Mutations in ATP6N1B, encoding a new kidney vacuolar proton pump 116-kD subunit, cause recessive distal renal tubular acidosis with preserved hearing.

The multi-subunit H+-ATPase pump is present at particularly high density on the apical (luminal) surface of -intercalated cells of the cortical collecting duct of the distal nephron, where vectorial proton transport is required for urinary acidification. The complete subunit composition of the apical ATPase, however, has not been fully agreed upon. Functional failure of -intercalated cells results in a group of disorders, the distal renal tubular acidoses (dRTA), whose features include metabolic acidosis accompanied by disturbances of potassium balance, urinary calcium solubility, bone physiology and growth. Mutations in the gene encoding the B-subunit of the apical pump (ATP6B1) cause dRTA accompanied by deafness. We previously localized a gene for dRTA with preserved hearing to 7q33-34 (ref. 4). We report here the identification of this gene, ATP6N1B, which encodes an 840 amino acid novel kidney-specific isoform of ATP6N1A, the 116-kD non-catalytic accessory subunit of the proton pump. Northern-blot analysis demonstrated ATP6N1B expression in kidney but not other main organs. Immunofluorescence studies in human kidney cortex revealed that ATP6N1B localizes almost exclusively to the apical surface of -intercalated cells. We screened nine dRTA kindreds with normal audiometry that linked to the ATP6N1B locus, and identified different homozygous mutations in ATP6N1B in eight. These include nonsense, deletion and splice-site changes, all of which will truncate the protein. Our findings identify a new kidney-specific proton pump 116-kD accessory subunit that is highly expressed in proton-secreting cells in the distal nephron, and illustrate its essential role in normal vectorial acid transport into the urine by the kidney.

Mutations in the chloride channel gene, CLCNKB, cause Bartter's syndrome type III.

Analysis of patients with inherited hypokalaemic alkalosis resulting from salt-wasting has proved fertile ground for identification of essential elements of renal salt homeostasis and blood-pressure regulation. We now demonstrate linkage of this phenotype to a segment of chromosome 1 containing the gene encoding a renal chloride channel, CLCNKB. Examination of this gene reveals loss-of-function mutations that impair renal chloride reabsorption in the thick ascending limb of Henle's loop. Mutations in seventeen kindreds have been identified, and they include large deletions and nonsense and missense mutations. Some of the deletions are shown to have arisen by unequal crossing over between CLCNKB and the nearby related gene, CLCNKA. Patients who harbour CLCNKB mutations are characterized by hypokalaemic alkalosis with salt-wasting, low blood pressure, normal magnesium and hyper- or normocalciuria; they define a distinct subset of patients with Bartter's syndrome in whom nephrocalcinosis is absent. These findings demonstrate the critical role of CLCNKB in renal salt reabsorption and blood-pressure homeostasis, and demonstrate the potential role of specific CLCNKB antagonists as diuretic antihypertensive agents.

Mutations in the gene encoding B1 subunit of H+-ATPase cause renal tubular acidosis with sensorineural deafness.

H+-ATPases are ubiquitous in nature; V-ATPases pump protons against an electrochemical gradient, whereas F-ATPases reverse the process, synthesizing ATP. We demonstrate here that mutations in ATP6B1, encoding the B-subunit of the apical proton pump mediating distal nephron acid secretion, cause distal renal tubular acidosis, a condition characterized by impaired renal acid secretion resulting in metabolic acidosis. Patients with ATP6B1 mutations also have sensorineural hearing loss; consistent with this finding, we demonstrate expression of ATP6B1 in cochlea and endolymphatic sac. Our data, together with the known requirement for active proton secretion to maintain proper endolymph pH, implicate ATP6B1 in endolymph pH homeostasis and in normal auditory function. ATP6B1 is the first member of the H+-ATPase gene family in which mutations are shown to cause human disease.

Hypomorphic mutations in meckelin (MKS3/TMEM67) cause nephronophthisis with liver fibrosis (NPHP11).

