Ambulatory blood pressure monitoring after renal transplantation in children

Hypertension occurs commonly following renal transplantation and may cause end organ damage, such as cardiac hypertrophy. This study seeks to determine which features of hypertension are related to cardiac hypertrophy in children after renal transplantation. Ambulatory blood pressure monitoring (ABPM) was performed in 45 pediatric patients, 4.9+/-3.0 years after renal transplantation. ABPM data were related to clinical features and echocardiographic measurements. Hypertension was demonstrated in 33% of patients by casual blood pressure (BP) measurement and in 40% by ABPM. The mean percentage nighttime decline in BP (dipping) was 8.9+/-5.0% for systolic and 13.9+/-7.7% for diastolic BP. Abnormal dipping (<10%) was seen in 58% of patients. BP load (percentage of BP recordings above 95th percentile) was >30% in 44% of patients. Patients taking antihypertensive medication had more abnormal dipping and greater nighttime BP load. The prevalence of left ventricular hypertrophy was 72% before transplantation, 75% after transplantation, and 54% near to ABPM. Left ventricular mass (LVM) indexed to height(3) decreased significantly after transplantation. (40.2+/-14.7 vs. 35.0+/-8.3 g/m(3), P=0.0002). There was no significant relationship between ABPM data and LVM. ABPM was not able to differentiate those patients with persistently elevated LVM. The results suggest that hypertension is not always associated with cardiac hypertrophy following pediatric renal transplantation.

Children with hypoalbuminemia on continuous peritoneal dialysis are at risk for technique failure

BACKGROUND

Few data are available on the clinical significance of hypoalbuminemia [serum albumin (SA) <35 g/L] in children with end-stage renal disease (ESRD) on continuous peritoneal dialysis (CPD). This study was conducted to analyze the prevalence of hypoalbuminemia, its predictive factors, and its clinical impact in these children.

METHODS

A retrospective analysis was done of 180 patients on CPD over the last 22 years. Patients were excluded from the study if they were on CPD for less than four months or had nephrotic syndrome. Demographic, clinical, and biochemical variables were studied. Children continued on CPD until they received a transplant or were transferred to an adult unit or to hemodialysis as a result of technique failure. The subjects were divided into two groups based on SA levels at last follow-up.

RESULTS

A total of 135 children was included. After a mean duration of CPD of 573 +/- 437 (120 to 2960) days, 54 children (40%) were observed to have hypoalbuminemia. Four patients (2.9%) died, 7 (5.2%) continued on continuous cyclic peritoneal dialysis, and 13 (9.6%) were transferred to an adult unit for continuation of CPD. Ninety-five (70.3%) were transplanted, and 16 (11.8%) were transferred to hemodialysis because of technique failure. Children in group I (N = 54, SA <35 g/L), compared with group II (N = 81, SA > or =35 g/L), were younger at initiation of PD, more likely to have hypoalbuminemia at one month and six months after initiation of PD, and have more episodes of peritonitis. No differences were seen between the groups in gender, modality of CPD, body surface area, initial body mass index, and presence of hypertension or acidosis. The only factors predictive of hypoalbuminemia on follow-up were low SA at one month after PD and recurrent peritonitis using multiple logistic regression analysis. Evaluating the clinical impact of hypoalbuminemia, we observed a higher incidence of failed PD in children who had hypoalbuminemia.

CONCLUSION

Low SA at one month after PD and recurrent peritonitis are predictive of hypoalbuminemia in children on CPD, which is associated with an increased incidence of CPD failure.

Ultrasound biomicroscopy of the eye in cystinosis

OBJECTIVE

To describe the ocular ultrasound biomicroscopy (UBM) findings in patients with cystinosis.

METHODS

Six patients with infantile nephropathic cystinosis, aged 16 to 25 years, and 6 controls (matched for age and spherical refractive error) were examined clinically and with UBM. Scleral reflectivity, corneal and iris thickness, central anterior chamber depth, angle width, trabecular meshwork to ciliary process distance, and ciliary sulcus width were measured.

RESULTS

No patient had glaucoma or posterior synechiae, but all had crystals in the trabecular meshwork apparent with gonioscopy. Using UBM, the cornea and iris appeared similar in both groups, but the scleral reflectivity was increased in patients (P =.003). The angle was narrower in patients (mean +/- SD, 20 degrees +/- 7 degrees ) than controls (31 degrees +/- 5 degrees, P<. 001). The anterior chamber was shallower in patients (2556 +/- 197 microm) than controls (2968 +/- 284 microm, P<.001). The ciliary sulcus was closed or narrow in all patients (83 +/- 112 microm) compared with controls (339 +/- 135 microm, P<.001), with a reduction in the trabecular meshwork to ciliary process distance.

CONCLUSIONS

This report of ocular UBM findings in cystinosis demonstrated narrowing of the angle and a ciliary body configuration similar to that reported for plateau iris syndrome. Gonioscopy demonstrated crystals in the trabecular meshwork. These findings may explain the predisposition of these patients to glaucoma.

Ambulatory blood pressure monitoring in children: a large center's experience

Ambulatory blood pressure monitoring (ABPM) is well established in adults and is becoming common in children. We reviewed 190 ABPM studies retrospectively (since 1990) to assess the failure rate, and analyzed the data from 97 patients 5-19 years old (1992-1996) to review the experience gained from the use of this technique in children and adolescents. Seventeen percent (32/190) of studies failed. Most children accepted ABPM, provided it was clearly explained in advance. There were differences between day and night readings of systolic blood pressure (BP), diastolic BP, and heart rate. BP did not correlate with height or weight. "White coat" effect apparently exists in children: clinic systolic BPs were higher than daytime systolic ABPM (no difference in diastolic). Eighty-nine percent (86/97) had an elevated BP load (>30% of readings >95th percentile). The antihypertensive medications of 16% (16/97) of patients were changed after ABPM. The nocturnal fall in BP (expressed as a percentage of the individual mean daytime values) was approximately normally distributed and was independent of age and height. Nocturnal systolic and diastolic dipping were closely correlated. Attenuation of nighttime dipping was observed in children with kidney disease and those with organ transplants. There is a need for normative data for ABPM for North American children. In our study, the technique was useful in selected cases, such as borderline or secondary hypertension, and for therapeutic monitoring when BP control is difficult.

