Thromboprophylaxis in congenital nephrotic syndrome: 15-year experience from a national cohort

INTRODUCTION

Congenital nephrotic syndrome (CNS) is an ultra-rare disease associated with a pro-thrombotic state and venous thromboembolisms (VTE). There is very limited evidence evaluating thromboprophylaxis in patients with CNS. This study aimed to determine the doses and duration of treatment required to achieve adequate thromboprophylaxis in patients with CNS.

METHODS

From 2005 to 2018 children in Scotland with a confirmed genetic or histological diagnosis of CNS were included if commenced on thromboprophylaxis. The primary study endpoint was stable drug monitoring. Secondary outcomes included VTE or significant haemorrhage.

RESULTS

Eight patients were included; all initially were commenced on low-molecular weight heparin (enoxaparin). Four patients maintained therapeutic anti-Factor Xa levels (time 3-26 weeks, dose 3.2-5.07 mg/kg/day), and one patient developed a thrombosis (Anti-Factor Xa: 0.27 IU/ml). Four patients were subsequently treated with warfarin. Two patients maintained therapeutic INRs (time 6-11 weeks, dose 0.22-0.25 mg/kg/day), and one patient had two bleeding events (Bleed 1: INR 6, Bleed 2: INR 5.5).

CONCLUSIONS

Achieving thromboprophylaxis in CNS is challenging. Similar numbers of patients achieved stable anticoagulation on warfarin and enoxaparin. Enoxaparin dosing was nearly double the recommended starting doses for secondary thromboprophylaxis. Bleeding events were all associated with supra-therapeutic anticoagulation.

Early Continuous Cycling Peritoneal Dialysis Failure in Infants: Rescue Tidal Peritoneal Dialysis

Failure of peritoneal dialysis (PD) immediately following soft catheter insertion is well recognized and may be manifest by dialysate leakage, early peritonitis, or early inadequate outflow (1,2), the latter of which requires catheter replacement in up to 50% of cases (1). We describe 3 infants with failure of continuous cyclic peritoneal dialysis CCPD) following PD catheter insertion, as a result of poor dialysate outflow. In each case adequate dialysis was achieved using tidal PD.

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 (≤ 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.

Bilateral ureteric obstruction secondary to renal papillary necrosis

A 2-year-old male presented to hospital with a 5-day history of vomiting and pyrexia. He was initially treated with non-steroidal medication as an anti-pyretic. Initial investigations demonstrated a raised urea and creatinine and he was treated with intravenous fluids. Within 24 h he became anuric with progressive renal insufficiency. Ultrasound scan demonstrated minimal bilateral hydronephrosis with debris in the lower pole calyces. The bladder was empty. Cystoscopy and retrograde contrast imaging revealed bilateral ureteric obstruction. Double J stents were inserted and his renal function returned to normal within 4 days. We believe the aetiology to be renal papillary necrosis and bilateral ureteric obstruction secondary to the administration of ibuprofen in association with dehydration.

Reversible chronic pulmonary fibrosis associated with MMF in a pediatric patient: a case report

We describe a case of chronic mineralizing pulmonary elastosis in a seven-yr-old boy following DD renal transplantation for Wilms tumour. Fourteen months post-transplantation he developed respiratory symptoms with lung biopsy demonstrating chronic mineralizing pulmonary elastosis thought to be secondary to immunosuppression with MMF. Symptomatic resolution occurred following MMF cessation.

Body composition and nutritional intake in children with chronic kidney disease

The aim of this study was to assess body composition in children with chronic renal failure (CRF) and post renal transplantation (Tx), and to compare it to body mass index (BMI) and nutritional intake. Dietary assessment using 3-day diaries, total and regional body composition assessment by dual x-ray energy absorptiometry of 50 CRF children (29M, 21F), median age 8.9 yrs and 50 Tx children (32M, 18F), median age 12.9 yrs. BMI, percentage fat mass (%FM) and lean mass (LM) were corrected for height and expressed as SDS (HSDS). In both groups, BMIHSDS was lower than %FMHSDS and higher than LMHSDS (p<0.05). In the Tx group, there were associations on bivariate analysis between energy & protein intake and BMIHSDS & %FMHSDS (r,0.5, p<0.05), and between LMHSDS and protein intake (r,0.5, p<0.05). On multivariate analysis, there was an association between LMHSDS and time since transplantation (r,-0.4, p<0.05). Children in the CRF and Tx groups had a high percentage predicted trunk:leg FM ratio of 148% and 157%, respectively. Children with CRF and Tx have discordant body composition with a relatively high FM and low LM, which is not reflected by BMI. In addition, they appear to have an increased level of central adiposity that may predispose them to increased morbidity in later life.

