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Central venous catheter (CVC) are being increasingly used as hemodialysis vascular access. In order to evaluate the indications, practice and uses in the pediatric population, we conducted a study in children with renal failure (RF). A questionnaire was sent to the 21 french paediatric hemodialysis centers to inquire population deserved, number, type, site and indications of CVC, procedure of management and attitude towards infection and thrombosis. A prospective survey was added to compile information about CVC during the period 7/2000-31/12/2000. Results (exhaustivity response 80%) showed 1. large diversity in choice of material with predominance of pediatric permcath QUINTON; 2. exclusive surgical insertion for 8 out of 19 centers; 3. rare use of femoral route (never and exceptionally reported, respectively by 4 and 6 centers and predominantly in acute RF; 4. heterogene attitude towards fixing, dressing, heparine locking and procedure of urokinase administration in case of thrombosis, whilst procedure towards infection was homogeneous; 5. indications of insertion of the 31 prospective study CVC were distributed in 4 subgroups a) breakdown of vascular permanent access (6 cases) or of peritoneal dialysis (2 cases), b) unexpected terminal renal failure (6 cases), c) deliberate choice to wait transplantation (4 cases) or to face breakdown of transplantation (4 cases), d) dysfunction of a previous CVC (7 cases); 6. a rate of 20% of dysfunction (flow problem); 7. a rate of replacement of 11%. AVC are effective forms of vascular access. However CVC indications should be carefully analysed and balanced if possible with alternative route such as anticipated creation of arterioveinous fistula, peritoneal dialysis and preemptive transplantation.

1. 1 alpha (OH) vitamin D3 derivatives have an inconstant long term inhibitory effect on PTH secretion. As a matter of fact they act by three mechanisms, one of these being antagonistic: 1) a direct inhibitory action on the prepro-PTH gene; 2) an indirect inhibitory action by increasing plasma calcium; 3) an indirect stimulatory action by increasing plasma phosphate. These two latter phenomena are due to the stimulation of the intestinal absorption of these ions as well as to an intrinsic osteolytic action which may override the inhibition of the bone release of these ions in relation with the decrease of the PTH plasma levels. 2. The use of 1 alpha (OH)D3 derivatives in patients on chronic dialysis is justified in about 30% of the patients on dialysis when in spite of native vitamin D repletion and adequate predialysis control of plasma calcium (2.5 +/- 2 mmol/l) and of plasma phosphate (1.4 - 1.7 mmol/l), the PTH plasma levels are 3 or 5 fold the upper limit of normal whether the patient is on hemodialysis or on CAPD. When hyperphosphatemia is > 1.7 mmol/l it is first necessary to correct it by the use of higher doses of alkaline calcium salts given with the meals as phosphate binder together with a negative perdialytic calcium balance induced by a lower dialysate calcium in order to avoid hypercalcemia. Control of hyperphosphatemia is indeed a necessary prerequisite for the long term PTH suppressive efficacy of 1 alpha OH vitamin D derivatives. 3. The use of 1 alpha(OH)D3 derivatives in the treatment of the predialysis uremic patients is even more limited because there is no additional mean to decrease the risk of hypercalcemia when oral calcium is used as phosphate binder because of the danger of aluminum and magnesium phosphate binders. Fortunately in the adult, oral calcium used as phosphate binder in association with phosphate restriction and correction of possible vitamin D depletion and acidosis is usually efficace to control hyperparathyroïdism without 1 alpha OH vitamin D3. This is not the case in the child to whom protein and phosphate restriction should not be prescribed because of its incompatibility with the Recommended Diet Allowance. Fortunately the high remodeling rate of his growing bones, decreases the risk of hypercalcemia due to the combination of CaCO3 and 1 alpha OH vitamin D3.

