 percent), and higher overhead costs (60.0 percent). The expected total cost of hemodialysis complicated by an arteriovenous fistula clot and central venous line blockages, or peritoneal dialysis complicated by hernia repair and peritonitis was $78,568 and $50,438 for hemodialysis and peritoneal dialysis, respectively. For the range of complication probabilities considered, expected total costs were always lower with peritoneal dialysis than with hemodialysis. The cost analysis demonstrates that peritoneal dialysis is less costly than hemodialysis for pediatric patients. Such analyses are but one component of the treatment decision, and as such, should not be viewed as the sole means to yield a treatment decision, but rather as a device for systematically evaluating the alternative treatment options.

Renal biopsy in children: comparison of two techniques.

Two hundred and thirty-five children who underwent percutaneous renal biopsy under real-time ultrasound guidance at The Hospital for Sick Children, between 1 January 1991 and 31 March 1993, were studied to compare the incidence of complications after biopsies with the Trucut needle (TN) and the Bard Biopty gun (BG). Of the 190 cases for which full clinical details were available and in which a single instrument was used for renal biopsy, 157 were biopsied with the BG and 33 with the TN. There was no significant difference between the two groups in variables such as age, weight, sex, number of needle passes and number of tissue cores obtained. The proportion of native and allograft biopsies in each group was similar. More children in the TN group underwent biopsy under general anaesthesia. Adequate diagnostic tissue samples were obtained in 189 of 190 cases. There were more complications in the TN group than in the BG group (P < 0.001). When allograft and native kidney biopsies were analysed separately, this difference in complications remained highly significant for the native kidney group (P < 0.005), though not for the allograft group. When the effect of needle size alone was investigated, there was no significant difference in the incidence of complications when TN biopsies were compared with 14-gauge BG biopsies or when 14- and 18-gauge BG biopsies were compared with each other.

Mass transfer area coefficients in children.

OBJECTIVE: Measurement of mass transfer area coefficients (MTAC) in children of different sizes to determine if solute transport varies with age and to compare with published adult values. DESIGN: Mass transfer area coefficients calculated from prospectively collected data in 28 selected patients. PARTICIPANTS: All children starting maintenance peritoneal dialysis at the Hospital for Sick Children. Selected patients were also studied if hospitalized for unrelated reasons. RESULTS: Mean MTAC values for creatinine and glucose were 4.0 and 4.5 mL/min, respectively, both considerably lower than adult values. When scaled per 70 kg body weight, these results were greater, and when scaled per 1.73 m2 surface area, they were lower than reported adult values. The MTAC/kg body weight was inversely correlated to age. CONCLUSIONS: Solute transport in children is directly related to age and does not approach adult values until later childhood. However, more rapid transport per unit body weight is observed in children and may reflect an increased effective peritoneal surface area.

Respiratory function in the prune-belly syndrome.

Respiratory function was evaluated in 11 patients with prune-belly syndrome. Nine had evidence of gas trapping and six of restrictive lung disease. These abnormalities of lung function appear to be secondary to the musculoskeletal disorder associated with prune-belly syndrome rather than parenchymal lung disease.