Renal transplant biopsy specimen adequacy in a paediatric population

Updated guidelines on the diagnosis of acute allograft rejection including criteria for biopsy specimen adequacy were published in 1999. We sought to determine the adequacy of specimens in paediatric transplant patients and identify factors influencing adequacy. All renal transplant biopsies performed between 1998 and 2003 were classified as adequate (n =25), minimal (n =19) or inadequate (n =27) in accordance with the Banff 97 criteria, and the histological diagnoses were documented. The effect on specimen adequacy of grade of operator, method of sedation, age of child, needle gauge, number of cores and total core length was then investigated. Overall, a minimal or adequate specimen was obtained in 62% of cases. No histological diagnosis could be made in 30% of all specimens, just over half of which were inadequate. Higher rates of rejection were found in adequate (52%) than inadequate (33%) samples. The grade of operator (p =0.498), the age of the child at the time of biopsy (p =0.815) and type of sedation (p =0.188) did not affect adequacy. More than one core was obtained in 38 (54%) cases, and this was significantly associated with specimen adequacy (p <0.0005) as was longer total core length (p =0.002). Clinical features in isolation are not sufficient for the diagnosis of acute allograft rejection. Renal biopsy remains the gold standard and relies on adequate specimen collection. Our data shows that specimen adequacy according to the Banff 97 guidelines is achievable in children and that more than one core at the time of sampling significantly improves this achievement. Adequate sampling reduces the risk of an inconclusive histological diagnosis.

Bone mineral content, corrected for height or bone area, measured by DXA is not reduced in children with chronic renal disease or in hypoparathyroidism

The combination of poor growth and parathyroid and mineral disorders complicates the diagnosis of renal bone disease in children with chronic renal insufficiency (CRI), and the role of dual X-ray absorptiometry (DXA) is unclear. We aimed to examine the role of DXA in assessing variation in size-adjusted bone mineral content (BMC) in children with CRI and compare it with a cohort with hypoparathyroidism (HPT) and pseudo-hypoparathyroidism (PHPIa). In 29 patients with CRI (21 male) with a median age of 11 years (10th, 90th centiles 4.4, 14.6) and 10 patients with HPT and PHPIa (three male), with a median age of 13.7 years (7, 16) lumbar spine (LS) and total body (TB) BMC were measured by DXA. Age-, gender- and height-matched data allowed calculation of percentage predicted bone area for age and gender (pBAr) and percentage predicted BMC for bone area and height. In the CRI group, the median glomerular filtration rate (GFR) was 27.4 ml/min per 1.73 m2 (7.1, 69.5), and the median duration of illness was 9.3 years (2.1, 12.1). Median height standard deviation score (Ht SDS) was -1.6 (-3.0, 0.3), and, as expected, median LS and TB pBAr were low at 82% (68, 974) and 76% (63, 92), respectively. LS and TB predicted BMC (pBMC) SDS (corrected for bone size) were generally high, with a median value of 0.4 (-0.9, 1.4) and 0.4 (-0.1,0.9), respectively. Analysis of the prepubertal subset of children (n=15) showed that median percentage predicted LS BMC for height was 104% (80, 116), whereas the median TB BMC for height was 96% (74, 108). Median Ht SDS of the HPT and PHPIa cohort was -0.3 (-2.9, 0.3) and median LS and TB pBAr were 90% (66, 100) and 91% (76, 98), respectively. Median LS and TB pBMC SDS were 0.6 (-0.4, 1.8) and 0.7 (0.3, 1.1), respectively. Median percentage predicted LS and TB BMC for height were 102% (82, 114) and 102% (92, 122). There was no relationship between pBMC SDS and duration of illness, GFR, vitamin D dose, serum intact parathyroid hormone (PTH), serum calcium/phosphate product or serum total alkaline phosphatase (ALP) in the CRI or the HPT cohort. However, one of the highest pBMC SDSs was recorded in a child with PHPIa before she started on any treatment. In children with CRI, BMC, when adjusted for co-existing growth retardation, is similar to that observed in children with hypoparathyroidism. The correct reading of BMC needs a correction for bone size.