BACKGROUND: Nephronophthisis (NPHP), a rare recessive cystic kidney disease, is the most frequent genetic cause of chronic renal failure in children and young adults. Mutations in nine genes (NPHP1-9) have been identified. NPHP can be associated with retinal degeneration (Senior-Løken syndrome), brainstem and cerebellar anomalies (Joubert syndrome), or liver fibrosis. METHODS: To identify a causative gene for the subset of patients with associated liver fibrosis, the authors performed a genome wide linkage search in a consanguineous family with three affected patients using 50K SNP microarrays and homozygosity mapping. RESULTS: The authors obtained a significant maximum parametric LOD (logarithm of odds) score of Z(max) = 3.72 on chromosome 8q22 and identified a homozygous missense mutation in the gene MKS3/TMEM67. When examining a worldwide cohort of 62 independent patients with NPHP and associated liver fibrosis we identified altogether four novel mutations (p.W290L, p.C615R, p.G821S, and p.G821R) in five of them. Mutations of MKS3/TMEM67, found recently in Meckel-Gruber syndrome (MKS) type 3 and Joubert syndrome (JBTS) type 6, are predominantly truncating mutations. In contrast, the mutations detected here in patients with NPHP and associated liver fibrosis are exclusively missense mutations. This suggests that they may represent hypomorphic alleles, leading to a milder phenotype compared with the more severe MKS or JBTS phenotype. Additionally, mutation analysis for MKS3/TMEM67 in 120 patients with JBTS yielded seven different (four novel) mutations in five patients, four of whom also presented with congenital liver fibrosis. CONCLUSIONS: Hypomorphic MKS3/TMEM67 mutations cause NPHP with liver fibrosis (NPHP11). This is the first report of MKS3 mutations in patients with no vermian agenesis and without neurological signs. Thus NPHP, JBTS, and MKS represent allelic disorders.

Novel ATP6V1B1 and ATP6V0A4 mutations in autosomal recessive distal renal tubular acidosis with new evidence for hearing loss.

Autosomal recessive distal renal tubular acidosis (rdRTA) is characterised by severe hyperchloraemic metabolic acidosis in childhood, hypokalaemia, decreased urinary calcium solubility, and impaired bone physiology and growth. Two types of rdRTA have been differentiated by the presence or absence of sensorineural hearing loss, but appear otherwise clinically similar. Recently, we identified mutations in genes encoding two different subunits of the renal alpha-intercalated cell's apical H(+)-ATPase that cause rdRTA. Defects in the B1 subunit gene ATP6V1B1, and the a4 subunit gene ATP6V0A4, cause rdRTA with deafness and with preserved hearing, respectively. We have investigated 26 new rdRTA kindreds, of which 23 are consanguineous. Linkage analysis of seven novel SNPs and five polymorphic markers in, and tightly linked to, ATP6V1B1 and ATP6V0A4 suggested that four families do not link to either locus, providing strong evidence for additional genetic heterogeneity. In ATP6V1B1, one novel and five previously reported mutations were found in 10 kindreds. In 12 ATP6V0A4 kindreds, seven of 10 mutations were novel. A further nine novel ATP6V0A4 mutations were found in "sporadic" cases. The previously reported association between ATP6V1B1 defects and severe hearing loss in childhood was maintained. However, several patients with ATP6V0A4 mutations have developed hearing loss, usually in young adulthood. We show here that ATP6V0A4 is expressed within the human inner ear. These findings provide further evidence for genetic heterogeneity in rdRTA, extend the spectrum of disease causing mutations in ATP6V1B1 and ATP6V0A4, and show ATP6V0A4 expression within the cochlea for the first time.

T-lymphocyte populations, cytokines and other growth factors in serum and urine of children with idiopathic nephrotic syndrome.

The T-cell defect present in the idiopathic nephrotic syndrome (INS) was investigated in 29 steroid-sensitive and 14 steroid-resistant children aged 2-19 years. Nine different lymphocyte subpopulations and 15 cytokines, receptors and other growth factors were measured in blood, and some also in urine. In steroid-sensitive patients we found a decreased ratio of helper/inducer cells (CD4+) versus suppressor/cytotoxic cells (CD8+) in relapse and remission, and an increased proportion of natural killer cells (CD16+) during relapse vs long-term remission, as a sign of an elevated cytotoxic potential. Among the serum cytokines mainly produced by monocytes/macrophages interleukin (IL)-8 levels were decreased in steroid-sensitive patients vs controls, with normal levels observed for IL-1 alpha, IL-1 beta, IL-1RA and tumor necrosis factor (TNF-alpha). IL-2 was the only cytokine produced by TH1 cells which was significantly increased during relapse vs long-term remission. We also observed a trend for elevated levels of sIL-2R and IFN-gamma. Serum levels of cytokines derived from TH2 cells were variable. IL-4 was decreased during relapse but increased in patients with long-term remission. SIL-6 receptors were increased during relapse. Finally we observed decreased serum levels of IL-3 and of the adhesion molecule ICAM-1 in active INS. Patients with steroid-resistant INS exhibited similar changes of T-cell populations and cytokines as steroid-sensitive patients; their CD4+/CD8+ ratio was reduced to the same degree and sIL-2R levels were even higher than in steroid-sensitive patients. In conclusion this study indicates that active INS is associated with an increased number of cytotoxic cells in the blood and an elevated TH1 cytokine production. Long-term remission appears to be related to increased TH2 cytokine production downregulating TH1 cytokines and cytotoxic cells. Our data give evidence that different immune mechanisms are involved in the pathogenesis of INS.