Nosocomial transmission of tuberculosis (TB) associated with care of an infant with peritoneal TB

Nosocomial transmission of tuberculosis (TB) after exposure to infected peritoneal fluid has not been described. We report the exposure of 111 healthcare workers to infected dialysate from an infant with TB peritonitis. Two (5%) of 39 primary-care nurses, but no doctors or environmental service workers, had apparent tuberculin skin test conversions, raising the concern that patients with peritoneal TB may be a source for nosocomial transmission of TB.

Effects of amino acid dialysis compared to dextrose dialysis in children on continuous cycling peritoneal dialysis

OBJECTIVE

To compare the biochemical and nutritional effects of amino acid dialysis with dextrose dialysis in children receiving continuous cycling peritoneal dialysis (CCPD).

DESIGN

A prospective randomized cross-over study.

SETTING

Nonhospitalized patients.

PATIENTS

Seven children aged 1.8 to 16.0 years (mean 8.1 years) with end-stage renal disease who were receiving CCPD.

INTERVENTIONS

Each patient received nighttime automated CCPD of dextrose, plus a single daytime dwell of either amino acid dialysate or dextrose dialysate. After 3 months, subjects crossed over to the alternative regimen for a subsequent 3 months.

MAIN OUTCOME MEASURES

Creatinine clearance, ultrafiltration, urea, creatinine, electrolytes, total protein, albumin, fasting plasma amino acids, anthropometrics, total body nitrogen.

RESULTS

Amino acid dialysis was comparable to dextrose dialysis for creatinine clearance and ultrafiltration. Plasma urea concentrations were higher during amino acid dialysis. No clinical side effects or worsening of metabolic acidosis was observed. Caloric intake increased and protein intake improved. Appetite and total body nitrogen increased in at least half the children during amino acid dialysis. Total plasma protein and albumin concentrations did not change significantly. Fasting plasma concentrations of amino acids after 3 months of amino acid dialysis were comparable to baseline values. For several amino acids, the dose-response curve was blunted after a single amino acid exchange following 3 months of amino acid dialysis, which may, in part, be due to the induction of hepatic enzyme synthesis.

CONCLUSIONS

Amino acid dialysis is an efficient form of peritoneal dialysis that should be considered for children with poor nutritional status for whom enteral nutrition supplementation has been unsuccessful. Further study is needed to determine the optimal amount of amino acids to deliver, the best time to administer the amino acid dialysis fluid, and the benefits of adding dextrose to the amino acid solution.

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.

Cutaneous telangiectasias, sparse hair, and type I membranoproliferative glomerulonephritis

We report the unusual association of normocomplementemic type I membranoproliferative glomerulonephritis in a 10-year-old girl with sparse red hair, absent eyebrows and eyelashes, cutaneous telangiectasias, and an atrial septal defect.

Non-steroidal anti-inflammatory drug-associated nephrotoxicity in Bartter syndrome

We have followed four patients with Bartter syndrome for a mean of 25.4 years (range 21.5-28.8 years) after diagnosis. All patients received non-steroidal anti-inflammatory drugs (NSAID). In all patients, various degrees of renal dysfunction were noted to be temporally associated with NSAID therapy. In two patients, renal dysfunction resolved after discontinuing NSAID therapy, while maintaining other chronic medications such as potassium-sparing diuretics. Renal dysfunction persisted after NSAID withdrawal in two patients. We report these cases as a warning that NSAID should be considered an important cause of either reversible or irreversible renal dysfunction in Bartter syndrome.

Examination of genotype and phenotype relationships in 14 patients with apparent mineralocorticoid excess

Apparent mineralocorticoid excess (AME) is a genetic disorder causing pre- and postnatal growth failure, juvenile hypertension, hypokalemic metabolic alkalosis, and hyporeninemic hypoaldosteronism due to a deficiency of 11 beta-hydroxysteroid dehydrogenase type 2 enzyme activity (11 beta HSD2). The 11 beta HSD2 enzyme is responsible for the conversion of cortisol to the inactive metabolite cortisone and therefore protects the mineralocorticoid receptors from cortisol intoxication. Several homozygous mutations are associated with this potentially fatal disease. We have examined the phenotype, biochemical features, and genotype of 14 patients with AME. All of the patients had characteristic signs of a severe 11 beta HSD2 defect. Birth weights were significantly lower than those of their unaffected sibs. The patients were short, underweight, and hypertensive for age. Variable damage of one or more organs (kidneys, retina, heart, and central nervous system) was found in all of the patients except one. The follow-up studies of end-organ damage after 2-13 yr of treatment in six patients demonstrated significant improvement in all patients. The urinary metabolites of cortisol demonstrated an abnormal ratio with predominance of cortisol metabolites, i.e. tetrahydrocortisol plus 5 alpha-tetrahydrocortisol/tetrahydrocortisone was 6.7-33, whereas the normal ratio is 1.0. Infusion of [11-3H]cortisol resulted in little release of tritiated water, indicating the failure of the conversion of cortisol to cortisone. Thirteen mutations in the HSD11B2 gene have been previously published, and we report three new genetic mutations in two patients, one of whom was previously unreported. All of the patients had homozygous defects except one, who was a compound heterozygote. Our first case had one of the most severe mutations, resulting in the truncation of the enzyme 11 beta HSD2, and died at the age of 16 yr while receiving treatment. Three patients with identical homozygous mutations from different families had varying degrees of severity of clinical and biochemical features. Due to the small number of patients with identical mutations, it is difficult to correlate genotype with phenotype. In some cases, early and vigilant treatment of AME patients may prevent or improve the morbidity and mortality of end-organ damage such as renal or cardiovascular damage and retinopathy. The outcome of treatment in more patients may establish the efficacy of treatment.

