Renal polyamine excretion, tubular amino acid reabsorption and molecular genetics in cystinuria.

Cystinuria is an autosomal recessive disorder of the tubular and intestinal resorption of cystine, ornithine. lysine and arginine leading to nephrolithiasis. Three cystinuria types can be distinguished by the mode of inheritance (true recessive or intermediate) and by the pattern of the intestinal amino acid transport. In the present study phenotypes were assessed by the urinary excretion of amino acids related to creatinine, the percentage tubular amino acid reabsorption and the urinary excretion of polyamines as a possible indicator of the intestinal transport defect. However, our thorough phenotyping did not reveal more than two cystinuria types. Genotypes were examined in linkage analyses and single-strand conformation polymorphism-based mutation identification. The SLC3A1 mutations M467T and T216M were disease causing in our homozygous patients of type I cystinuria. We can show the association of type I cystinuria with SLC3A1 and of non-type I cystinuria with a yet unidentified gene on chromosome 19q13.1. Our phenotype and genotype analyses provide evidence for only two types of cystinuria in the investigated patient cohort.

Distal myopathy in nephropathic cystinosis.

In long-standing nephropathic cystinosis complications are observed in various organs. Distal myopathy was first described in detail in 1994. The prevalence was calculated to be 24%. We studied seven patients with nephropathic cystinosis with neurophysiological techniques. Only two patients complained of a distal muscle weakness but all showed signs of myopathy on electromyography, which was more pronounced in the distal muscles. Motor and sensory nerve conduction parameters were within normal ranges. One patient with the juvenile form of nephropathic cystinosis also had myopathy. We conclude that distal myopathy can be detected in nephropathic cystinosis even in the absence of clinically overt muscle weakness. Cystine-depleting therapy with cysteamine is recommended for all patients with cystinosis, even after renal transplantation, and the effect on the myopathy should be studied.

Progressive familial intrahepatic cholestasis: partial biliary diversion normalizes serum lipids and improves growth in noncirrhotic patients.

OBJECTIVES: Progressive familial intrahepatic cholestasis (PFIC) usually presents with pruritus, jaundice, hepatomegaly, and growth failure. A group of PFIC is recognized by marked elevation of total serum bile acids, decreased serum apolipoprotein A-1, and high-density lipoprotein, but normal gamma-glutamyltranspeptidase and cholesterol. Although medical therapy generally fails, partial external biliary diversion (DIV) has been used with promising results for cholestasis. However, little has been reported of its effect on linear growth, synthetic liver function, and lipid metabolism. METHODS: DIV was performed on six noncirrhotic children with PFIC, all suffering from severe pruritus and cholestasis, refractory to medical treatment. Stature was below -1 (median, -2.3) standard deviation score (SDS) for height in all cases. All patients had markedly enhanced bile acids (307 +/- 72 microl/L), markedly decreased high-density lipoprotein (20 +/- 7 mg/dl), and apolipoprotein A-1 (58 +/- 37 mg/dl), but normal gamma-glutamyltranspeptidase and cholesterol. In addition, cholinesterase activity, monoethylglycinexylidide test, and Fischer's ratio indicated a significantly reduced synthetic liver function in all children but the youngest. RESULTS: After DIV, all patients were consistently relieved of pruritus, and experienced normalization of all liver function tests, including cholinesterase activity, monoethylglycinexylidide test, and Fischer's ratio, as well as the serum lipid profile within 1 yr. In addition, a marked catch-up growth (median, +/- 1.3 SDS) was evident after 1 yr in all cases. CONCLUSIONS: This report shows an excellent result of DIV in noncirrhotic PFIC patients and compares favorably with other reports. All patients experienced complete remission, including normalization of synthetic liver function and lipid metabolism. For the first time we have shown that DIV can also be associated with an accelerated growth in these patients.

Cystatin C and creatinine after successful kidney transplantation in children.