Pharmacokinetics of amikacin, netilmicin and tobramycin in children with chronic renal failure.

The single-dose pharmacokinetics of amikacin, netilmicin and tobramycin administered intramuscularly at doses of 7.5 mg/kg amikacin, 2.5 mg/kg netilmicin or 3 mg/kg tobramycin were studied in 30 children with chronic renal failure. Serum amikacin, netilmicin and tobramycin levels were measured by a radioimmunoassay method. The correlation between serum creatinine levels and the half-life of the antibiotics was found to be statistically significant. There were interpatient differences in serum aminoglycoside levels among those with the same serum creatinine levels. Thus, monitoring of serum creatinine and aminoglycoside levels is recommended, especially for those with renal failure, in order to maintain an optimal dosage between toxic and noneffective serum aminoglycoside levels.

Follow-up results of synthetic vascular grafts in children undergoing hemodialysis.

Polytetrafluoroethylene (PTFE) grafts were inserted in the thigh of 14 children (7 boys and 7 girls, age 12 +/- 1.8 years) who were undergoing chronic hemodialysis for endstage renal disease. Removal of grafts was necessary in three patients within three months of implantation. In a fourth case it was indicated in the fifteenth month. In two cases thrombectomy was necessary. Echocardiography was performed in 10 patients before and three and 12 months after surgery. Cardiac performance followed by echocardiography did not change after one year. After two years the survival of grafts was 71%. It appears that synthetic grafts offer advantages for pediatric hemodialysis patients with arteriovenous fistula failure. On the other hand, this technique entails serious risks.

What has changed in pediatric kidney transplantation in Turkey? Experience of an evolving center.

INTRODUCTION: Reluctance to perform kidney transplantations on children is an ongoing problem in Turkey. Moreover, urological pathologies still constitute the largest portion of the underlying etiologies in chronic renal failure patients. Herein, we retrospective analyzed the data acquired from our pediatric renal transplantation patients and reviewed the registry of dialysis and transplantation data prepared by the Turkish Society of Nephrology. MATERIAL AND METHODS: Forty-six living donor kidney transplantations were performed in children between 2008 and 2012. Seventeen of 46 (37%) transplantations were preemptive. The mean age at operation time was 10.8 ± 5 years. The mean patient weight was 31.3 ± 15.8 kg (range, 9.4 to 66.4 kg). A detailed urologic evaluation was performed for every child with an underlying lower urinary tract disease. One enterocystoplasty and 2 ureterocystoplasties were performed for augmentation of the bladder, simultaneously. RESULTS: One-year death-censored graft survival and patient survival rates were 100% and 97.8%, respectively. The mean serum creatinine level was 0.86 ± 0.32 mg/dL (range, 0.3 to 1.8 mg/dL). None of the patients had vascular complications or acute tubular necrosis. One patient suffered graft-versus-host disease during the second month after renal transplantation and died with a functioning graft. In one patient with massive proteinuria detected after transplantation, recurrence of primary disease (focal segmental glomerulosclerosis) was considered and the patient was treated successfully with plasmapheresis. One child had an acute cellular rejection and was administered pulse steroid treatment. CONCLUSION: Although challenging, all patients in all pediatric age groups can successfully be operated and managed. With careful surgical technique, close postoperative follow-up, and efforts by the experienced and respectful surgical teams in this country, we could change the negative trends toward perform kidney transplantation in the Turkish pediatric population.

Circumcision for the prevention of significant bacteriuria in boys.

