Incompletely penetrant PKD1 alleles suggest a role for gene dosage in cyst initiation in polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) caused by mutations in PKD1 is significantly more severe than PKD2. Typically, ADPKD presents in adulthood but is rarely diagnosed in utero with enlarged, echogenic kidneys. Somatic mutations are thought crucial for cyst development, but gene dosage is also important since animal models with hypomorphic alleles develop cysts, but are viable as homozygotes. We screened for mutations in PKD1 and PKD2 in two consanguineous families and found PKD1 missense variants predicted to be pathogenic. In one family, two siblings homozygous for R3277C developed end stage renal disease at ages 75 and 62 years, while six heterozygotes had few cysts. In the other family, the father and two children with moderate to severe disease were homozygous for N3188S. In both families homozygous disease was associated with small cysts of relatively uniform size while marked cyst heterogeneity is typical of ADPKD. In another family, one patient diagnosed in childhood was found to be a compound heterozygote for the PKD1 variants R3105W and R2765C. All three families had evidence of developmental defects of the collecting system. Three additional ADPKD families with in utero onset had a truncating mutation in trans with either R3277C or R2765C. These cases suggest the presence of incompletely penetrant PKD1 alleles. The alleles alone may result in mild cystic disease; two such alleles cause typical to severe disease; and, in combination with an inactivating allele, are associated with early onset disease. Our study indicates that the dosage of functional PKD1 protein may be critical for cyst initiation.

The position of the polycystic kidney disease 1 (PKD1) gene mutation correlates with the severity of renal disease

The severity of renal cystic disease in the major form of autosomal dominant polycystic kidney disease (PKD1) is highly variable. Clinical data was analyzed from 324 mutation-characterized PKD1 patients (80 families) to document factors associated with the renal outcome. The mean age to end-stage renal disease (ESRD) was 54 yr, with no significant difference between men and women and no association with the angiotensin-converting enzyme polymorphism. Considerable intrafamilial variability was observed, reflecting the influences of genetic modifiers and environmental factors. However, significant differences in outcome were also found among families, with rare examples of unusually late-onset PKD1. Possible phenotype/genotype correlations were evaluated by estimating the effects of covariants on the time to ESRD using proportional hazards models. In the total population, the location of the mutation (in relation to the median position; nucleotide 7812), but not the type, was associated with the age at onset of ESRD. Patients with mutations in the 5' region had significantly more severe disease than the 3' group; median time to ESRD was 53 and 56 yr, respectively (P = 0.025), with less than half the chance of adequate renal function at 60 yr (18.9% and 39.7%, respectively). This study has shown that the position of the PKD1 mutation is significantly associated with earlier ESRD and questions whether PKD1 mutations simply inactivate all products of the gene.

Medical versus surgical treatment in children with severe bilateral vesicoureteric reflux and bilateral nephropathy: a randomised trial

BACKGROUND

Nephropathy associated with vesicoureteric reflux (VUR) and urinary tract infection can result in end-stage renal failure, hypertension, or both. Whether long-term VUR contributes to these outcomes is unknown. We compared, in a randomised trial, medical with surgical management of children with bilateral severe VUR and bilateral nephropathy.

METHODS

We stratified by age and glomerular filtration rate (GFR) 25 boys and 27 girls aged 1-12 years and randomly assigned them to medical or surgical management. At enrolment and 4 years' follow-up we estimated GFR from the plasma clearance of 51Cr-labelled edetic acid (EDTA), and did intravenous urography. We also did a metastable 99mTc-labelled dimercaptosuccinic acid (DMSA) assay and contrast cystography. The change in GFR at 4 years, expressed as a percentage change between enrolment and 4 years, was available for 26 of 27 patients in the medical and 24 of 25 in the surgical group. We assessed GFR in 48 patients 10 years after enrolment.

FINDINGS

Mean GFR at enrolment was 72.4 mL/min per 1.73 m(2) (SD 24.1) in the medical and 71.7 mL/min per 1.73 m(2) (22.6) in the surgical group. The mean percentage change in GFR at 4 years was 2.4% (SE 4.5) versus 4.7% (5.0) in the medical and surgical groups, respectively. The difference in change in GFR at 4 years between the two groups was not significant (7.1%, 95% CI 6.4% to 20.6%).

INTERPRETATION

Our data do not lend support to the view that the outcome for renal function is improved by surgical correction of VUR in children with bilateral disease.

Urinary supersaturation of calcium oxalate and phosphate in patients with X-linked hypophosphatemic rickets and in healthy schoolchildren

Nephrocalcinosis (NC) is a complication of the treatment of X-linked hypophosphatemic rickets (XLHR). Some studies have found that treated patients have enteric hyperoxaluria caused by phosphate therapy and have implicated calcium oxalate, whereas others have found only calcium phosphate in renal biopsy tissue.

AIM AND METHODS

We aimed to study the urinary supersaturation of calcium oxalate and calcium phosphate and to determine whether these measures are risk factors for NC. We collected 24-hour urine samples from 20 patients (12 girls) with XLHR, mean +/- SD age 8.2 +/- 4.7 years, and from 79 age-matched members of a healthy control group prospectively.

RESULTS

The median 24-hour urine excretions of oxalate, phosphate, and citrate (mmol/1.73 m(2) per day) were significantly increased in patients compared with the control group (oxalate 0.38 vs 0.28, P =. 0012; phosphate 63.1 vs 25.8, P <.0001; citrate 4.18 vs 2.7, P =. 0002). However, no significant differences were seen in the calcium oxalate or calcium phosphate between patients and the control group. No significant differences were seen in 24-hour urine calcium or magnesium excretion between patients and the control group; however, 8 patients had hypercalciuria. A significant higher urine volume in patients compared with the normal group (826 mL/m(2) 24-hour vs 597 mL/m(2) 24-hour; P <.005) was found. Twelve patients had NC at the time of investigation, and although the oxalate excretion was significantly higher in these patients, no significant difference was seen in the relative supersaturation of calcium oxalate monohydrate (CaC(2)O(4).H(2)O) compared with the 8 without NC.

CONCLUSIONS

Although 24-hour urine oxalate and phosphate excretion are increased in treated patients with XLHR, there is no increase in the supersaturation of either calcium oxalate or phosphate. Determination of the supersaturation of calcium oxalate or calcium phosphate does not predict the development of NC in XLHR.