BACKGROUND: Serum creatinine is commonly used for the monitoring of allograft function following renal transplantation (RTX). Due to lower muscle mass, creatinine production rate is reduced in children, thus decreasing its sensitivity for the detection of allograft dysfunction. In children, the serum concentration of cystatin C, a low molecular weight protein of 13.3 kDa, reflects glomerular filtration rate independent of age, height and body composition. We, therefore, sought to assess the potential of cystatin C as a marker of allograft function in children. METHODS: Cystatin C and creatinine were measured in parallel at least daily in 24 children (14 boys, 10 girls; mean age 10.5+/-5.1 years) during hospitalization after successful RTX. Cystatin was determined immunoturbidimetrically, creatinine enzymatically. RESULTS: Within one hour after RTX, cystatin C (mean+/-SE) almost halved from 6.69+/-0.45 mg/l to 3.69+/-0.38 mg/l while creatinine declined from 862 +/-65.4 to 633+/-62.9 micromol/l. Following a nadir of 1.82+/-0.18 mg/l on day 2, there was a secondary increase in cystatin C concentrations to 2.69+/-0.35 mg/l on day 10. Creatinine concentrations continued to decline until day 9 reaching 80.5+/-13.1 micromol/l. Day-to-day variation at steady-state was comparable. In the course of 9 acute rejection episodes, both parameters rose in parallel, the increase in creatinine concentration being much greater. CONCLUSION: Cystatin C was an early indicator of allograft function following successful RTX in children. It did not prove superior to creatinine for the recognition of acute allograft dysfunction, however.

Kidney transplanted children come of age.

BACKGROUND: The aim of renal replacement therapy in children is to restore their potential for normal growth and development in order to reach mature adulthood. Because pediatric kidney transplantation started in the late 1960s, it is now possible to document the progress and outcome of these patients from transplantation in childhood to survival into adulthood. METHODS: In this single-center study, all 150 children born before December 1977 and having received a kidney transplant between 1970 and 1993 were selected for long-term follow-up. The mean age at transplantation was 12.1 years (range 3.2 to 16.7), and the mean follow-up was 13.1 years (range 2.0 to 25.0). In December 1995, 124 grown-up patients with a mean age of 25.4 years (range 18.4 to 40.3) were alive, 89 with a functioning graft. Fifty had the first graft functioning longer than 10 years. The fate of all patients was traced, and those living were analyzed in regard to their somatic and socioeconomic states. RESULTS: The actuarial 25-year survival rate for the patients was 81%, and for the first graft it was 31%. The best graft survival rates were observed after living related donation, preemptive transplantation, and immunosuppression with cyclosporine. The latter benefit, however, vanished after eight years. The mean creatinine clearance declined over the years from 76 to 45 ml/min/1.73 m2, and the incidence of hypertension increased to more than 80% of the patients. Malignancies occurred in 2.6%. Final height was stunted in 44% of noncystinotic patients, whereas all patients with cystinosis were extremely growth retarded. Twenty-seven percent suffered from additional disabilities. A majority of adult patients were rehabilitated in regard to education and socioeconomic status, and 14% were unemployed. CONCLUSIONS: The results indicate that renal transplantation in children leads to a high degree of rehabilitation in adulthood. The life of a kidney transplant, however, is limited, which points out the need for more specific immunosuppression with fewer side-effects in order to reach the goal of lifelong graft function.

Does tacrolimus cause more severe anemia than cyclosporine A in children after renal transplantation?

Initial reports indicated the possibility of severe anemia associated with tacrolimus (TC) therapy. We investigated the degree of anemia under TC treatment in comparison to cyclosporine A (CsA) treatment in children after renal transplantation. A cross-sectional analysis of 95 children successfully transplanted for at least 3 months was performed. Eighty-five children received CsA and 10 TC. TC-treated patients were compared with CsA-treated patients who were matched according to age, gender, creatinine clearance, and time after transplantation. No patient received additional therapy with mycophenolate mofetil or azathioprine. The creatinine clearance of the whole group of transplanted children was 58 ml/min per 1.73 m2. The patients within the matched-pair analysis had a lower creatinine clearance (TC 46 and CsA 48 ml/min per 1.73 m2). The hemoglobin was 10.3 g/dl for the TC-treated children and 10.4 g/dl among the CsA-treated patients. Numerically, EPO was higher and iron lower in the TC group than in the CsA group. Among children with functioning renal grafts, a correlation exists between Hb and creatinine clearance. A significant difference in the degree of anemia between TC- and CsA-treated children could not be found.