Unlabelled: To assess the prevalence of histologic bone disease in our center where Al(OH)3 intake is restricted, we reviewed 42 bone biopsies performed between 1975 and 1985 in patients dialyzed more than 29 months. Bone biopsies were performed systematically (2/3 of the cases) or because of a mild hypercalcemia (1/3 of the cases). Seventeen of these patients had been dialyzed before 1978 with softened water moderately contaminated by aluminum. Fifteen had always been dialyzed with reverse osmosis treated water and 10 had been exclusively treated by hemofiltration. The prevalence of osteitis fibrosa was 76%, that of osteomalacia null and that of adynamic bone disease 24% (but only 9.5% with positive Aluminon staining). When the 17 patients dialyzed with aluminum contaminated water before 1978 were excluded, only one patient among 25 had an aluminum adynamic bone disease (4%). This low prevalence can probably be explained by the restricted intake of Al(OH)3 thanks to the systematic administration of Ca CO3 and in a few cases of Mg (OH). The adynamic bone disease group has lower serum concentration of PTH and shorter duration on dialysis whereas the serum levels of calcium, phosphorus, magnesium and aluminum and daily dose of Ca CO3, Mg (OH)2 and Al(OH)3 do not differ. The frequency of the positivity of aluminum staining is not statistically different in the 2 groups. In 4 cases, adynamic bone disease without aluminum or iron intoxications is found, associated with a relative hypoparathyroidism. It is not explained by previous parathyroidectomy, diabetes or steroid therapy., Conclusions: 1) Restriction of aluminum intake and dialysis with reverse osmosis treated water lead to a low prevalence of aluminum bone disease. 2) A new bone disease in uremia is described: the idiopathic adynamic bone disease associated with a relative hypoparathyroidism.

After a protein load, the glomerular filtration increases to a maximum called maximal filtration capacity (MFC). The difference of this value with that observed in the fasting state defines the functional renal reserve (FRR). Fifty oral protein loads have been performed in 16 controls (13 adults and 3 children) and 31 patients with kidney disease or hypertension (22 adults, 9 children, 3 tests being performed twice). The load consisted in the adults of 80 g of various proteins. In the children the load consisted in the 100% of the protein intake recommended of the whole day. The urinary samples were made hourly during the 5 hours following the beginning of the meal. The MFC was not always observed during the 2 hours following the end of the meal. However the mean of the clearances measured during these 2 hours allowed an acceptable evaluation of the FRR in 42 out of 50 cases and had the advantage to reduce the errors linked to incomplete bladder voiding. In the adult controls the mean of hourly determined MFC is 156 +/- 27 ml/min, the mean of the clearances measured on the 2 hours following the meal is 136 +/- 21 ml/min and the fasting clearance 96 +/- 22 ml/min. The FRR is null in all patients with a nephropathy with a fasting clearance below 40 ml/min. It is modest or null in patients with acquired or congenital solitary kidney. Three out of five patients with proteinuria have MFC and FRR higher than the mean of the patients with comparable fasting clearances but without proteinuria suggesting that proteinuria is associated with a hyperfiltration state.

Unlabelled: The decrease of blood pressure and the increase of plasma renin activity (PRA) after oral administration of captopril was evaluated in 104 consecutive hypertensive out-patients in whom the morphology of the renal arteries and parenchyma was assessed thanks to an intravenous digitalized angiography. Twenty five of these patients were excluded because of a natriuresis less than 50 mmol/24 h or non discontinuation of their treatment; 50 of these patients were classified as essential hypertension, 12 had renovascular disease (10 unilateral stenosis 2 of which significant; 2 bilateral significant stenosis); 9 had unilateral small kidneys (4 significant). The significance was ascertained on the PRA in the renal veins and/or the decrease of hypertension after surgery. The decrease of blood pressure after captopril was not different between the various groups. The increase after captopril of PRA was higher in unilateral significant lesions. However the highest post captopril PRA value was found in the essential hypertension group so that renovascular diseases could not be screened by higher post captopril PRA values. However taking into account that these latter were decreasing with age, a better discrimination of significant unilateral disease was possible in the hypertensive patients above 40 years of age. Furthermore once the diagnosis of unilateral kidney disease is established by radiological investigation, the captopril test allows to predict unilateral hypersecretion of renin with a sensitivity of 100% and a specificity of 78%., In Conclusion: the captopril test does not allow to screen the non selected hypertensive patients for an efficient radiological investigation by intravenous digitalized angiography but may help to select the patients with unilateral renal disease for the renal venous PRA evaluation.