Charge and size selectivity of proteinuria in children with idiopathic nephrotic syndrome

Experimental studies have pointed to charge selectivity as an important determinant of glomerular permeability to macromolecules. Loss of glomerular basement membrane (GBM) polyanion has been proposed as a cause of the selective proteinuria in minimal change nephrotic syndrome (MCNS). However, the presence of less-anionic albumin in urine than plasma from MCNS and focal and segmental glomerulosclerosis (FSGS) patients has been interpreted both as evidence for partial maintenance of charge selectivity and for involvement of other pathogenic mechanisms. The exact role of charge selectivity in the pathogenesis of nephrotic proteinuria remains controversial. We have examined the clearance of endogenous proteins of differing size and charge in children with idiopathic nephrotic syndrome (NS). Chromatofocusing was used to determine the isoelectric points (pIs) of albumins in paired plasma and urine samples from patients with FSGS (n = 6) and MCNS (n = 6). Charge selectivity was assessed by comparing the pIs of the fractions with the highest albumin concentration (model pI) in plasma and urine. The difference between the modal pIs was defined as the delta modal pI. Charge selectivity was also assessed from the albumin/transferrin and IgG4/IgG1 clearance ratios; size selectivity from the IgG1/albumin and IgG1/transferrin as well as the IgG4/albumin and IgG4/transferrin clearances. In children with FSGS, the mean (+/-SD) delta modal pI was -0.05 +/- 0.16, and in MCNS -0.05 +/- 0.11. Neither value differed significantly from zero. The albumin/transferrin clearance ratio showed no significant difference between FSGS and MCNS, but the IgG4/IgG1 clearance ratio was significantly higher in MCNS (P < 0.05). Size selectivity was significantly reduced in FSGS compared with MCNS (for IgG1/transferrin P < 0.01 and for IgG1/albumin P < 0.05). For IgG4/transferrin and IgG4/albumin, P was < 0.05. In conclusion, there was no evidence for residual charge selectivity in idiopathic NS associated with either MCNS or FSGS during nephrotic-range proteinuria. There was a significant loss of GBM size selectivity in children with FSGS with heavy proteinuria compared with children with MCNS with heavy proteinuria.

Salivary excretion of endogenous proteins in nephrotic syndrome in children

Size and charge selectivity of capillary permeability in the salivary glands of nephrotic children were investigated by measuring salivary excretion of endogenous plasma proteins of different size and charge. We examined 10 children with steroid-sensitive nephrotic syndrome (SSNS) in relapse and subsequent remission, 11 with steroid-resistant nephrotic syndrome, and 11 healthy children (controls). Albumin [mol. wt. 66 kilodaltons (kDa), isoelectric point (pI) 4.9] was measured by radio-immunoassay, transferrin (mol. wt. 77 kDa, pI 5.9) and immunoglobulins IgG1 (mol. wt. 150 kDa, pI 7-9) and IgG4 (mol. wt. 150 kDa, pI < 6) by enzyme-linked immunoabsorbent assay. In saliva, no significant differences were found between the four groups of children for any of the four proteins. Also, the saliva/plasma ratios of the four proteins were not different among the four groups. From these data, we conclude that in subjects with SSNS in relapse, neither size nor charge selectivity of salivary gland capillary permeability are affected.

Autosomal recessive polycystic kidney disease: long-term outcome of neonatal survivors

Autosomal recessive polycystic kidney disease causes renal and hepatic dysfunction in childhood. We describe the clinical outcome of 52 children with this diagnosis born between 1950 and 1993. Currently 23 are alive, 24 dead and 5 have been lost to follow-up; 1 has been dialysed and 7 transplanted. Life-table analysis of the patients surviving the 1st month of life revealed an actuarial renal survival of 86% at 1 year and 67% at 15 years. The probability of requiring anti-hypertensive treatment was 39% at 1 year and 60% at 15 years of age. Bleeding from gastro-oesophageal varices occurred in 8 patients at a mean age of 12.5 years, and was preceded by haematological evidence of hypersplenism in 6 of them. The study indicates a relatively good prognosis for patients with this condition who survive the neonatal period and emphasises the importance of early detection and appropriate management of systemic and portal hypertension.

Retrospective study of plasma exchange in patients with idiopathic rapidly progressive glomerulonephritis and vasculitis

A retrospective study of 48 patients was conducted to evaluate the efficacy of plasma exchange in children with idiopathic rapidly progressive glomerulonephritis (IRPGN), and renal or non-renal vasculitis. All patients were followed up at a single centre over a 15 year period. Treatment consisted of corticosteroids and/or cytotoxic agents. Plasma exchange was used in all patients because of severe renal involvement and/or clinical deterioration. One hundred per cent of patients with renal vasculitis who started plasma exchange within one month of disease onset and 58% of cases with IRPGN had significant improvement in renal function. No relapses of vasculitis were observed after treatment with plasma exchange in patients with renal and non-renal vasculitis. The results suggest that plasma exchange associated with immunosuppressive treatment could be of benefit in cases of IRPGN or vasculitis in terms of both renal and extrarenal recovery.

15-year follow-up of renin and blood pressure in reflux nephropathy

BACKGROUND

Beginning in 1978 a cohort of patients with reflux nephropathy first seen at a London Childrens hospital have had 5-yearly follow-ups. This is the fourth (15-year) report from that series.

METHODS

Of the original 100 normotensive children with reflux nephropathy 78 were traced for the 15-year study in 1994. Five patients were excluded because of nephrectomy, ten for other reasons, and eight refused to take part, leaving 55. 26 were on oral contraceptives. Supine blood pressure and plasma renin activity (PRA) were measured, and daily sodium excretion was assessed on a sample of overnight urine.

FINDINGS

Of the 55 patients (15 male, 40 female, median age 27 years, range 20-31), five had systolic and two had diastolic hypertension. Compared with the 10-year (1988) follow-up there was no change in blood pressure standard deviation scores (SDS) in this cohort. PRA showed an increasing dissociation from controls after 15 years of age and was significantly above that of controls by age 25. Exclusion of the patients on oral contraceptives did not significantly alter the results. The PRA values in 1988 were not individually predictive of the development of hypertension over the ensuing 5 years.