Cystatin C--a new marker of glomerular filtration rate in children independent of age and height.

OBJECTIVES: Serum creatinine is the most common endogenous marker of renal function. The proportionality between creatinine production and muscle mass requires adjustment for height and body composition. The low molecular weight protein cystatin C is produced by all nucleated cells and eliminated by glomerular filtration. Therefore, cystatin C was studied as an alternative marker of glomerular filtration rate (GFR) in children. METHODS: Cystatin C and creatinine were measured in sera from inulin clearance (CIn) examinations performed in 184 children aged 0.24 to 17.96 years. CIn ranged from 7 to 209 mL/min/1.73 m (median, 77). RESULTS: The reciprocal of cystatin C correlated better with CIn (r = 0.88) than the reciprocal of creatinine (r = 0.72). Stepwise regression analysis identified no covariates for the correlation between cystatin C and CIn, whereas height was a covariate for creatinine. Using an estimate of GFR from serum creatinine and height, correlation with CIn was similar to cystatin C, but female gender and dystrophy were associated with an overestimation of GFR. Diagnostic accuracy in the identification of reduced GFR measured as area under the receiver-operating characteristic plot was 0.970 +/- 0.135 (mean +/- SE) for cystatin C and 0.894 +/- 0.131 for creatinine (NS). A cutoff cystatin C concentration of 1.39 mg/L had 90% sensitivity and 86% specificity for detecting abnormal GFR. CONCLUSION: Unlike creatinine, serum cystatin C reflects renal function in children independent of age, gender, height, and body composition.

End-stage renal failure in children younger than 6 years: renal transplantation is the therapy of choice.

UNLABELLED: Between 1975 and 1994, 46 children under 6 years of age received a total of 52 renal transplants. Obstructive uropathy and dysplasia accounted for most causes of terminal renal failure (17 and 12 cases respectively). Four patients required a second, 1 patient a third transplantation. Cadaveric organs were used on 33 occasions; 19 patients received a living-related donor kidney. Immunosuppression was performed with azathioprine in 5, with cyclosporine A in 21 and combined azathioprine/cyclosporine therapy in 20 cases. After 1 year, graft survival was 81%, and after 5 years 78%. Creatinine clearance declined slightly between 1 and 5 years from 69 to 56 ml/min per 1.73 m2. Main causes of graft failure were thrombotic complications in 6 cases and death with functioning graft in 5 cases. Graft thrombosis occurred only in grafts from young donors under the age of 7 years and after vascular anastomosis to the iliac vessels. Only two transplants were lost in rejection episodes. Patient survival was 94% after 1 and 90% after 5 years. Two patients died due to septiacemia, 1 died of a ruptured aortic aneurysm, 1 of cerebral ischaemia and 1 suddenly of unknown cause. Patient and graft survival was not different compared with 204 patients aged 6-16 years who received a renal transplantation during the same time period at our institution. After transplantation the patients receiving cyclosporine A showed a marked catch-up growth in the 1st year. The median standard deviation score (SDS) of body length improved from -2.63 to -1.39 standard deviations. CONCLUSION: Renal transplantation is the treatment of choice in end-stage renal failure in children under 6 years.

Recurrence of renal disease after kidney transplantation in children: 24 years of experience in a single center.