The aim of this study was to determine whether circumcision affects significant bacteriuria in boys. During a 60-month prospective study, 100 boys with microbiologically confirmed symptomatic urinary tract infection (UTI) were evaluated. Twelve patients with abnormal ultrasonography findings were excluded from the study. Eighteen of the boys had not been circumcised due to parental choice. The remaining 70 boys with normal renal ultrasonography were randomly allocated into two groups. In the first group 35 boys ranging in age from 6 months to 10 years (mean 33.2+/-30.9 months) were observed for 6 months and urinary cultures were taken monthly. When they had a positive urine culture (with or without any symptoms), they received antibiotic treatment. After 6 months they were circumcised and then observed for another 6-month period. Group 2 comprised 35 boys aged from 3 months to 9 years (mean 29.1+/-36.7 months). They were circumcised immediately after the first UTI and were followed for 6 months. Urine samples were obtained by the bag technique in infants and by the mid-stream technique in older patients. In the uncircumcised group, the rate of significant bacteriuria per patient did not change in two 6-month follow-up periods (3.46+/-0.91 and 3.33+/-0.97 episodes). In group 1, the rate of positive urine cultures dropped from 3.57+/-1.11 to 0.14+/-0.35 episodes after circumcision (P<0.001). In the second group, the rate of significant bacteriuria was 0.17+/-0.38 episodes after circumcision. Among the uncircumcised patients, symptomatic UTI was observed in 6 cases (3 cases in the first period of group 1, 1 case in the first and 2 cases in the second period of the uncircumcised group), whereas after circumcision no patient had symptomatic UTI. The mean age at circumcision was 42.7+/-28.4 months. No complication due to circumcision occurred in any patient. UTI may also occur in boys after the 1st year of life. The present study indicated that circumcision in boys decreases the rate of positive urine cultures. Therefore circumcision could be considered as a part of UTI therapy.

The effects of vaccination with inactivated uropathogenic bacteria in recurrent urinary tract infections of children.

Secretory IgA (sIgA) is an important parameter in the predisposition to recurrent urinary tract infection (UTI). We investigated whether sIgA and frequency of UTI could be positively influenced by intramuscular vaccination with inactivated uropathogenic bacteria (Solco-Urovac). Ten otherwise healthy girls aged from 5 to 11 years (mean 9 1.7 years) with recurrent UTI were immunized with Solco-Urovac by i.m. injections three times at weekly intervals. A booster injection was given after 6 months. Urinary sIgA secretory component (SC) concentration was determined by radial immunodiffusion assay. Ten other age-matched girls with UTI were not immunized. Immunization therapy caused a significant reduction in the frequency of infection and an increase in urinary sIgA SC, while in the nonvaccinated group the values remained constant.

Pulse methylprednisolone therapy in children with membranoproliferative glomerulonephritis.

The effects of pulse methylprednisolone (PM) therapy were studied in 15 patients (aged 3-14 years) with biopsy proven membranoproliferative glomerulonephritis (MPGN). Patients were treated with intravenous PM 30 mg/kg (max 1 g) given over 30 min every other day for a mean of 9.8 days (3-15 days). Oral prednisolone therapy was continued at a dose of 1 mg/kg/24 h for 1 month and subsequently tapered off the following month. Eight patients had hematuria and six had medically controlled hypertension. Serum C3 levels were low in 11 patients and all of the patients had proteinuria. Following PM therapy proteinuria was significantly reduced from 2602.9 +/- 1852.5 mg/24 h to 1871.2 +/- 2090.8 mg/24 h (P < 0.05) and at final evaluation, proteinuria was 774.33 +/- 1225.67 mg/24 h which was significantly lower than pre- and post-PM therapy values (P < 0.05). Serum creatinine levels were high in five patients before PM therapy and remained high in one of the patients who progressed to end-stage renal failure. After PM therapy, high serum creatinine levels normalized in three patients and was reduced, but still above normal, in one. One patient, with initially normal serum creatinine, had elevated levels afterwards. Nine of the patients were considered responsive and six non-responsive according to our tentatively defined criteria. Mean follow-up period was 27.4 +/- 24.1 months (6-84 months). Three patients were lost for follow-up, and 12 were re-evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)

[Disorders of kidney function in asphyxic newborn infants]. / Die Nierenfunktionsstörungen asphyktischer Neugeborener.