INTERPRETATION

Previously, in the long-term study of reflux nephropathy, blood pressure SDS had progressively increased with age. By 15 years blood pressure had levelled out and the PRA, though raised, did not predict the development of hypertension. Oral contraceptive use did not significantly modify the results.

Increased IL-2, IL-4 and interferon-gamma (IFN-gamma) in steroid-sensitive nephrotic syndrome

We investigated the production of cytokines by peripheral blood mononuclear cells (PBMC) and serum cytokine concentrations in children with steroid-sensitive idiopathic nephrotic syndrome (SSNS). PBMC from patients off treatment were collected during remission and relapse and cultured in medium alone or stimulated with calcium ionophore plus phorbol myristate acetate. Control PBMC were taken from healthy age-matched children. IL-2 was measured by bioassay, IL-4 by immunoradiometric assay, and IL-8 and IFN-gamma by ELISA. After 24 h culture without stimulation, IL-2, IL-4 and IFN-gamma were not detectable in the supernatant in any of the children. After stimulation, the supernatant concentrations of IL-2 (median 172 U/ml at 24 h) and IL-4 (160 pg/ml at 24 h; 210 pg/ml at 72 h) were significantly increased in relapse compared with remission (IL-2 37 U/ml; IL-4 65 pg/ml and 60 pg/ml) and controls (IL-2 69 U/ml; IL-4 40 pg/ml and 40 pg/ml) (P < 0.05). The concentration of IFN-gamma was not significantly increased in relapse compared with remission and controls (600, 325, and 145 U/ml, respectively, at 72 h). IL-8 concentrations were similar in relapse, remission and controls with stimulation (median 32, 40 and 40 ng/ml, respectively) and without (30, 17 and 10 ng/ml). IL-2 was not detectable in serum, but IL-4, IL-8 and IFN-gamma were measurable in about half the patients, both in relapse and remission, though were virtually undetectable in controls. We conclude that relapse of SSNS in children is associated with T lymphocyte activation with release of IL-2, IL-4 and IFN-gamma.

Persistent polyuria after posterior urethral valves

OBJECTIVE

To assess urinary concentrating ability, urine production and glomerular filtration rates in a cohort of boys with previously treated posterior urethral valves.

PATIENTS AND METHODS

Urinary concentrating capacity was assessed in 51 boys aged 5.4-9.9 years with previously treated posterior urethral valves. They all completed urinary frequency/volume charts, permitting calculation of 24 h urine volumes. The osmolality of an overnight urine collection was measured and, if < 800 mOsm/kg (n = 40), an intramuscular injection of desamino-cys-1-8-D-arginine vasopressin was given to determine the maximum concentrating ability. The glomerular filtration rate (GFR) was estimated from the plasma clearance of 51Cr-ethylenediamine tetra-acetic acid following a single intravenous injection.

RESULTS

The mean 24 h urine volume was 1025 +/- 448 (SD) mL. The mean overnight urine flow rate was 28.4 +/- 17.9 mL/h. Urinary concentrating capacity was impaired (< 800 mOsm/kg) in 30 (59%) of the boys and < 300 mOsm/kg in eight (16%). The mean GFR was 81 +/- 38 mL/min/1.73 m2SA. Significant correlations were noted between the GFR, the maximum urine concentration and the 24 h urine volume.

CONCLUSION

Persistent polyuria after valve ablation occurs in boys with posterior urethral valves. This has implications both in terms of urinary continence and on-going renal impairment.

Alternative treatment to corticosteroids in steroid sensitive idiopathic nephrotic syndrome

A review was undertaken of the use of alternative immunosuppressive treatment in addition to corticosteroids in a cohort of 429 children with steroid sensitive nephrotic syndrome (SSNS) treated between 1980 and 1994. Two hundred and twenty two children (52%) received at least one course of alternative treatment, 98 (23%) two, and 43 (10%) three. Cyclophosphamide was administered to 196 children (46%); in 181 it was the first course of alternative treatment and in 104 (57%) of those it was also the last ('final course'). Levamisole was given to 56 children (13%) and cyclosporin to 53 (12%). Fifteen children in whom cyclosporin failed were treated with chlorambucil. A few patients received azathioprine or vincristine. Ten children developed secondary steroid resistance, of whom five progressed to chronic renal failure. Acute complications included reversible renal failure, septicaemia, peritonitis, convulsions, and cerebral thrombosis. There were three deaths. It is concluded that half of the referred children with SSNS were deemed to require at least one course of alternative immunosuppressive treatment, and that side effects of the treatment and complications of SSNS are infrequent but occasionally fatal.

Serum intact parathyroid hormone and ionised calcium concentration in children with renal insufficiency

We report our experience of the use of an immunoradiometric assay for intact parathyroid hormone (i-PTH) and the measurement of plasma ionised calcium concentration (PCa2+) in 73 children with chronic renal insufficiency (CRI); plasma creatinine concentration (PCr) 52-856 mumol/l. There was a poor correlation between i-PTH and PCr (r = 0.10, n = 552) compared with that for C-terminal PTH and PCr (r = 0.60, n = 248), suggesting that the i-PTH assay is independent of renal function in this group of treated children. A clear response of i-PTH to a low total plasma Ca (tPCa) and PCa2+ was observed. There was a significant positive correlation between both tPCa and PCa2+ (r = 0.50, n = 389) and the fraction of Ca2+ (the fraction of tCa which was ionised) and PCa2+ (r = 0.50, n = 389). The finding of a low or normal PCa2+ with a low calculated fraction of Ca2+ was frequently observed, i.e. the measured tPCa was unexpectedly high, suggesting complexing of Ca2+ by accumulated anions in CRI. There was a poor relationship between the plasma albumin concentration and both bound plus complexed Ca (tPCa minus PCa2+) and the fraction of Ca2+ (r = 0.15 and -0.17, respectively). The positive predictive value for a raised i-PTH of a tubular reabsorption of phosphate of less than 80% was 0.87, and of an alkaline phosphatase greater than 800 U/l was 0.37.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term cyclosporin A treatment of minimal-change nephrotic syndrome of childhood