Diagnosis and management of stenotic aorto-arteriopathy in childhood

Stenotic aorto-arteriopathy is an uncommon vascular lesion characterized by segmental arterial stenoses. We reviewed the experience with several management algorithms to define the most effective management course. The clinical records of 14 pediatric patients with acquired SAA who presented over a 16-year period were reviewed. Most patients presented with a mid-thoracoabdominal coarctation and were diagnosed with Takayasu arteritis. Differentiating between Takayasu arteritis and fibromuscular dysplasia was difficult on clinical grounds or by angiography. Medical management of the end-organ disease and renovascular hypertension was only palliative. Selective percutaneous transluminal balloon angioplasty of the stenotic renal arteries had only transient benefits; renal autotransplantation had slightly better success. Dilation of stenosed aortic segments with balloon-expandable endovascular stents and subsequent renal autotransplantation proved useful. Distinguishing SAA resulting from fibromuscular dysplasia caused by Takayasu arteritis in the chronic vaso-occlusive phase may be unnecessary for effective treatment. Therapy should focus on interventions to minimize the end-organ damage caused by the vaso-occlusive manifestations of the disorders.

Brachydactyly-short stature-hypertension (Bilginturan) syndrome: report on two families

We report on two families with autosomal dominant brachydactyly of hands and feet and hypertension. All affected members of the first family had proportionate short stature. However, the propositus and the affected relatives in the second family were only short compared to unaffected relatives. The hypertension was medically responsive in all cases. The propositus in the second family had poor compliance and a striking generalized vasculopathy. All patients were of normal intelligence and had a normal facial appearance. The brachydactyly-short stature-hypertension syndrome was first reported by Bilginturan et al. [1973] in a Turkish family and the families reported by us are Caucasian and Hispanic. The gene causing this condition in the original Turkish family was recently mapped to 12p. Our report expands our existing knowledge and the ethnic diversity of this syndrome.

Renal tubular acidosis and osteopetrosis with carbonic anhydrase II deficiency: pathogenesis of impaired acidification

Renal tubular acidosis with osteopetrosis is an autosomal recessive disorder due to deficiency of carbonic anhydrase II (CAII). A 3.5-year-old Egyptian boy with osteopetrosis and cerebral calcification has a persistent normal anion gap type of metabolic acidosis (plasma pH 7.26) and a mild degree of hypokalemia. A baseline urine pH was 7.0; ammonium (NH4+) excretion was low at 11 mumol/min per 1.73 m2; fractional excretion of bicarbonate HCO3 (FEHCO3) was high at 9% when plasma HCO3 was 20 mmol/l; citrate excretion rate was high for the degree of acidosis at 0.35 mmol/mmol creatinine. Intravenous administration of sodium bicarbonate led to a urine pH of 7.6, a FEHCO3 of 14%, a urine-blood PCO2 difference of 7 mmHg, NH4+ excretion fell to close to nil, and citrate excretion remained at 0.38 mmol/mmol creatinine. Intravenous administration of arginine hydrochloride caused the urine pH to fall to 5.8, the FEHCO3 to fall to 0, the NH4+ excretion rate to rise to 43 mumol/min per 1.73 m2, and citrate excretion to fall to < 0.01 mmol/mmol creatinine. These results show that our patient had a low rate of NH4+ excretion, a low urine minus blood PCO2 difference in alkaline urine, and a low urinary citrate excretion, but only when he was severely acidotic. He failed to achieve a maximally low urine pH. These findings indicate that his renal acidification mechanisms were impaired in both the proximal and distal tubule, the result of his CAII deficiency.

Continuous peritoneal dialysis in children: past, present and future

Continuous peritoneal dialysis (CPD) in children has been an important mode of renal replacement therapy (RRT) since 1978. Continuous ambulatory peritoneal dialysis (CAPD) was used initially in children and then, in infants. Automated peritoneal dialysis (APD) was introduced in the eighties. Currently. CPD is the predominant mode of RRT in children, and 3/4 of these patients are managed with APD. Certain events have evolved with time, such as: a) growth and nutrition; b) renal osteodystrophy; c) anemia; and d) training. Complications from CPD continue to be a challenge and include: a) peritonitis; b) hernias and c) stress. Future directions in pediatric CAPD are: a) applying techniques to measure dialysis adequacy; b) improvement in dialysis solutions, such as pH, osmolality and different osmotic agents; c) additives to the dialysis fluid, such as hormones, growth factors; d) improvements in catheters and cyclers; and e) strategies to reduce peritonitis rates. There are challenges for CPD in the future; however, it appears to be the most practical and cost-effective dialysis therapy for children with end-stage renal disease.

A new classification for renal defects in net acid excretion

The traditional classification of the group of disorders called renal tubular acidosis (RTA) into proximal and distal subclasses is based on which nephron segment is thought to have an abnormal function. Nevertheless, such a distinction may not be correct and also does not characterize the pathophysiology of the renal acidosis in each patient. In this article, we propose an alternative classification, one that is based on the component of net acid excretion that is abnormal. We also suggest expanding the definition of net acid excretion to include a term that describes the renal handling of metabolizable organic anions because their loss in the urine represents the loss of "potential bicarbonate." Because a low rate of excretion of ammonium (NH4+) is present in patients with both distal and isolated proximal RTA, our initial clinical step in patients with hyperchloremic metabolic acidosis (HCMA) is to evaluate the rate of excretion of NH4+. The basis for a low rate of excretion of NH4+ is shown by examining the urine pH. If the urine pH is low, further studies are performed to determine why the availability of NH3 is low; if the urine pH is high, further investigations are initiated to examine if the defect in H+ secretion involves the proximal or the distal nephron. Conversely, if the rate of excretion of NH4+ is high in a patient with HCMA, a component of the degree of acidosis could be attributable to a high rate of excretion of metabolizable organic anions. Case examples are provided to illustrate the approach and its implications for future molecular studies.