Vascular access survival in children and young adults receiving long-term hemodialysis

BACKGROUND

The delivery of long-term hemodialysis therapy in children is complicated by smaller vascular caliber and the potential lifelong requirement for hemodialysis access. Various factors have resulted in the increased use of cuffed central venous catheters (CVLs) in preference to autologous arteriovenous fistulae (AVFs) and arteriovenous synthetic grafts (AVGs). The aim of this study is to compare CVL, AVF, and AVG survival and determine factors affecting their survival.

METHODS

A 20-year retrospective study was undertaken of pediatric patients receiving long-term hemodialysis therapy. Age, height, weight, body mass index, and sex were noted at each procedure, in addition to the presence of hypoalbuminemia, underlying diagnosis, type and site of vascular access, and effect of previous access surgery. The grade of operator also was noted.

RESULTS

Three hundred four vascular access procedures were performed on 114 patients, with a median age at initial access formation of 12.0 years (range, 4 weeks to 21.9 years). The most common procedure was CVL insertion (182 procedures) and then AVF formation (107 procedures), with only 15 AVGs created. Median censored survival was 3.14 years (95% confidence interval, 1.22 to 5.06) for AVFs and 0.6 years (95% confidence interval, 0.20 to 1.00) for CVLs. Factors adversely affecting vascular access survival were younger age, trainee operator, presence of hypoalbuminemia, and type of access undertaken, with AVF better than CVL.

CONCLUSION

This study shows increased survival of AVFs over CVLs and AVGs. Vascular access in children and adolescents may impact on future dialysis accessibility and should be undertaken by those most experienced in each technique.

Skeletal Disproportion in Children with Chronic Renal Disease

OBJECTIVES

To assess stature and skeletal disproportion in children with chronic renal disease.

METHODS

Cross-sectional study of height (HT), sitting height (SH), subischial leg length (SILL), sitting height/height ratio (SH:HT) and disproportion score (SH SDS minus SILL SDS) in 56 children (M:35) with median age 11.4 years (range 4.5,18.7) with chronic renal disease.

RESULTS

There were 19 children with chronic renal insufficiency, 6 receiving peritoneal dialysis and 31 after renal transplant. The median HTSDS for the whole group was -1.21 (-2.8, 0.35). The median SH:HT ratio in non-transplanted children and renal transplant were 0.51 (0.49, 0.53) and 0.50 (0.48, 0.53), respectively (p = 0.02). The median disproportion score of the whole group was -3.2 (-4.8, -1.8). There was a significant correlation between disproportion score and SH:HT (r = 0.5, p = 0.005). SH:HT ratio was negatively related to duration of illness (r = 0.4, p = 0.005).

CONCLUSION

Children with chronic renal disease have significant body disproportion and this may be due to a disproportionately greater effect of disease and treatment on spinal growth.

Glomerular basement membrane thickness in children: a stereologic assessment

BACKGROUND

Stereologic methods have emerged as the technique of choice in assessing glomerular basement membrane (GBM) thickness, following conceptual modeling comparing the stereologic technique of harmonic mean of the orthogonal intercept estimation (Th) with the model based method of arithmetic mean estimation (ATH), with no direct comparison undertaken. We undertook to establish the gold standard for GBM estimation and use this technique to establish a range for GBM thickness in children.

METHODS

Intra-observer and inter-glomerular variation was estimated in 34 cases with (presumed) normal GBM thickness, using Th, ATH and a rapid direct measurement technique, with intra-observer variation measured in 35 cases with GBM attenuation. A total of 34,011 measurements were undertaken to establish a range for Th in children on 212 biopsies from 199 patients (127 male) demonstrating minimal change nephropathy (N = 153), focal segmental glomerulosclerosis (24), no abnormality (24), and acute tubular necrosis (8), which were used as surrogates for normals.

RESULTS

Th demonstrated less variation than ATH in both the normal and attenuated groups. GBM thickness increased throughout childhood, from 194 +/- 6.5 nm (mean +/- SE) at one year to 297 +/- 6.0 nm at 11 years, with a reduced rate of increase after age 11 years.

CONCLUSION

Stereologic methods are superior to model based techniques in estimating GBM thickness and should be regarded as the technique of choice in this area. GBM thickness was observed to increase during childhood with no gender effect demonstrable as a main effect or interaction.