We evaluated the efficacy of long-term cyclosporin A (CyA) treatment in the maintenance of remission in 40 children with steroid-dependent minimal-change nephrotic syndrome (MCNS). CyA was given in an initial dose of 5 mg/kg per day, adjusted to maintain a trough whole blood level of 50-150 ng/ml. All the 40 children received CyA for 1 year. In 18 patients, CyA was continued for a further period of at least a year without interruption; 9 patients had a second course of CyA therapy after an interval of at least 1 month. Of the 40 children 29 (72%) had one or more relapses during treatment with CyA, with 16 (40%) relapsing during the 1st year. During the second period of CyA, 10 (56%) of the 18 children treated continuously relapsed, whereas all the 9 children who had an interrupted course of therapy relapsed. CyA was discontinued at one time in 27 patients, all of whom subsequently relapsed, with a median time to relapse of 26 days. Long-term prednisolone in addition to CyA was required to maintain remission in 16 (40%) of the whole group. The results suggest that the long-term use of CyA is able to maintain remission of MCNS, although 40% of the patients also required low-dose alternate-day steroids; patients appeared to fare worse if the CyA course was interrupted; no patient experienced a long-term remission after CyA was stopped.

Effect of cyclosporin A on glomerular filtration rate in children with minimal change nephrotic syndrome

Cyclosporin A (CyA) is now commonly used in the management of children with steroid-dependent nephrotic syndrome. In order to assess nephrotoxicity related to CyA therapy, we measured glomerular filtration rate (GFR) on 123 occasions in 24 children with minimal change nephrotic syndrome receiving CyA. GFR was estimated from the plasma clearance of 51chromium-EDTA every 3 months during CyA therapy of up to 27 months duration. There was a significant reduction in GFR after 3 months of CyA therapy [118 +/- 33 (SD) to 93 +/- 24 ml/min per 1.73 m2] but no further fall thereafter, although the reduction in GFR was sustained for the duration of CyA therapy. This reduction in GFR appeared to be reversible upon cessation of CyA, but careful monitoring of renal function is necessary in such patients to prevent the development of longer term nephrotoxic sequelae.

Lymphocyte subpopulations, interleukin-2 and interleukin-2 receptor expression in childhood nephrotic syndrome

Abnormal T lymphocyte function and reduced interleukin-2 (IL-2) production have been implicated in the pathogenesis of the nephrotic syndrome (NS). We investigated: (1) lymphocyte subpopulations and expression of IL-2 receptor (IL-2R) on T cells using two-colour flow cytometry, (2) serum IL-2 and (3) the soluble component of IL-2R (sIL-2R) in serum, using enzyme-linked immunosorbent assay, in 38 children with NS. All children, except those in remission, had marked proteinuria. They were divided into groups according to renal pathology: (1) steroid-sensitive NS (SSNS) not receiving prednisolone therapy, (2) SSNS on prednisolone, (3) focal segmental glomerulosclerosis (FSGS), (4) SSNS in remission and not receiving prednisolone therapy, (5) congenital NS (CNS). Results were compared with 26 age-matched controls. Total T lymphocytes (CD3) were reduced in groups 1 and 2; CD4 count was reduced in groups 1-4; CD8 count increased in groups 2 and 3; CD8 and CD19 (B lymphocytes) were significantly reduced in group 5. Increased IL-2R expression (CD25) on CD4 lymphocytes was noted in groups 1, 2 and 3 implying activation of these cells. In patients with SSNS, increased serum sIL-2R was recorded during relapse (1,273 +/- 497 U/l vs. 913 +/- 401 U/l in remission, P < 0.005) but free serum IL-2 was not detectable at any stage. The specific alterations in lymphocyte subpopulations in SSNS and FSGS would imply an involvement of the immune system distinct from that in CNS.

An electrophysiological study on children and young adults with Alport's syndrome

Alport's syndrome is characterised by progressive haematuric nephritis and high tone sensorineural hearing loss. Ocular signs are variable, the most consistent findings being anterior lenticonus and retinal flecks in the macula and mid peripheral areas. Previous electrophysiological studies on patients with Alport's syndrome have mostly been on adult patients undergoing haemodialysis, or after renal transplantation. A group of young patients with Alport's syndrome were studied to assess if early electrophysiological changes were detectable. A total of 20 patients (15 males and five females) between the ages of 3.5 and 22 years (mean 12.7 (years) were examined and compared with control subjects. Visual evoked potentials and electroretinograms were obtained following flash and pattern reversal stimulation. Electro-oculograms were also recorded. No significant electrophysiological changes were found in any of the 20 patients, including four who had visible fundus changes.

Tubular proteinuria in steroid sensitive multi-relapsing nephrotic syndrome

The urinary excretion of N-acetyl-beta-D-glucosaminidase (UNAG) and retinol binding protein (URBP) was studied in 65 children with steroid sensitive multirelapsing nephrotic syndrome (MRNS): 28 on cyclosporin A (CyA) therapy, 22 on prednisolone (P), 15 off-treatment and in 32 normal children to assess renal tubular damage or dysfunction. The urinary protein excretion was expressed in relation to that of creatinine (UNAG/UC in mumol pnp/h/mmol; URBP/UC in microgram/mmol). There was a weak but significantly negative correlation between age and both, UNAG/UC (r = -0.38, p < 0.01) and URBP/UC (r = -0.50, p < 0.05) in normal children, but not in nephrotics. In normals and in patients off steroids an association between these two proteins was found (r = 0.38, p < 0.05; r = 0.56, p < 0.05 respectively). Geometric mean UNAG/UC was significantly higher in nephrotics on CyA therapy (26.5 +/- 4.0), and on P (37.0 +/- 7.9) as well as in those off-treatment (16.3 +/- 3.1) compared to normal children (9.3 +/- 3.4). There was a further increase in those with raised urinary albumin: creatinine ratio (UA/UC) (> 0.1 mg/mg). URBP/UC was not increased in any of the groups of children with MRNS. Raised NAG in urine may therefore indicate active nephrotic syndrome rather than being due to the drug therapy.