Pediatric pheochromocytoma. A 36-year review

Fourteen children (10 boys and 4 girls, aged 8 to 17 years) had 20 pheochromocytomas treated over a 36-year period from 1959 to 1995 inclusive. Nine patients had 11 tumors before 1980; 5 children had 9 tumors up to 1987. There were no new children with pheochromocytomas at our hospital from 1988 to 1995. Hypertension, sweating, headache, and visual blurring were the most common symptoms and signs (average 5 months). The most reliable biochemical investigations were the urinary catecholamines and norepinephrine. Before 1980, intravenous pyelography and angiography were most successful in localizing the tumor, but since then ultrasonography and computerized tomography have been the radiological investigations of choice. Early involvement of the anesthesiologist in the preoperative control of the hypertension is essential; blood pressure (BP) control was achieved with phenoxybenzamine. The main anesthetic drugs used were: sodium thiopental, fentanyl, methoxyflurane, isoflurane, nitrous oxide, and metocurine. Sixteen tumors were adrenal and 4 were extra-adrenal (1 intrathoracic and 1 extradural). All except 2 tumors were completely resected; they ranged in size from 1.3 to 14 cm. Ligation of the tumor's venous drainage was usually associated with a sudden, temporary fall in systemic BP. There were 2 children with malignant tumors. Four patients had five recurrences (second pheochromocytoma) within 6 years, and all were heralded by a return of their original symptoms and signs. One girl was left with no adrenal tissue. The only complication was in a boy with a large, partly-resected malignant right adrenal tumor who had a subphrenic abscess drained and was left with a temporary bile fistula, cirrhosis, and chronic pain. All children were normotensive when discharged from hospital and remain alive and well with a follow-up of 7 to 36 years. There were no deaths. Long-term follow-up is essential. Key word Pheochromocytoma

Midodrine efficacy and pharmacokinetics in a patient with recurrent intradialytic hypotension

Recurrent intradialytic hypotension, a complication of hemodialysis, is a consequence of an inadequate compensatory response or a paradoxic response to ultrafiltration-induced volume reduction. We report the use of midodrine, an alpha agonist, in an 18-year-old man with Bardet-Biedl syndrome and recurrent intradialytic hypotension. The clinical features of the intradialytic hypotensive spells are consistent with a paradoxic withdrawal of sympathetic activity, although an underlying abnormality in autonomic dysfunction cannot be excluded. Midodrine significantly increased the intradialytic blood pressure and decreased the intradialytic hypotensive episodes requiring intervention. The pharmacokinetic characteristics of the prodrug midodrine and the active metabolite de-glymidodrine in this patient with end-stage renal disease approximate those reported for patients with normal renal function. However, the prolonged terminal half-life for the active metabolite, de-glymidodrine, warrants careful administration in patients with renal failure.

The team approach to the management of children on chronic peritoneal dialysis

The diagnosis of chronic renal failure has a profound and lasting impact on a child and family, with the potential for impairment of the child's physical, mental, and social development. To achieve an ideal outcome, the peritoneal dialysis (PD) team must focus on preparing the child and family to perform home dialysis, prescribe the dialysis regimen most compatible with the patient's lifestyle and clearance requirements, ensure optimal nutrition, and facilitate psychosocial adaptation to PD. Close follow-up is essential for early detection, prevention, and treatment of potential complications of dialysis. A multidisciplinary team approach encompassing nursing, medicine, nutrition, and social work best suits the needs of the child and family.

Effect of puberty on markers of glomerular hypertrophy and hypertension in IDDM

Epidemiological data implicate puberty as a factor in the initiation of diabetic nephropathy. However, the mechanism remains unclear. We hypothesized that puberty would result in an increase in glomerular hypertrophy and hypertension; these two early concomitant events are seen as pivotal to the pathophysiology of diabetic nephropathy. We studied the effect of pubertal duration on three surrogate markers of glomerular hypertrophy/hypertension: kidney volume (KV), microalbuminuria (MA), and Na-Li countertransport (CT). We recruited 177 subjects (87 female and 90 male; aged 6.2-22.1 years) with IDDM of 5 to 10 years' duration (6.8 +/- 1.6 years) into three groups with different pubertal duration: prepubertal since IDDM diagnosis; prepubertal at diagnosis, now pubertal; or early puberty at diagnosis, now postpubertal. KV was measured by ultrasound and corrected for body surface area; MA was defined as urinary albumin excretion of 15-200 micrograms/min in two of three 24-h samples, and Na-Li CT was measured in erythrocytes. As pubertal duration increased, there was a disproportionate increase in mean KV (prepubertal, 247 +/- 6 [SE] ml/1.73 m2; pubertal, 282 +/- 7/1.73 m2; postpubertal, 295 +/- 7/1.73 m2, P = 0.001), prevalence of nephromegaly (KV > 300 ml/1.73 m2) (14, 31, and 45%, respectively, P = 0.001), and prevalence of MA (0, 9.7, and 20.5%, respectively, P = 0.003). Subjects with KV > 300 ml/1.73 m2 were eight times more likely to have MA than those with KV < 300 (odds ratio 8.1, 95% confidence interval 2.4-27.4, P = 0.0001). There was no effect of pubertal duration on Na-Li CT. Multiple regression with KV as the dependent variable found an association with pubertal duration, MA, Na-Li CT, and current HbA1c (P < 0.0001). Our findings indicate that pubertal duration is an important determinant of both KV and MA and suggest that nephromegaly precedes microalbuminuria. We postulate that these effects are attributable to the influence of the pubertal milieu on glomerular hypertrophy/hypertension.