The aim of this study was to assess the frequency and clinical implications of a recurrence of the original renal disease in children after kidney transplantation. Thus, the records of patients with immunological and metabolic diseases transplanted between 1970 and 1994 were retrospectively analyzed. There were 113 renal transplantations in 99 patients, who had the following original diseases: focal segmental glomerulosclerosis (FSGS), membrano-proliferative glomerulonephritis type I and type II (MPGN I, II), Henoch-Schoenlein nephritis, IgA-nephropathy, hemolytic uremic syndrome (HUS) and hyperoxaluria type I (PH I) and other rare diseases. Recurrences were observed in FSGS, MPGN II, HUS and PH I but not in the other diseases. In FSGS, the recurrence rate was 20% with graft failure in 5 of 6 grafts. No specific risk factors for recurrent FSGS could be determined. In MPGN II, the recurrence was 60% but the loss of grafts occurred at the same rate as in the non-recurrence group. In HUS, recurrence was seen in 4 out of 24 renal grafts (16.6%) with subsequent graft loss in all cases. All cases had suffered from an atypical HUS. PH I recurred in 4 of 5 allografts with graft loss in all patients. The remaining graft was transplanted after a liver transplantation and graft function was well preserved for 4 years. We confirm that the risk of recurrence with loss of the graft is high in a certain group of renal diseases. In these the indication for transplantation, particularly with living related donor kidneys, needs special evaluation. A better understanding of the pathomechanism of the diseases should lead to prevention of recurrence, as in PH I in which a liver transplant is now the primary option.

Reference values for cystatin C serum concentrations in children.

Cystatin C, a low molecular weight protein, is a new endogenous marker of renal function whose serum concentration correlates better with glomerular filtration rate than creatinine. The aim of the present study was to define a reference interval for cystatin C concentrations in children. Cystatin C was measured by an immunoturbidimetric assay in sera obtained from 258 children (93 girls, 165 boys, median age 6.29 years, range 1 day to 18 years) without evidence of kidney disease. The reference interval was calculated non-parametrically using the 2.5th and 97.5th percentiles. For comparison, creatinine was measured in the same samples. The cystatin C concentration was highest on the first days of life (range 1.64-2.59 mg/l) with a rapid decrease during the first 4 months. Beyond the 1st year, the cystatin C concentration was constant, with a reference interval of 0.7-1.38 mg/l. In contrast, serum creatinine concentrations steadily increased with age until adulthood. Compared with creatinine, cystatin C facilitates the recognition of abnormal renal function in children as its reference range is constant beyond the 1st year of life. The higher levels of cystatin C in the 1st year of life probably reflect the low glomerular filtration rate of neonates and infants.

Etiologic classification of severe hypospadias: implications for prognosis and management.

OBJECTIVE: Classification of severe hypospadias employing a broad array of diagnostic tools. Standardization of a diagnostic approach to children with hypospadias. Indentification of patients at risk of having malignancies and endocrine problems. DESIGN: Retrospective analysis of patients in a single-center study. SUBJECTS: Thirty-three patients with severe (scrotal or penoscrotal) hypospadias, aged 1 to 18 years. METHODS: Clinical assessment, ultrasonography, karyotyping, endocrine evaluation including adrenal steroid concentrations, sex hormone-binding globulin test for androgen sensitivity, human chorionic gonadotropin stimulation with determination of testosterone and dihydrotestosterone concentrations to exclude 5 alpha-reductase deficiency, and molecular genetic analysis of the androgen receptor gene and the 5 alpha-reductase gene. RESULTS: In 12 patients the cause was clarified. Diagnoses included Drash syndrome with Wilms tumor in infancy (3 patients), partial androgen insensitivity resulting from androgen receptor mutations (2), true hermaphroditism (2), chromosomal aberration (1), deficiency of antimüllerian hormone (1), gonadal dysgenesis (1), partial 5 alpha-reductase deficiency caused by a novel point mutation (1), and XX-male syndrome (1). Twelve patients had associated findings such as cardiac malformations (3 patients), rectal atresia (1), dilation of urinary tract (2), cystinuria (1), and others. CONCLUSIONS: Patients with severe hypospadias should be submitted to a standardized set of diagnostic procedures in infancy. A stepwise diagnostic study avoids unnecessary, invasive, and expensive testing. A high proportion of classified causes can be expected. Patients at risk of having malignancies or hormonal disorders must remain under close surveillance.