Atypical (non-diarrhea-associated) hemolytic-uremic syndrome in childhood

We describe the clinical and laboratory features of 20 children who were seen during the past 20 years with idiopathic nondiarrhea-associated hemolytic-uremic syndrome. There was no seasonal variation in time of onset; a genetic pre-disposition seemed likely in two of the cases. The prodromal illness was nonspecific and by definition did not include diarrhea. Hypertension was a major problem in the majority of the patients. Five died, three during the initial illness; four are in end-stage renal failure, and all but two of the survivors have residual nephropathy. Eleven patients had a "relapsing" course; up to eight additional documented episodes of hemolytic-uremic syndrome occurred in individual patients. Of the nine children treated before 1980, three died shortly after onset, two never recovered function after the initial illness, one had a relapsing course and died later, and one had residual nephropathy. Plasma exchange was introduced for the management of non-diarrhea-associated hemolytic-uremic syndrome in 1980; since then, all of the 11 patients have recovered function after the initial episode, but 10 of them had relapses. It appears that with the introduction of plasma exchange there has been an improved outcome in the initial phase, but the survivors tend to have relapses. Atypical (non-diarrhea-associated) hemolytic-uremic syndrome is a heterogeneous yet distinct subgroup of hemolytic-uremic syndrome that differs from diarrhea-associated hemolytic-uremic syndrome on epidemiologic, clinical, laboratory, histologic, and prognostic grounds.

Foregut motor function in chronic renal failure

In children with chronic renal failure (CRF) anorexia, nausea, and vomiting are common yet poorly understood symptoms. We studied oesophageal and gastric motor function in 12 children (age 7 months-6.8 years) with severe CRF not undergoing dialysis who had persistent anorexia and vomiting. Eight of 12 patients had significant gastro-oesophageal reflux (reflux index 5.2% to 21.9%, mean 11.3%; controls < 5%), 7/10 had altered gastric half emptying times (T1/2) for 5% glucose or milk (glucose meal--controls: 8-14 min, two CRF patients: 18-25 min; milk meal--controls: 48-72 min, five CRF patients 27, 28, 82, 83, and 110 min). Gastric antral electrical control activity was abnormal in 6/11 patients, with different types of gastric dysrhythmias whereas the remainder and controls showed a regular dominant frequency of 0.05 Hz. In 7/9 patients fasting serum gastrin concentration was raised (53 to > 400, mean 168 pmol/l, controls < 40 pmol/l). All CRF patients with anorexia and vomiting had one or more disorder of foregut motility. The nature and variety of the motor disorders and the raised concentrations of circulating gastrin suggest that the normal environment generated by CRF affects the function of the smooth muscle of the foregut.

Interleukin-8 and polymorphoneutrophil leucocyte activation in hemolytic uremic syndrome of childhood

Polymorphoneutrophil leucocytes (PMNLs) are implicated in the pathogenesis of diarrhea-associated hemolytic uremic syndrome (D+ HUS). We investigated mechanisms of PMNL involvement by measuring tumor necrosis factor alpha (TNF alpha) and the novel cytokine, interleukin-8 (IL-8), a potent activator of neutrophils, together with alpha 1- antitrypsin-complexed elastase (alpha 1-AT-E) as a marker of neutrophil degranulation, and anti-neutrophil cytoplasmic antibodies (ANCA). IL-8 was not detected in the 17 normal children, but was significantly elevated in 20 of 25 D+ HUS children (P less than 0.005), and in three of nine children with non-diarrhea-associated (D-) HUS. Sequential data showed that IL-8 peaked transiently in the circulation, reaching a maximum just before a more protracted burst of alpha 1-AT-E. The IL-8 levels correlated significantly with circulating alpha 1-AT-E concentrations (r = 0.50, P less than 0.05). In D+ HUS IL-8 levels also correlated with the PMNL count (r = 0.63, P less than 0.005), and the highest values were seen in those children who died in the acute phase of the disease. TNF alpha was raised in only 1 of 16 D+ HUS children and in no patients were ANCA detected. The data suggest that PMNLs in HUS are recruited by IL-8, that this cytokine plays a key role in the PMNL activation which occurs, and that agents which suppress this recruitment and activation might play a therapeutic role in this disorder.

Management of hypertensive emergencies

Between 1975 and 1985, 454 patients with hypertension were admitted to the Renal Unit of the Hospital for Sick Children. A total of 110 (24%) patients presented with severely raised blood pressures deemed to require emergency management. At presentation 84/110 had symptoms and signs of long standing hypertension with neurological involvement. Between 1975 and 1980 bolus intravenous injections of diazoxide and/or hydralazine were used with the aim of reducing the blood pressure to within the normal range for age in the first 12-24 hours after admission. Of 57 patients treated in this way 13 developed hypotensive complications and four, whose blood pressures returned to normal within 24 hours of admission, suffered irreversible neurological damage. Subsequently, the management changed to the use of intravenous infusions of labetalol (1-3 mg/kg/hour) and/or sodium nitroprusside (0.5-8 micrograms/kg/min) to enable a more gradual controlled reduction of blood pressure over the first 96 hours of admission. Between 1980 and 1985, 53 patients were treated using this regimen. In all cases blood pressure reduction was achieved in a more controlled manner without further neurological impairment or serious irreversible side effects. From our experience, the use of labetalol and sodium nitroprusside by incremental infusion in the critical early phase of management has resulted in improved control of accelerated hypertension without the sudden hypotensive episodes seen when bolus injections are used.

Renovascular disease in childhood

Fifty-four children referred for investigation of hypertension had renovascular disease. In eight patients it was associated with neurofibromatosis, in three with idiopathic hypercalcemia of infancy, and in five cases it followed an arteritic illness. Fibromuscular dysplasia was the underlying abnormality in the majority of cases (46%). Twenty-six patients (48%) were first seen with accelerated hypertension; 38 children (70%) had bilateral renal arterial disease, and in 41 (76%), disease of the small intrarenal vessels was found. Renal vein renin ratios indicated unilateral disease in 31 cases; the results correlated with arteriography findings in 32 (62%) of 51 patients. Eleven children also had the middle aortic syndrome, and 9 of 16 patients, investigated by cerebral arteriography because of cranial bruits or focal neurologic signs, had cerebral vascular abnormalities. Twenty patients were treated surgically--10 by reconstructive procedures, 11 by nephrectomy or heminephrectomy, and 6 by transluminal angioplasty. Of these, 9 (45%) are normotensive with no treatment, 10 have a decreased requirement for antihypertensive drugs, and 1 had no improvement. Thirty-four patients were treated medically because of the extent of their disease; two patients have died of hypertensive complications. We conclude that renal vascular disease in children is often widespread, may be associated with intracerebral vascular disease, frequently affects both kidneys, including both intrarenal and extrarenal vessels, and is therefore not always amenable to surgical intervention and cure.