A crossover comparison of extended release felodipine with prolonged action nifedipine in hypertension

In a crossover design, control of blood pressure by extended release felodipine was compared with control by prolonged action nifedipine in 21 children with renal hypertension. Compliance with once daily felodipine was higher than with nifedipine, at 95.6 (SEM 2.7)% v 78.9 (6.0)% (p = 0.02). Mean diastolic blood pressure was lower during the day with felodipine than with nifedipine, at 77.6 (2.4) v 84.4 (2.8) mm Hg (p = 0.05). Similarly, blood pressure load (the percentage of the day during which the child had blood pressure exceeding the upper limits of normal for age) was lower for felodipine than for nifedipine: 43.5 (5.5)% v 61.3 (6.3)%. There was an opposite trend during the night, though this did not reach statistical significance. These data suggest that once a day felodipine is effective in children with hypertension. This may be because of improved compliance.

Plasma prorenin as an early marker of nephropathy in diabetic (IDDM) adolescents

We studied a group of 50 adolescents, average age 16 years, with diagnosed IDDM present for about seven years. Twenty-five had microalbuminuria (MA) averaging 111.0 +/- 34.0 (SEM) micrograms/min albumin excretion rate versus 6.7 +/- 7.4 micrograms/min in the 25 without MA. In other respects, such as sex ratio, age, body mass index, duration of IDDM, hemoglobin A1c, and normotensive systolic, diastolic and mean blood pressures (BP), these subgroups were closely matched. We compared them with a control group of 39 normotensive adolescents, of whom 18 were carefully matched siblings of the IDDM subjects with MA and 21 were similarly matched siblings of the IDDM non-MA subjects. Plasma renin concentration was determined by a direct radioimmunoassay method (Sanofi-Pasteur) and found to be virtually the same in the control and IDDM adolescents as a whole. There was also no real difference between the MA and non-MA subgroups. In contrast, plasma prorenin was significantly higher in the combined IDDM group (197.5 +/- 9.3 vs. control, 134.0 +/- 7.9 pg/ml, P < 0.0001). It was also higher in the MA subgroup than in the non-MA subgroup (226.4 +/- 13.6 vs. 168.5 +/- 10.1 pg/ml, P < 0.001). Interestingly, the 18 control siblings matching the MA subgroup had higher plasma prorenin than the 21 control siblings matching the non-MA subgroup (P < 0.001), suggesting a familial predisposition that precedes detectable diabetes and nephropathy. Our findings confirm and extend reports by other workers that elevated plasma prorenin is associated with incipient nephropathy, manifested by MA. The exclusive renal origin of this prorenin, its role in plasma, and the mechanism responsible for its elevation in IDDM with MA, are yet to be demonstrated, as is the general applicability of these findings to different populations of diabetics, with a higher incidence and severity of complications.

Pediatric clinical use of the ketoconazole/cyclosporin interaction

Ketoconazole is known to inhibit the metabolism of cyclosporin through inhibition of cytochrome P-450. This pharmacological interaction was used in an 8-year-old renal transplant patient to successfully achieve therapeutic cyclosporin blood concentrations. The addition of ketoconazole to the cyclosporin regimen should be considered when difficulties are encountered in attaining satisfactory cyclosporin levels.

Comparisons between oral and intraperitoneal 1,25-dihydroxyvitamin D3 therapy in children treated with peritoneal dialysis

Recent studies in adults have suggested that parenteral 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) may have advantages over oral therapy in the management of renal osteodystrophy. The purpose of this study was to determine whether there were clear differences between oral and IP 1,25(OH)2D3 treatments in children who did not pose a treatment problem. Seven children (5 males, 2 females, aged 1.8 to 16 years, median 4.8 years) undergoing peritoneal dialysis were initially treated with oral 1,25(OH)2D3 for a one month equilibration period They were randomly assigned to 3 months of either oral or intraperitoneal (IP) therapy with 1,25(OH)2D3 followed by 3-months-treatment using the alternative route. No significant differences in serum creatinine, phosphate, or parathyroid hormone concentrations were found between the different routes of administration in the patients. No significant differences in height standard deviation scores or renal osteodystrophy scores were found over the six-month study. Paired oral and IP pharmacokinetic studies were performed on these 7 patients and 2 other children who had been treated for at least 2 months using either oral or IP 1,25(OH)2D3. Serum was taken prior to one of the usual 1,25(OH)2D3 doses and 0.5, 1.5, 3, 6, and 24 h afterward. The highest measured concentrations of 1,25(OH)2D3 were found at 1.5 h for both oral and IP treatments (mean Cmax [SD]: oral 116 [23] pmol/l, IP 121 [24] pmol/l, p > 0.05). The AUC's for oral and IP therapy were similar (1701 [276] and 1645 [301] pmol/h/l, respectively). In the paired pharmacokinetic studies no significant differences were found between oral and IP treatments for the serum half life (27.4 [11.6] h and 19.2 [8.1] h, respectively) and total body clearance (15.3 [2.1] h and 18.4 [3.3] h, respectively) of 1,25(OH)2D3. In children who respond appropriately to oral 1,25(OH)2D3 there is no biological advantage to the use of IP 1,25(OH)2D3.

Sodium-lithium transport in adolescents with IDDM. Relationship to incipient nephropathy and glycemic control

OBJECTIVE

The aims of this study were to examine genetic and environmental influences in the development of early diabetic nephropathy and to assess the value of measuring membrane sodium transport as a marker for early nephropathy.