Hypercalcaemia in association with trisomy 21 (Down's syndrome)

The combination of hypercalcaemia, hypercalciuria, and nephrocalcinosis with and without renal impairment is rare in paediatric clinical practice. However, this constellation of findings has been reported in three children with trisomy 21, but the absence of detailed nutritional data has failed to clarify the underlying pathogenesis. This report describes a 4 year old girl with trisomy 21 who was found coincidentally to have hypercalcaemia, hypercalciuria, nephrocalcinosis, and renal impairment in the absence of metabolic alkalosis, following a prolonged period of excessive calcium intake.

Vesicoureteric reflux associated with renal dysplasia in the Wolf-Hirschhorn syndrome

Wolf-Hirschhorn syndrome (WHS) is caused by a partial deletion of the short arm of chromosome 4 (4p16.3) and is characterized by severe pre- and postnatal growth retardation, developmental delay, and multiple congenital anomalies, including malformations of the urogenital system. We describe the renal and urinary tract phenotype in a series of six children with WHS. Vesicoureteric reflux was present in four of our six patients (5 of 10 ureters), an abnormality not previously reported in WHS.

Accuracy of clean-catch urine collection in infancy

OBJECTIVE

To compare the accuracy of cultures of urine obtained by clean-catch urine (CCU) collection and suprapubic aspiration (SPA) in infants.

DESIGN

Prospective case series undertaken in a pediatric teaching hospital and associated neonatal unit. Fifty-eight paired urine cultures (CCU collection and SPA) were obtained from 49 infants with suspected urinary tract infection. The primary outcome measure was the presence or absence of significant bacteriuria on both CCU collection and SPA; secondary outcome measures were the success of SPA with ultrasound guidance compared with aspiration without ultrasound guidance. Statistical analysis was done by using a chi(2) test.

RESULTS

A false-positive rate of 5% and a false-negative rate of 12% were recorded. Sensitivity was 88.9% (95% CI 65.3-98.6), and specificity was 95.0% (95 CI% 83.1-99. 4). Ultrasound-assisted SPA was successful in 26 of 28 patients (93%) and in 13 of 21 patients (62%) when SPA was performed without ultrasound (chi(2) = 7.08, P =.008).

CONCLUSIONS

We conclude that there is a good association in results of culture of urine obtained by CCU collection and SPA and would encourage the use of the CCU technique.

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.

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.

Hypophosphatasia

Hypophosphatasia is a rare inherited metabolic disease characterised by reduced plasma and tissue alkaline phosphatase activity, and may present in infancy, childhood or adulthood. The differing modes of inheritance, presentation and natural history are likely to reflect variable expression of the alkaline phosphatase gene defect. A case of infantile hypophophatasia presenting with hypercalcaemia is described and the histological and radiological resolution of the mineralisation defect present initially are reported.

Hypomagnesaemic tetany

Hypomagnesaemic tetany (hypomagnesaemic tetany with secondary hypocalcaemia) is a rare inherited form of hypomagnesaemia. Initial reports involved affected males only; however, affected females have also been reported. The case of a child with hypomagnesaemic tetany is described, the biochemical and genetic aspects of this condition are reviewed and the importance of the assessment of renal magnesium excretion in patients presenting with hypomagnesaemia is highlighted.

An audit of the clinical management of urinary tract infection in childhood

Urinary tract infection (UTI), is one of the commonest bacterial diseases in childhood, and may cause significant morbidity, inconvenience and anxiety for patients and their families and result in considerable consumption of resources. Although most clinicians would agree on the general principles of management, it is recognised that considerable variation exists in their application. The aim of this study was to assess the in-patient and out-patient management practice in infants and children with documented symptomatic UTI in several clinical areas in the Royal Hospital for Sick Children (RHSC) Glasgow. A total of 1,826 patient episodes were analysed, 1,592 of which were first referrals over a 29 month study period. The analysis highlighted a definite variation in a number of aspects of the management of UTI within the clinical services reviewed. In a significant number of in-patients, the diagnosis was made both in the absence of microbiological confirmation, and following the use of inappropriate urine specimens. An under-use of urine microscopy in the in-patient services was documented as well as an inappropriate use in out-patients, since the result in this latter group did not seem to influence the need for urine culture. Urinary tract imaging protocols varied widely between in-patient services and among in-patient and out-patient services with a continued over-reliance on urinary tract ultrasound and an under-use of more sensitive radio-isotopic techniques. These data reveal a continuing lack of uniformity in management practices in children with UTI and demonstrate the need for a wider application of practice guidelines.