Ophthalmologic assessment of young patients with Alport syndrome

BACKGROUND

Alport syndrome is an X-linked disease affecting basement membrane collagen. It is characterized by nephritis associated with high-tone sensorineural hearing impairment and ophthalmic signs. Although ocular changes have been described in adults, few data exist regarding the incidence of abnormal ocular features in adolescence and childhood.

METHODS

Fifteen male and five female patients with Alport syndrome underwent ophthalmologic, audiologic, and nephrologic assessments. All patients studied had hematuria and a positive family history of Alport syndrome. Thirteen patients had a renal biopsy that showed characteristic electron microscopic changes of the disease. Eleven patients had high-tone sensorineural impairment. Electrophysiologic investigations performed included electroretinography, visual-evoked potentials, and electro-oculography.

RESULTS

Two patients had early signs of anterior lenticonus, three had flecks in the retina, and two patients also had posterior subcapsular cataracts. None of the patients had significant electrophysiologic abnormalities.

CONCLUSION

These findings indicate that ocular changes are uncommon and subtle in young patients with Alport syndrome, and suggest that the signs increase in frequency and severity with age.

Crescentic glomerulonephritis in children

Data on patients with crescentic glomerulonephritis (greater than 50% glomeruli with crescents), referred to the Hospital for Sick Children during the past 13 years, were reviewed. Thirty patients (13 male, 17 female) aged 3.7-15.7 years (mean 9.5) were evaluated. Initial clinical features included: oedema (24/30), hypertension (19/30), gross haematuria (15/30), oliguria (15/30) and a decreased glomerular filtration rate (GFR less than 30 ml/min per 1.73 m2) (22/30). Henoch-Schönlein purpura was present in 9 patients, microscopic polyarteritis in 3, polyarteritis nodosa in 1, Wegener's granulomatosis in 1, systemic lupus erythematosus in 1, post-streptococcal glomerulonephritis in 2, mesangiocapillary glomerulonephritis in 7, anti-glomerular basement membrane glomerulonephritis in 2, and 4 were idiopathic. In 10 patients 50%-79% of glomeruli were affected by crescentic changes (group 1) and in the remaining 20, 80% or more (group 2). The crescents were cellular, fibrocellular or fibrous, and the degree of sclerosis was assessed. Patients in both groups were treated with plasma exchange, corticosteroids, anticoagulants, cyclophosphamide and azathioprine in different combinations. On follow-up, 3 patients were dead, 1 was lost to follow-up, 12 were on dialysis/transplant programmes, 4 had a GFR of less than 30 and 10 a GFR of more than 30 ml/min per 1.73 m2. In our experience, 50% progressed to end-stage renal failure. The interval between disease onset and start of treatment was a prognostic factor for outcome. Fibrous crescents were associated with a worse outcome than fibrocellular crescents (P less than 0.05). Outcome was not, however, related to the percentage of glomeruli affected (P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Cadaveric renal transplantation in children under 5 years of age

From March 1987 to August 1990 23 cadaveric renal transplants were performed in 19 children under the age of 5 years at the time of transplantation. The mean age of the recipients was 3.3 years (range 1.3-4.7) and the mean weight 13.0 kg (range 9.3-19.2). The mean donor age was 7.8 years (range 1.5-25). All children received triple immunosuppression with prednisolone, cyclosporin A and azathioprine, and 4 who had 2 grafts during this period also received antithymocyte globulin at the time of the second transplant. Patient survival is 100%. Actuarial first cadaveric graft survival was 57% at 1 year and remains unchanged at 3 years. There were 10 graft losses, 4 were associated with renal venous thrombosis without apparent rejection. Two were lost due to acute vascular rejection with associated renal venous thrombosis, and the remaining 4 losses followed cellular or chronic vascular rejection. The mean glomerular filtration rate +/- SD was 51.4 +/- 23.6 ml/min per 1.73 m2 (n = 11) at 1 year and 43.5 +/- 25.3 at 2 years (n = 6). The mean height standard deviation score improved from -2.2 +/- 1.1 at the time of transplantation to -1.3 +/- 1.0 1 year post transplant (n = 11). The immunosuppression was well tolerated with a low incidence of side effects. Cadaveric renal transplantation remains a difficult but rewarding undertaking in children under 5 years of age.

Duplex Doppler ultrasound in the investigation of occult nephropathy following haemolytic uraemic syndrome

Duplex doppler ultrasound has been reported to be of value in the detection of raised vascular resistance, particularly in the renal tract. A prospective single blind study investigating the use of duplex Doppler ultrasound to measure resistive index (RI) in patients with impaired renal function and a history of diarrhoea-associated haemolytic uraemic syndrome (D+ HUS) was performed. There was considerable overlap in the range of RIs, with RIs greater than 70% in children with normal renal function and in those with renal impairment following D+ HUS. There was no significant difference in the mean RI between the groups studied. We feel that the RI is not of value in predicting the presence of occult nephropathy following haemolytic uraemic syndrome.

Neutrophil activation in the haemolytic uraemic syndrome: free and complexed elastase in plasma

There is evidence of neutrophil involvement in the pathogenesis of the haemolytic uraemic syndrome (HUS), and neutrophil release products are thought to cause endothelial cell damage. Elastase is the major lysosomal proteinase liberated by activated neutrophils. In this study we measured both free and complexed elastase. No free elastase activity could be detected in the plasma of patients with diarrhoea-associated (D+) HUS using a specific substrate. However, there was a marked increase in alpha 1-antitrypsin (alpha 1-AT) complexed elastase as measured by a newly developed enzyme-linked immunosorbent assay not only in D+ HUS, but also in non-diarrhoea-associated (D-) HUS. This finding is independent of either a high polymorphonuclear leucocyte count or renal failure. This increase in bound elastase together with our sequential data which demonstrate raised alpha 1-AT complexed elastase levels early in the disease process further support the theory that neutrophil activation is one of the key events in the pathophysiology of this disorder.