RESEARCH DESIGN AND METHODS

We measured erythrocyte sodium-lithium (Na-Li) countertransport, blood pressure (BP), HbA1c, and microalbuminuria (MA) in 84 adolescents with insulin-dependent diabetes mellitus (IDDM), 29 of whom had MA. Twenty-nine non-MA patients were selected and matched for age, sex, and IDDM duration with the 29 diabetic subjects with MA. The 84 diabetic adolescents were also compared with 85 nondiabetic siblings.

RESULTS

The erythrocyte Na-Li countertransport was significantly greater in the IDDM group than in the sibling group (mean +/- SD, 0.41 +/- 0.14 vs. 0.30 +/- 0.11 mmol Li.liters of erythrocytes-1.h-1, respectively, P < 0.0001), but a significant correlation was noted between the results in IDDM subjects and their siblings (r = 0.42, P < 0.0008). Na-Li countertransport was not different in the diabetic subjects with or without MA (0.43 +/- 0.13 vs. 0.37 +/- 0.13 mmol Li.liters of erythrocytes-1.h-1, respectively). There was a significant correlation in the IDDM group between recent diabetic control (HbA1c) and Na-Li countertransport (r = 0.37, P < 0.003). Diastolic BP was significantly higher in the IDDM group with MA than in those without MA (60 +/- 6 vs. 55 +/- 6 mmHg, respectively, P < 0.03).

CONCLUSIONS

These results suggest that erythrocyte Na-Li countertransport is influenced by the diabetic milieu. However, there was also evidence in our subjects of a genetic contribution to Na-Li countertransport as seen by the correlation between levels in the IDDM subjects and their siblings. Using Na-Li countertransport, we were not able to segregate those IDDM adolescents with and without early nephropathy.

Comparison of CAPD and CCPD in Children and their Limitations

Soon after its introduction, continuous ambulatory peritoneal dialysis (CAPD) became the choice mode of dialysis treatment for small children. With the advent of automated machines, continuous cycling peritoneal dialysis (CCPD) is now finding more favor in many centers. Initial cost of CCPD is higher due to the need for automated machines, but puts much less strain on the family. However, there is evidence that biochemical control is better with CAPD. Growth and nutrition in both groups are found to be similar. CCPD may have advantages over CAPD with regard to infection, since the former has fewer disconnections. The same is also true with regard to hernias and leaks. Some patients still prefer CAPD, since it allows more freedom in life style compared to CCPD.

Penoscrotal transposition: a case report and review

We report on a boy born with complete penoscrotal transposition, normal scrotum, twisted penile shaft with hypoplastic penile urethra, meatal stenosis, normal bladder, and bilateral cystic dysplastic kidneys. The patient died of renal failure at 2.5 months. This is the 13th reported case of complete penoscrotal transposition with normal scrotum. The possible pathogenesis is discussed and the literature is reviewed.

Pseudoporphyria cutanea tarda: two case reports on children receiving peritoneal dialysis and erythropoietin therapy

Pseudoporphyria cutanea tarda occurred in two children undergoing peritoneal dialysis and receiving erythropoietin therapy. The mechanism whereby erythropoietin might lead to photosensitization is unknown, but physicians should be aware of this possible association.

Inherited WT1 mutation in Denys-Drash syndrome

Patients with the Denys-Drash syndrome (Wilms' tumor, genital anomalies, and nephropathy) have been demonstrated to carry de novo constitutional mutations in WT1, the Wilms' tumor gene at chromosome 11p13. We report three new cases, two carrying a previously described WT1 exon 9 mutation and one with a novel WT1 exon 8 mutation. However, unlike patients in previous reports, one of our three patients inherited the affected allele from his phenotypically unaffected father. This observation indicates that the WT1 exon 9 mutation affecting 394Arg demonstrated in over one-half of the patients with the Denys-Drash syndrome may exhibit incomplete penetrance. Consequently, familial studies in patients affected by this syndrome are recommended.

The peritoneal equilibration test in children

The peritoneal equilibration test (PET) has been recommended in adults as a standardized means of estimating solute transport. Based on results of the PET, adult peritoneal permeability has been classified as high, high average, low average, and low. We performed a PET on 32 children aged 0.8 to 17.8 years (mean 9.3) using a dwell volume of 32 +/- 5 ml/kg of 2.5% dialysate. Dialysate to plasma (D/P) ratios for creatinine, urea, and sodium were calculated at two and four hours as were the ratios of dialysate glucose at two and four hours to the dialysate glucose at time 0 (D/Do). Stepwise logistic regression identified only the patients' age and D/Do glucose values at two hours as significant predictors of ultrafiltration. Net ultrafiltration after a four hour dwell could be predicted for 75% of children above 9.3 years, or whose D/Do glucose value at two hours was greater than 0.45. The mean and standard deviation values for D/Do glucose and D/P creatinine at four hours were 0.31 +/- 0.17 and 0.71 +/- 0.12, respectively. When children are characterized according to adult standards, at least 70% fall into the high or high average permeability categories.

Ambulatory blood pressure monitoring and left ventricular mass and function after successful surgical repair of coarctation of the aorta

Late cardiovascular morbidity and mortality remain significant despite apparently successful surgical repair of aortic coarctation. Alterations in cardiac function have been reported in normotensive patients who have had successful repair, the reasons for which remain unclear. This study addresses the relation between ambulatory blood pressure measurements and alterations in left ventricular performance in 20 patients with normotension at rest after successful repair of aortic coarctation. Exercise testing, ambulatory blood pressure monitoring and two-dimensional echocardiographic studies in 13 boys and 7 girls (mean age 14.2 +/- 2.31 and 14.7 +/- 3 years, respectively) who had no evidence of recoarctation were compared with the findings in 20 matched control subjects. No difference was found in systolic blood pressure at rest or peak exercise between patients and control subjects. Male patients developed a significant arm/leg gradient at peak exercise. Systolic ambulatory blood pressure was higher throughout the day in the male group. In the female group, systolic blood pressure was higher only during sleep. No difference was found in diastolic blood pressure or heart rate. The transverse aortic arch was smaller and the left ventricular mass greater in all patients. The relation of wall stress to rate-corrected velocity of shortening was 2 SD above normal in 8 of the 20 patients, suggesting that some have enhanced contractility. The E/A ratio on the atrial echocardiogram was significantly reduced in the patient group. Successfully treated patients who are normotensive at rest after operation are still at risk for developing end organ damage, which is probably explained by incipient mild hypertension documented by ambulatory blood pressure monitoring.