Response to diphtheria and tetanus booster vaccination in pediatric renal transplant recipients.

BACKGROUND: Although inactivated vaccines are recommended for immunocompromized patients, efficacy and safety of diphtheria and tetanus immunization in renal transplant recipients have received little attention so far. The aim of the study was to investigate the response to a standard diphtheria and tetanus booster vaccination in pediatric renal transplant recipients. METHODS: Forty-two children, median age 13.2 years (range, 7.8-18.9 years) with complete primary immunization 9.2 years (0.9-15.4 years) before transplantation were enrolled. Immunosuppression consisted of cyclosporine plus prednisolone in 15 (36%), cyclosporine, azathioprine, and prednisolone in 24 (57%), and tacrolimus plus prednisolone in 3 (7%). Antibodies were measured by enzyme-linked immunosorbent assay before and 1, 6, and 12 months after vaccination. RESULTS: Before vaccination, protective antibody concentrations exceeding 0.1 IU/ml against diphtheria were found in 16 children (38%). Thirty-eight (90%) had protective antibody concentrations against tetanus. After booster immunization, the protection rate against diphtheria rose to 95% at 1 month with a decline to 93% at 6 and 76% at 12 months. Protection against tetanus was complete after vaccination and persisted over the observation. Antibody concentrations were comparable to those reported for healthy children. Statistical analysis showed no influence of allograft function, immunosuppressive regimen, previous cytotoxic therapy, or time between primary immunization and end-stage renal failure on antibody response. Immunization was well tolerated and kidney function remained unaffected in patients with stable allograft function. CONCLUSIONS: Diphtheria and tetanus vaccination can be performed effectively and safely in renal transplant recipients as generally recommended.

Pharmacokinetics of cyclosporine in pediatric long-term liver transplant recipients converted from Sandimmun to Neoral.

Absorption of cyclosporin from the microemulsion formulation Neoral is less variable than from Sandimmun. Because of a lack of data in pediatric liver transplant recipients, the pharmacokinetic profiles with Sandimmun and Neoral were compared in a conversion study. Thirty-eight children with stable graft function were converted 2-12.3 years post-transplant at a 1:1 ratio. The trough-level (Cmin) with Neoral was 123 +/- 39 ng/ml versus 134 +/- 29 ng/ml with Sandimmun (P = NS), the area under the time-concentration curve (AUC) was 3325 +/- 1125 ng.h/ml versus 2423 +/- 846 ng.h/ml (P < 0.001), the peak concentration (Cmax) was 650 +/- 280 ng/ml versus 337 +/- 142 ng/ ml (P < 0.001), and the median time to Cmax was 2 h (range 0.5-3 h) versus 4 h (range 1-8 h; P < 0.05). The weak correlation between Cmin and AUC with Sandimmun (r = 0.5; P = NS) was improved by using Neoral (r = 0.7; P < 0.001). The best predictor of AUC was the 2-h concentration (C2h) of Neoral (r = 0.9; P < 0.001). Increased absorption and a more predictable pharmacokinetic profile with Neoral permit safer therapeutic monitoring in children. The exclusive measurement of Neoral-C2h allows one to estimate drug exposure with high precision (> 90%).

Liver transplantation in children with chronic end stage liver disease: factors influencing survival after transplantation.