Prediction of blood pressure from plasma renin activity in reflux nephropathy

As there is a 10% risk of hypertension developing in children with reflux nephropathy and the renin-angiotensin system has been implicated in its aetiology, a long term prospective study has been undertaken to explore the relationship between plasma renin activity (PRA) and blood pressure in such patients. In 1978, of 100 normotensive children with reflux nephropathy 8% were shown to have PRA above normal. Five years later of 85 subjects suitable for analysis 13% had increased PRA and it was shown that PRA and blood pressure SD scores significantly increased. The present study refers to the 10 year follow up in which 95 of the original group were traced but eight of these were unavailable for study and 28 others were excluded from analysis because of extraneous factors that might influence blood pressure or PRA. Results therefore on 59 have been analysed. PRA was above normal in 13/59 (20%) subjects, and PRA and blood pressure SD scores had further increased. The data continue to support the role of the renin-angiotensin system in the observed rise of blood pressure in reflux nephropathy, but individual PRA measurements do not appear so far to predict reliably the onset of hypertension in affected patients.

Long term renal outcome of childhood haemolytic uraemic syndrome

OBJECTIVE

To evaluate the long term outcome of renal function in infants and children after diarrhoea associated haemolytic uraemic syndrome.

SETTING

The Hospital for Sick Children, Great Ormond Street, and the Royal Free Hospital, London.

SUBJECTS

103 children with the syndrome who presented between 1966 and 1985; 88 attended for follow up investigations (40 male, 48 female) with a mean age 11.6 (range 5.2-22.6) years and a mean duration of follow up of 8.5 (range 5.1-21.3) years.

MAIN OUTCOME MEASURES

Blood pressure, ratio of early morning urine albumin to creatinine concentration, glomerular filtration rate, and plasma renin activity.

RESULTS

The mean (SD) systolic blood pressure standard deviation score was 0.38 (0.67) and diastolic blood pressure SD score was 0.10 (0.76). The geometric mean ratio of overnight urine albumin to creatinine concentration was 1.27 (range 0.03-48.2), significantly higher than the value observed in 77 normal children (0.32 (0.05-1.95), p less than 0.0001). Glomerular filtration rate estimated from the plasma clearance of chromium-51 EDTA was 95.1 (22.7) ml/min/1.73 m2 surface area, and 16 children had a rate of less than or equal to 80 ml/min/1.73 m2. Significant negative correlations were found between glomerular filtration rate and urinary albumin to creatinine ratio (r = -0.41, p less than 0.0001) and glomerular filtration rate and systolic blood pressure SD score (r = -0.48, p less than 0.0001). A significant positive correlation was found between urinary albumin to creatinine ratio and systolic blood pressure SD score (r = 0.25, p = 0.02).

CONCLUSIONS

After an acute episode of diarrhoea associated haemolytic uraemic syndrome 31% (27/88) of children had an increased albumin excretion, 18% (16/88) had a reduced glomerular filtration rate and 10% (9/88) had both, in association with a higher systolic blood pressure, indicating considerable residual nephropathy in this group.

Urine glycosaminoglycans in congenital and acquired nephrotic syndrome

To evaluate the specificity of a raised heparan sulphate (HS) excretion previously reported in four children with congenital nephrotic syndrome (CNS), we measured the urinary excretion of HS and chondroitin sulphate (CS) in seven children with Finnish-type congenital nephrotic syndrome (CNSF), seven with diffuse mesangial sclerosis (DMS), nine with focal segmental glomerulosclerosis (FSGS), 14 with steroid-sensitive nephrotic syndrome of whom eight had a biopsy confirming minimal change histology (SSNS), and 17 controls. The urine HS/CS ratio in normal children had a median of 0.36 (observed range 0.21 to 0.68) and was independent of age. HS/CS ratio was significantly greater than controls in CNSF (median 0.80, range 0.43 to 1.28), DMS (median 0.81, range 0.49 to 1.13) and FSGS children (median 0.66, range 0.38 to 1.6), but was not in SSNS (median 0.44, range 0.28 to 0.70). There was a positive correlation between the HS/CS ratio and urine albumin excretion. High HS/CS ratios are not diagnostic of a particular histological variety of CNS.

Urinary oxalate and glycolate excretion and plasma oxalate concentration

The diagnosis of primary hyperoxaluria in young children is hampered by the lack of a reliable reference range for urinary oxalate excretion, especially in infants. We present data on urinary oxalate and glycolate excretion in 137 normal children, on the plasma oxalate concentration in 33 normal children and 53 with chronic renal failure, and on amniotic fluid oxalate concentration in 63 uncomplicated pregnancies. The urinary oxalate:creatinine molar ratios were log normally distributed: mean (range) values were less than 1 year 0.061 (0.015-0.26), 1-5 years 0.036 (0.011-0.12), 5-12 years 0.030 (0.0059-0.15), and greater than 12 years 0.013 (0.0021-0.083). Geometric mean (range) plasma oxalate concentration in the normal children was 1.53 (0.78-3.02) mumols/l and was independent of age. The mean (SD) plasma oxalate: creatinine molar ratio in these normal children and 50 with chronic renal failure was 0.033 (0.013), and was independent of age and renal function. Mean (SD) amniotic fluid oxalate concentration was 19.0 (4.3) mumols/l.

Partial reversibility of cisplatin nephrotoxicity in children

To evaluate the long-term renal toxicity of cisplatin, 40 children who had been without treatment at least 18 months (range 18 months to 7 years) were observed. In all the children, glomerular filtration rate (GFR) was estimated from the plasma clearance of chromium 51-labeled ethylenediaminetetraacetic acid, both at the end of treatment and at a median follow-up of 2 years 6 months after treatment was stopped (range 18 months to 7 years). In 21 children, serum magnesium level was also measured at follow-up. Median age at diagnosis was 15 months (range 13 days to 13 years 8 months), and median cumulative doses of cisplatin was 500 mg/m2 (range 120 to 1860 mg/m2). In 22 of 24 children with an end-of-treatment GFR of less than 80 ml/min per 1.73 m2, the median improvement in GFR at follow-up was 22 ml/min per 1.73 m2 (range 2 to 56 ml/min per 1.73 m2). Hypomagnesemia was found in 6 of 21 children and was independent of GFR. No significant correlation was found between improvement in renal function and total cisplatin dose, age, gender, tumor type, or associated nephrotoxic medication. We conclude that most children have some recovery from cisplatin glomerular toxicity, especially if damage is not severe, but that hypomagnesemia may persist.