Captopril test in children with reflux nephropathy

We studied the plasma renin activity (PRA) and blood pressure (BP) responses to a single oral dose of captopril in children with renal scarring due to vesicoureteral reflux. The test was performed on 19 children, of whom 13 were normotensive and 6 hypertensive. Basal PRA was within the normal range for age for all except 1 patient. Mean basal PRA values for normotensive and hypertensive patients were not significantly different. At 90 min post captopril, the mean PRA increase was 3.61 ng/l per second (SD = 7.07) in the normotensive group but only 0.77 ng/l per second (SD = 0.83) in the hypertensive group. In 11 patients the average systolic BP 60-90 min post captopril was 0.9%-12.4% lower than the basal value. Diastolic BP decreased after captopril administration in 10 patients and increased in 9. The changes in mean arterial pressure and PRA between 0 and 90 min post captopril were inversely correlated (r = 0.605, P less than 0.01). Because of the PRA responsiveness in the normotensive patients with renal scarring, we suggest that there was activation of the renin-angiotensin axis in this group. However, it is not apparent whether such patients are more at risk of developing hypertension at a later time.

Medical and social outcome in adolescents with end-stage renal failure

Clinical information was collected on 118 adolescents who developed ESRF at age 143 months or older and were treated between 1966 and 1986 at the Toronto Hospital for Sick Children. The cumulative survival rate in transplanted patients (N = 109) was 80.1% after 15 years. Survival rates after four years were 93.9% in transplanted and 46.9% in nontransplanted patients (P less than 0.001). No patient receiving dialysis alone (N = 9) was followed longer than four years. Nine patients received three transplants and had an 89% survival rate. Six of these had a functioning graft at end of the follow-up. The cumulative survival of the entire group was 76.4% at eighteen years. Forty-two (35.6%) patients had a height below the third percentile. Functional status obtained by a structure telephone interview with a member of the present treating nephrology service was good (G) or excellent (E) for 66.7% of all patients (73.5% of transplant patients (N = 68) and 45% of dialysis patients (N = 20). Hemodialysis patients functioned less well [25% G/E (N = 12)] than peritoneal dialysis patients [75% G/E (N = 8)]. Most patients achieved an appropriate level of formal education although more slowly than normal adolescents. Only 11 patients were neither enrolled in an educational institution nor employed. We conclude that aggressive treatment for adolescents with ESRF is an appropriate application of health care resources.

Autosomal recessive inheritance of vasopressin-resistant diabetes insipidus

We report on 2 intellectually normal sisters with vasopressin-resistant (nephrogenic) diabetes insipidus (NDI). The sex of the patients, the history of parental consanguinity, and the fact that both parents formed normally concentrated urine suggested that the NDI in the 2 sisters was the result of inheritance of an autosomal recessive mutation affecting renal tubular water reabsorption. The results of DNA analysis of the DXS52 locus with the use of St14 as probe, shown by Knoers et al. [1988] to be tightly linked to the NDI locus on the X-chromosome, showed that each girl inherited different Xq28 regions of the maternal X chromosomes, ruling out a diagnosis of classical X-linked NDI.

Renal autotransplantation in children: a successful treatment for renovascular hypertension

Renovascular hypertension in children is not a common disease. With improved surgical technique the incidence of nephrectomy has decreased and renovascular reconstruction is currently the preferred method to manage this entity. Between 1977 and 1988, 21 patients with renovascular hypertension were treated at our hospital: 7 patients 6 to 16 years old underwent renal autotransplantation. Of the children 4 had unilateral and 3 had bilateral disease requiring bilateral autotransplantation. Autotransplantation was performed by anastomosis of each renal artery end-to-side to the common iliac artery. The renal veins were anastomosed end-to-side to the common iliac veins. The ureters were left intact in all but 1 patient who required a bench operation. Of the 4 patients who had a unilateral procedure 3 are cured and 1 is improved with a normal blood pressure on a small dose of antihypertensive medication. The 3 patients with bilateral autotransplants are cured. These results, with normalization of the blood pressure in 86% of the patients and improvement in blood pressure in 14% with a patency rate of 87%, are similar to other reported reconstructive modalities in children.

Tracer kinetics and actions of oral and intraperitoneal 1,25-dihydroxyvitamin D3 administration in rats

Tracer kinetic parameters of [3H]-1,25(OH)2D3 were calculated from data obtained following its acute oral (p.o.) or intraperitoneal (i.p.) administration. In normal rats studied after the tracer had distributed into the body, the slope and intercept of the log-serum [3H]-1,25(OH)2D3 versus time relationship were not significantly influenced by the route of administration. Pretreatment with 1,25(OH)2D3 (0.2 micrograms/100 g/day) by the same route as the tracer resulted in the following changes: in p.o. rats the serum [3H]-1,25(OH)2D3 intercept was much lower but the slope was not changed; in i.p. rats the intercept was not changed but the slope was increased. Both p.o. and i.p. treatment with 1,25(OH)2D3 lowered the weight gain and diet consumption, and increased serum calcium, kidney tissue calcium and urinary excretion of orally administered 45Ca. All the measures of bioactivity were greater in the i.p. dosed rats than in the p.o. dosed rats. We conclude that the p.o. 1,25(OH)2D3 was less potent because of diminished bioavailability due to self induction of its presystemic metabolism and inactivation.