In this study it was aimed to investigate the renal function disturbances at an early stage of term newborn babies with perinatal asphyxia. 18 term newborn babies with the diagnosis of perinatal asphyxia were followed in the first 3 days of their lives, and various laboratory tests were applied to evaluate the renal functions. The results were compared with 10 healthy newborn who were chosen as a control group. The renal functions glomerular filtration rate (GFR) and fractional sodium excretion (FENa) were found significantly impaired up to 60% in the asphyctic babies especially those whose clinical presentation was expected to be severe.

A case of an enterorenal fistula and pyelonephritis with air in the renal pelvis.

We report on a 10-year-old boy with recurrent urinary tract infection. Renal ultrasound demonstrated the presence of air in the collecting system of the right kidney. The patient was examined radiologically and an enterorenal fistula was diagnosed. The case serves as a reminder that, although entero-renal fistulas are rare, they should be included in the differential diagnosis of recurrent urinary tract infections, especially if air is observed in the collecting system.

Etiology of chronic renal failure in Turkish children.

The etiology of chronic renal failure (CRF) was studied in 459 Turkish children (205 girls, 254 boys) for the period January 1979-December 1993. Their mean age at onset of CRF was 9.5 +/- 4.2 years (range 1-16 years); CRF was defined as a glomerular filtration rate (GFR) below 50 ml/min per 1.73 m2 for at least 6 months. When a GFR determination was not available, the serum creatinine concentration was used: greater than 1 mg/dl for children aged 1-3 years, greater than 1.5 mg/dl for those 3-10 years and greater than 2 mg/dl for those 10-16 years. Primary renal disorders were as follows: reflux nephropathy 32.4% glomerular diseases 22.2%, hereditary renal disorders 11.4%, amyloidosis 10.6%, urinary stones 8% and other renal disorders 15.4%. Twenty-three cases of reflux nephropathy (15.4%) were associated with neural tube defects (NTD) and 20 (13.4%) were caused by infravesical obstruction. CRF caused vesicoureteral reflux associated with NTD and amyloidosis are more frequent in our series compared with west European and Nordic countries.

Causes of increased renal medullary echogenicity in Turkish children.

The primary disorders of 50 children with increased renal medullary echogenicity on renal ultrasound were studied; 28 girls and 22 boys aged from 1 month to 16 years were classified into four groups based on underlying disease and ultrasound findings. Group 1 was composed of 17 patients with distal renal tubular acidosis (34%); intense echoes throughout the pyramid were predominant. Group 2 consisted of 14 patients with vitamin D toxicity (28%) and an intense echogenic rim around the pyramids. Group 3 included 10 patients with different types of tubulopathies. A slight hyperechogenic rim around the sides and tip of the medullary pyramids was detected. Group 4 was made up of 9 patients with rare underlying conditions. Abdominal X-rays detected medullary calcinosis in only 12 (24%) of the total 50 patients. Ultrasonography appears to be an important tool in the early diagnosis of increased renal medullary echogenicity and medullary nephrocalcinosis.

Hemostatic problems and thromboembolic complications in nephrotic children.

A hypercoagulable state and the risk of thromboembolism in both arterial and venous circulation is a relatively frequent and serious feature of nephrotic syndrome (NS) in children and adults. The aim of this study was to evaluate the coagulation states of children with NS before and after corticosteroid (CS) therapy and to compare the results with a healthy control group. The first group consisted of 49 nephrotic children (30 boys and 19 girls) with a mean age of 6. 5+/-4.9 years (range 1-16 years). The control group included 17 healthy children (9 boys and 8 girls). At the time of admission, all patients were evaluated for the presence of clinical thromboembolism, hematological and biochemical indicators of a hypercoagulative state, and renal disease. This was repeated after CS treatment. Deep vein thrombosis was observed in 2 nephrotic patients who had very low plasma antithrombin III (AT III) levels and fibrinogen levels above 750 mg/dl. Thus, the prevalence of thromboembolism was 4% in our pediatric nephrotic population. The mean AT III level of the study group was 68.2+/-23.4% at the onset of the disease, which was significantly lower than the level of the control group (84.0+/-7. 6%). Plasma AT III levels increased to 74.4+/-15.3% after CS treatment, which correlated with the serum albumin levels. However, there was no correlation with urinary protein excretion. Protein C levels were higher than controls during all stages of the disease in both steroid-responsive and -unresponsive patients. The mean protein S level was similar in both groups. Plasma fibrinogen and cholesterol levels were significantly higher in the study group but decreased to within normal limits with remission. Our study suggests that thromboembolic complications are not infrequent in children with NS, and may be related to low plasma AT III and albumin and high fibrinogen and cholesterol levels.