To identify pretransplant factors that are influencing survival after orthotopic liver transplantation a Cox proportional hazards regression model was applied to 118 children with chronic terminal liver failure transplanted at Medical School Hannover during the period of 1978 to 1994. The response variable was survival, as covariates a total of 19 pretransplant variables were entered--i.e. age, diagnosis (biliary cirrhosis, metabolic cirrhosis, postnecrotic cirrhosis, cryptogenetic cirrhosis) sex, laparotomy prior to OLT, height, weight, standard deviation scores for height and weight, date of first OLT, serum alanine aminotransferase, asparagine aminotransferase, albumin, total bilirubin, cholinesterase activity, glomerular filtration rate, and prothrombin time. Significant independent predictors of survival after OLT were bilirubin (P=0.0024), SDS for weight (P=0.034), and albumin (P=0.039). In a subsequent discriminant analysis cut off points for these variables could be identified--i.e., bilirubin >340 micromol/L, SDS for weight <-2.2 and albumin < 33 g/L. Patients with one or more of these risk factors were grouped as urgent indication group (n=76) and those with no risk factor as elective indication group (n=42). Comparing the posttransplantation survival in these groups there is a statistically significant difference at 1 year (57% vs. 90.5%) and 4 years (49% vs. 90.5%) after OLT (P=0.0001, log rank test). It is concluded that the risk of OLT is much higher if liver function is very poor. Optimal nutritional support prior to transplantation is mandatory to optimise the clinical status of the children and to improve the results of OLT.

Oxalate elimination via hemodialysis or peritoneal dialysis in children with chronic renal failure.

Oxalate elimination and oxalate dialysance via hemodialysis (HD) or peritoneal dialysis (CAPD) has not been studied in detail in pediatric patients. We studied plasma oxalate, oxalate elimination, and oxalate dialysance in 15 infants and children undergoing CAPD (9 female, 6 male, aged 9 months to 18 years) and in 10 children on HD (4 female, 6 male, aged 7-18 years). Two children in each group had primary hyperoxaluria (PH). The mean duration of dialysis prior to examination was 12 +/- 11 months in CAPD and 31 +/- 23 months in HD patients. Bicarbonate HD was performed 5 h three times a week, CAPD consisted of five daily exchanges in 5 patients and four changes in the remaining 10 children (dwell volume 40 ml/kg body weight, 2.3 g/l glucose). Although oxalate dialysance was significantly higher in HD (mean 115.6 ml/ min per 1.73 m2 in HD versus 7.14 ml/min in CAPD), mean oxalate elimination per week was not different between both renal replacement therapies (3,478 mumol/1.73 m2 surface area/week in CAPD versus 3,915 mumol/1.73 m2 per week in HD). Oxalate elimination in patients with PH was between 6,650 and 9,900 mumol/week. Plasma oxalate remained elevated in both procedures [28-84 mumol/l in CAPD (92/148 in PH) and 33-101 mumol/l in HD (70/93 in PH)]. Oxalate elimination can be increased by a more frequent hemodialysis regimen.

[Long-term ursodeoxycholic acid treatment of cholestatic liver diseases in childhood--clinical and biochemical effects]. / Langfristige Ursodeoxycholsäurebehandlung cholestatischer Lebererkrankungen des Kindesalters--klinische und biochemische Effekte.

BACKGROUND: In adults with chronic cholestatic liver disorders, controlled studies have shown a reduction of clinical, biochemical and possibly histological parameters during long-term medication with ursodeoxycholic acid (UDCA). It is not yet clear, however, whether similar effects can be achieved in children. Therefore, we retrospectively evaluated the use of UDCA in typical liver diseases of childhood. METHOD: 20 children were treated for at least 6 months (age at start of therapy 5-87, median 24 months; diagnosis: biliary atresia n = 10, Alagille's syndrome n = 4, intrahepatic biliary hypoplasia n = 3, Byler disease n = 3). Pruritus, liver cell injury, cholestasis, synthetic liver function and weight and height for age before medication with UDCA (7-26, mean 13 mg/kg BW/d) was compared to values after 3, 6, 12, 18 and 24 months of therapy, with special attention towards possible adverse effects. RESULTS: No adverse effects of UDCA necessitating modification of therapy were encountered. During the first year of medication, weight for age improved in 15 patients, but pruritus in only four. During UDCA treatment, GIDH and gamma GT decreased significantly. GOT and GPT declined in the majority of patients. No significant changes of bilirubin and parameters of liver synthesis were seen. CONCLUSION: Long-term medication with UDCA appears to be safe in children. Thus, controlled studies of UDCA medication in children are justified, and are urgently needed to further investigate the prognostic significance of the positive effects of UDCA identified in this retrospective analysis.