Angiotensin converting enzyme inhibitor therapy to decrease microalbuminuria in normotensive children with insulin-dependent diabetes mellitus

It has been proposed that lowering glomerular pressure in children with insulin-dependent diabetes mellitus will reduce microalbuminuria and that this reduction may preserve renal function. We therefore conducted a double-blind, placebo-controlled, crossover trial to compare 3 months of treatment with the angiotensin converting enzyme inhibitor captopril (0.9 mg/kg/day), and 3 months of placebo administration to 12 normotensive adolescents with insulin-dependent diabetes mellitus, 11 with microalbuminuria (albumin excretion rate of 15 to 200 micrograms/min) and one with early overt nephropathy. Mean age (+/- SD) was 14.4 +/- 1.7 years, and disease duration was 5.1 +/- 2.5 years. Albumin excretion rate decreased significantly during captopril therapy (baseline 78 +/- 114 micrograms/min; mean of monthly measurements 38 +/- 55 micrograms/min vs placebo 78 +/- 140 micrograms/min; p less than 0.001). During captopril therapy, albumin excretion was reduced by 41 +/- 44% and decreased in 10 of 12 subjects, but was unchanged in two, one with a borderline albumin excretion rate (16.3 micrograms/min) and one with diabetes of short duration (2.9 years). Plasma renin activity rose significantly during captopril therapy, and mean arterial pressure decreased slightly (placebo 81 +/- 7 mm Hg; captopril 76 +/- 5 mm Hg; p = 0.004). After 3 months of captopril treatment, glomerular filtration rate and renal plasma flow did not change significantly. Hemoglobin Alc values remained stable during the study. The only side effect of captopril was diarrhea in one patient. We conclude that, in the short term, captopril is effective in decreasing albumin excretion rate in normotensive children with insulin-dependent diabetes mellitus and microalbuminuria, without significant side effects. Longer trials are indicated in an attempt to delay or prevent overt nephropathy.

Prolongation of acute renal failure in two patients with hemolytic-uremic syndrome due to excessive plasma infusion therapy

Two children with prototypic hemolytic-uremic syndrome had prolonged acute dialysis-dependent renal failure (74 and 84 days) associated with a state of hyperproteinemia induced by extensive infusion of fresh frozen plasma (283 and 307 units). We believe that the hyperproteinemia prolonged the duration of renal failure. Following cessation of plasma therapy, the hyperproteinemic state reversed, the degree of proteinuria decreased and renal function quickly recovered. Although the pathophysiological mechanism requires further evaluation, we speculate that an alteration in the colloid oncotic pressure and/or aggravation of tubulointerstitial injury due to overload-proteinuria may have increased the duration of renal failure.

Continuous flow peritoneal dialysis in pigs, using a silicone rubber double lumen catheter

Continuous flow (CFPD) and intermittent (IPD) peritoneal dialysis were compared in pigs, using a double lumen silicone rubber peritoneal dialysis catheter. For CFPD, after instillation of 30 ml/kg into the peritoneal cavity, dialysate was continually infused and drained at approximately 25 ml/kg/h. A dwell volume of 30 ml/kg was also used for IPD. Similar length cycles of each technique were compared in Experiment 1. In Experiment 2 total solute clearance and ultrafiltration achieved over two consecutive IPD cycles were compared with CFPD of a similar duration. The catheter functioned well with few complications. In Experiment 1, CFPD produced greater ultrafiltration and significantly improved the clearance of urea, potassium and phosphate compared to IPD. No significant difference between the techniques was observed in Experiment 2. Our data suggest that for CFPD to retain its advantage over IPD intermittent complete drainage of the peritoneal cavity may be necessary.

Naproxen-associated renal failure in a child with arthritis and inflammatory bowel disease

Renal failure occurred in a 14-year-old girl with peripheral arthritis associated with inflammatory bowel disease while she was being treated with naproxen. She had previously received aspirin and tolmetin sodium and had no complications. A renal biopsy showed a severe tubulointerstitial nephritis. Although her renal function improved somewhat with corticosteroid treatment, it worsened when the steroids were discontinued. This case emphasizes that renal failure can develop insidiously in children on nonsteroidal anti-inflammatory drug therapy and that such children must be monitored closely for signs of nephrotoxicity.

Effect of amino acid containing dialysis solutions on plasma amino acid profiles in children with chronic renal failure

Our previous studies demonstrated that, over single peritoneal dialysis cycles, amino acid-based dialysis solutions (AAD) were effective in dialyzing children with chronic renal failure (CRF) and offered metabolic advantages over traditional glucose dialysis solutions. The AAD, however, resulted in undesirable elevations of certain plasma amino acids, notably methionine. To further investigate the relationship between dialysate and plasma amino acid levels, we assessed the plasma amino acid response to a new AAD with relatively low methionine content (Vamin-based) over separate 5-h cycles with 1.3 and 2.3% AAD in eight patients with CRF (age 1-9 years) on continuous ambulatory peritoneal dialysis (CAPD). There was a net absorption of 70-73% of the amino acids, the net absorption of individual amino acids corresponding with the AAD composition. Plasma amino acid levels rose with AAD, peaking by 1 h postinfusion. Although most amino acids fell to preinfusion levels at the end of the cycle (including methionine), isoleucine with the 1.3% AAD and isoleucine, leucine, phenylalanine, and tyrosine with the 2.3% AAD remained significantly elevated. Having demonstrated in children that amino acids are absorbed from the peritoneal cavity in proportion to the AAD profile, modification of the current AAD is suggested.