Efficacy of captopril treatment in children with steroid-resistant nephrotic syndrome.

We studied the efficacy of captopril, an angiotensin-converting enzyme inhibitor in treating persistent moderate or severe proteinuria in children with various glomerular diseases other than minimal-change nephrotic syndrome. Captopril was administered for 3 months to 15 normotensive and nonazotemic or mildly azotemic patients (12 boys, 3 girls) in whom corticosteroid and cytotoxic treatment had failed to induce remission. Urinary protein excretion decreased from 2873.14 +/- 1937.50 (mean +/- s.e.m.) to 1684.71 +/- 1463.13 mg/day (P < 0.05). The reduction in proteinuria was not related to a significant fall in systemic blood pressure or a change in renal function. Serum albumin did not rise and side effects due to captopril were not observed. We concluded that, in the short term, captopril can be used safely and effectively for decreasing the proteinuria of nephrotic children unresponsive to conventional therapy.

Coexistence of VATER association and recurrent urolithiasis: a case report.

VATER association is diagnosed by the combined presence of at least three of the following features: vertebral anomalies, anal atresia, tracheo-esophageal fistula and/or esophageal atresia, radial ray anomalies, and renal anomalies (53%). Urolithiasis has not been reported in this syndrome. A 4-month old girl presented because of irritability, and the presence of stones in the diapers. Physical examination revealed anal atresia for which colostomy was performed in the newborn period. The diagnosis of VATER association was established by the additional findings of hemivertebrae, sacral dysgenesis, and horseshoe kidney which was partly non-functional. Urinary pH was repeatedly below 6. An excreted stone consisted of pure uric acid. Metabolic investigations detected no specific pathology in purine metabolism. Urolithiasis did not recur after reconstructive anal and anorecto-vaginoplasty, implying that it was a consequence of colostomy and/or of the underlying renal anomaly. We suggest that after colostomy patients with VATER association should be followed for possible urate stones, e.g. by regular screening of urinary pH.

Arterial changes in paediatric haemodialysis patients undergoing renal transplantation.

BACKGROUND: The relationship between primary renal disease and arterial wall changes in paediatric haemodialysis patients has been little studied. The aim of the present work was to determine the influence of primary renal disease on arterial wall pathology in uraemic paediatric patients. METHODS: Twelve paediatric haemodialysis patients (seven girls, five boys) aged 11-17 years were included in the study. The primary renal diseases were urinary malformations in six patients (uropathy group) and acquired glomerular diseases (glomerulopathy group) in six patients. Age, sex distribution, duration of chronic renal failure, duration of haemodialysis, blood pressure, serum glucose, triglycerides, cholesterol, fibrinogen, calcium, phosphorus and parathyroid hormone levels were compared. Internal iliac artery samples were obtained at the time of related-donor renal transplantation. Artery samples were fixed in formaldehyde and sections were stained separately with haematoxylin and eosin, Orcein, Verhoef-van Gieson, and Masson trichrome. RESULTS: Five arteries had fibrous or fibroelastic intimal thickening, medial mucoid ground substance and disruption of the internal elastic lamella. Two of these had microcalcification in the intimal layer; another two demonstrated atheromatous plaques; the remaining five were normal. These pathological changes were found in the arteries of all six patients with uropathy, whereas of the six patients with glomerulopathy only one had arterial changes (P<0.001). The duration of chronic renal failure was 4.8+/-1.9 years in the uropathy group and 2.2+/-1.2 in the glomerulopathy group (P<0.05). The two groups were comparable in terms of serum glucose, triglycerides, cholesterol, fibrinogen, calcium, and parathyroid hormone levels, presence of hypertension, sex distribution, and duration of haemodialysis. Plasma phosphorus and the calcium x phosphate product were higher in the uropathy group than in the glomerulopathy group (P<0.05). CONCLUSIONS: This study demonstrated that pathological changes are common in the arteries of uraemic paediatric patients, and that calcification and atherosclerosis are integral to this disease process. In our study, these alterations were more common in the patients with uropathy. We speculate that the patients with uropathy are more prone to these alterations due to slower progression and a longer duration of renal insufficiency.