Molecular analysis of chromosome region 11p13 in patients with Drash syndrome

The association of nephropathy, Wilms' tumour and genital abnormalities is known as Drash syndrome. Two of these features are also seen in the WAGR (Wilms' tumour, aniridia, genito-urinary abnormalities, mental retardation) complex, known to be associated with deletions of chromosome region 11p13. We have carried out karyotypic and molecular studies in 10 Drash patients, 5 males and 5 females. All the males had a 46XY karyotype as did 3/5 of the phenotypic females, the other two having a 46XX karyotype. One of the 46XX females also had a deletion of region 11p13-p12, the only detectable autosomal chromosome abnormality in any of the patients studied. Lymphoblastoid cell lines were prepared from 6 of the Drash patients and were used in dosage studies using a variety of DNA probes from the 11p13 region. There was no evidence of microdeletions in any patient with a normal karyotype. Because of the 46XY karyotype in phenotypic females, selected X and Y chromosome loci were analysed and all found to be normal. Although Drash syndrome is likely to be of genetic origin, there are no readily detected deletions within the 11p13 region.

Clinicopathologic review of twelve children with nephropathy, Wilms tumor, and genital abnormalities (Drash syndrome)

The clinicopathologic and radiologic features of 12 children with complete and incomplete forms of Drash syndrome are reported. Their common denominator was a nephropathy. Four had the full triad, consisting of nephropathy, Wilms tumor, and genital abnormalities; five had nephropathy and genital abnormalities, and three had nephropathy and Wilms tumor. Of the 11 children who had proteinuria, eight had the nephrotic syndrome. Of the 10 whose condition progressed to end-stage renal failure, seven were less than 3 years of age. The histologic features of Wilms tumor were favorable in all seven children, and the tumor was bilateral in three. Of the nine patients who had genital abnormalities, eight had 46,XY karyotype and either ambiguous genitalia (six patients) or normal female phenotype (two). One other patient had a normal 46,XX female karyotype and phenotype but had both müllerian and wolffian structures and a streak ovary. Nine patients had a distinct pelvicaliceal abnormality not previously reported as a feature of this syndrome. Other congenital abnormalities were aniridia, mental retardation, deafness, nystagmus, and cleft palate. This syndrome must be considered in any infant with unexplained nephropathy, particularly in young phenotypic female infants and in those children with ambiguous genitalia or Wilms tumor with an early presentation.

The postnatal management of hydronephrosis diagnosed by prenatal ultrasound

A total of 112 patients (142 kidneys) presented with hydronephrosis consistent with ureteropelvic junction obstruction that had been diagnosed by prenatal ultrasound. The kidneys were classified as having poor, moderate or good function based on isotope imaging at 3 months after birth. Of 9 kidneys that showed poor function 3 recovered sufficient function on pigtail drainage to justify preservation and these patients underwent pyeloplasty. Of 27 kidneys with moderate function 23 also underwent pyeloplasty and 14 of these demonstrated improvement in function postoperatively. Of the 100 kidneys in the good function group that were followed conservatively 23 underwent pyeloplasty during followup primarily because of an observed decrease in function. We propose that there is no indication for immediate pyeloplasty in infants with prenatally diagnosed hydronephrosis who demonstrate good function postnatally.

Fanconi syndrome, ichthyosis, dysmorphism, jaundice and diarrhoea--a new syndrome

We describe six infants, from consanguineous marriages, with a new syndrome comprising the Fanconi syndrome, ichthyosis, musculoskeletal abnormalities, jaundice and diarrhoea. In addition two of the infants were found to have abnormal platelet morphology--the grey platelet syndrome. No evidence of a recognised metabolic disorder was found in any of the six infants, nor did they appear to be typical of any previously described syndromes. Their progress was poor: they required high fluid and bicarbonate intakes and all died by the age of 6 months of dehydration, acidosis and sepsis.

Phaeochromocytoma--investigation and management of 10 cases

Since 1960 we have diagnosed phaeochromocytoma (paraganglioma) in 10 children. The cases include a 15 year old girl who over a three year period presented with multiple paragangliomata and an associated malignant carotid body tumour. All children were hypertensive, eight of 10 presenting with severe headaches. Diagnosis was based on finding a raised urinary vanillylmandelic acid excretion and plasma noradrenaline concentration. In addition six of eight children were hypercalcaemic with raised plasma calcitonin concentrations; plasma parathyroid hormone concentrations were high in two of seven and four out of eight children had raised plasma renin activities on presentation. No child, however, was found to have a multiple endocrine neoplasia syndrome. Despite the introduction of newer techniques for the detection of catecholamine producing tumours we found that selective arteriography and venous catecholamine sampling were superior for tumour localisation compared with ultrasound scanning, computed tomography, and metaiodo-benzyl-guanidine (MIBG) scanning.

Absence of effect of dipyridamole on renal and platelet function in diabetes mellitus

We evaluated the effect of dipyridamole (5 mg/kg/day) for 12 months on renal and platelet function in 53 children with insulin dependent diabetes mellitus (IDDM) in a prospective double blind placebo controlled trial. Urine albumin excretion (expressed as the geometric mean albumin to creatinine concentration ratio (UA/UC) was measured every three months throughout the study. At 12 months, the geometric mean UA/UC was no different in diabetic children receiving dipyridamole, 0.60 mg/mmol, when compared with those receiving placebo, 0.87 mg/mmol. Glomerular filtration rate, urinary excretion of retinol binding protein, and N-acetyl-beta-D-glucosaminidase (NAG), blood pressure, and spontaneous platelet aggregation in response to stirring whole blood did not differ between the two groups at 12 months. Subgroup analysis to include only those children with high UA/UC before entry into the study also failed to show an effect of the drug on UA/UC. Eleven children had either persistently high UA/UC (n = 8: four on dipyridamole, four on placebo) or progression to high UA/UC (n = 3: two on dipyridamole, one on placebo). These children had significantly higher urinary excretion of retinol binding protein and NAG, bigger kidneys, and higher diastolic blood pressure both before and after treatment than the remaining 42 children, whereas there was no difference in spontaneous platelet aggregation between the two groups. These observations on the associations between UA/UC and other parameters of renal function suggest that measurement of 'tubular' proteins and diastolic blood pressure as well as UA/UC may contribute to the identification of those at risk of developing nephropathy.