Cinacalcet HCl (Sensipar/ Mimpara) is an effective chronic therapy for hemodialysis patients with secondary hyperparathyroidism

AIMS

This 1-year double-blind, placebo-controlled, multicenter study evaluated the long-term safety and efficacy of cinacalcet for the treatment of secondary hyperparathyroidism in patients receiving hemodialysis.

METHOD

Patients were randomly assigned in a 1:1 ratio to cinacalcet or control treatment groups. The initial dose of cinacalcet (or matching placebo) was 30 mg. Doses were titrated every 3 or 4 weeks based on the intact parathyroid hormone (iPTH) response and safety profile. Sequential doses included 30, 60, 90, 120 and 180 mg/d. Phosphate binders and vitamin D sterols were adjusted per protocol as needed to control levels of calcium and phosphorus. Efficacy and safety were compared between treatment groups among patients who completed the study (52 total weeks of treatment). Reasons for withdrawal are presented for patients who did not complete the study.

RESULTS

A total of 210 patients completed 52 weeks of double-blinded treatment with cinacalcet (n = 99) or placebo (n = 111). Over the last 6 months of the study, a greater proportion of patients in the cinacalcet group than the control group achieved an iPTH level < or = 250 pg/ml (61.6 vs. 9.9%, p < 0.001) or a > or = 30% decrease in iPTH from baseline (81.8 vs. 21.6%, p < 0.001). Mean iPTH levels decreased by -47.8% in the cinacalcet group and increased by +12.9% in the control group. Mean percentage changes in other laboratory values in the cinacalcet and control groups included the following: serum calcium -6.5 vs. +0.9% (p < 0.001), serum phosphorus -3.6 vs. -1.1% (p = 0.465), and Ca x P -9.9 vs. -0.3% (p = 0.006). The most commonly reported adverse events related to study drug by the investigators included nausea (13% cinacalcet, 5% control), investigator-reported hypocalcemia (11% cinacalcet, 1% control), vomiting (9% cinacalcet, 2% control), dyspepsia (5% cinacalcet, 4% control), and diarrhea (5% cinacalcet, 2% control).

CONCLUSIONS

Treatment with cinacalcet is a safe and effective therapy for long-term control of secondary hyperparathyroidism. 1-year therapy with cinacalcet was associated with sustained, clinically significant reductions in calcium, Ca x P and iPTH which allowed a greater percentage of patients to achieve NKF-KDOQI target goals for PTH and Ca x P.

Angiotensin-converting enzyme gene polymorphism determines the antiproteinuric and systemic hemodynamic effect of enalapril in patients with proteinuric renal disease. Austrian Study Group of the Effects of Enalapril Treatment in Proteinuric Renal Disease

Angiotensin-converting enzyme (ACE) inhibitors are known to reduce blood pressure and proteinuria in a variety of different glomerular diseases. Nonetheless, a marked interindividual difference in the efficacy of these agents exists. The activity of the ACE and therefore of the renin-angiotensin-aldosterone system (RAAS) has been shown to be under genetic influence. Patients with a deletion genotype at the intron 16 of the ACE gene have been shown to exhibit higher activity of plasmatic ACE when compared to patients with the insertion genotype. We therefore studied prospectively the hemodynamic and antiproteinuric effect of a 6-month therapy with enalapril in patients with biopsy-proven proteinuric glomerular diseases and the DD (n = 10) and ID/II (n = 26) genotype. Although patients with the DD genotype received a slightly higher dose of enalapril, blood pressure and proteinuria did not change significantly. However, both were significantly reduced in the II/ID group after 10 weeks and 6 months of therapy. Creatinine clearance decreased steadily in DD patients. In II/ID patients, creatinine clearance was reduced significantly after 10 weeks of therapy but increased again thereafter and the value at 6 months was again comparable to the one obtained in the DD patients. We conclude from our study that the ACE genotype influences the blood pressure-lowering and antiproteinuric effect of enalapril in patients with proteinuric glomerular disease.

Posttransplant hemolytic uremic syndrome in adult retransplanted kidney graft recipients: advantage of FK506 therapy?

BACKGROUND

Posttransplant hemolytic uremic syndrome (pHUS) is a rare but severe disorder that confers a poor prognosis on an allograft due to thrombotic microangiopathy. Immunosuppression with cyclosporine (CsA) is implicated as a significant risk factor for the development of pHUS. In early reports, it was hypothesized that immunosuppression with FK506 (tacrolimus) would avoid the development of pHUS. However, this initially supposed beneficial effect remains controversial, because pHUS associated with tacrolimus therapy has been published in some later case reports. This article aims to further evaluate FK506 with respect to the development and resolution of pHUS.

METHODS

We describe the course of seven adult kidney graft recipients with pHUS, treated with FK506 either as initial immunosuppression for retransplantation or after discontinuation of CsA for resolution of pHUS. Work-up for pHUS was initiated when certain clinical features, such as hemolytic anemia, thrombocytopenia, and deterioration of graft function, were found. The diagnosis was confirmed by histologic examination of a renal allograft biopsy specimen (thrombotic microangiopathy). With the onset of pHUS, additional plasma exchange was performed in all patients.

RESULTS

Two patients suffered from end-stage renal disease due to primary HUS and had a history of recurrent pHUS in previous renal transplants. In both patients, the attempt to regraft was only made because of the early optimistic reports using FK506. Despite initial FK506 therapy, both recipients developed pHUS again, leading to loss of graft function. Two additional kidney graft recipients with primary renal failure other than HUS also received FK506 as initial immunosuppression. One of them (loss of the first kidney graft due to CsA-induced pHUS) was successfully treated with FK506 for his second renal transplant. The other recipient, a patient in whom de novo pHUS had occurred in the first graft despite initial therapy with FK506, was treated with CsA for his second graft and again developed pHUS. The latter process, however, could be reversed by a switch to steroids and azathioprine. In all three patients regrafted for reasons other than pHUS, development of de novo pHUS was treated by CsA withdrawal and a switch to FK506; this approach was effective in two patients.

CONCLUSION

Our results demonstrate that three of seven renal allograft recipients benefited from FK506 therapy for prevention or resolution of pHUS. Treatment or prophylaxis with FK506 can be considered advantageous in some patients with de novo pHUS, but FK506 fails to prevent recurrent pHUS in patients with primary HUS.

Monocyte activation and humoral immune response to endotoxins in patients receiving on-line hemodiafiltration therapy

With the on-line preparation of substitution fluid, an easy-to-operate and cost-effective alternative to conventional hemodiafiltration (HDF) has been realized. The continuous filtration of dialysis fluid, furthermore, allows high volumes of exchange. Microbial contamination and subsequently endotoxins, however, may be present in dialysis fluid, and thus the microbiological safety has become a pivotal issue. In this clinical study we evaluated the safety of the Fresenius Medical Care on-line HDF system which is based on a two-stage filtration of dialysis fluid with upstream DIASAFE and downstream on-line HDF filter. During the three-month study period we failed to detect germs or endotoxins in the substitution fluid. Augmented plasma interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNFalpha) concentrations were found neither during the intradialytic period nor when pre-session values at study begin and study end were compared. In addition, changes in the anti-endotoxin core antibody levels and soluble CD14 (sCD14) concentration, or pyrogenic episodes were not observed. On-line HDF with DIASAFE and on-line HDF filter thus represents a safe treatment modality by effectively depleting dialysis fluid of cytokine-inducing substances.

[Aerobic and anaerobic capacity of chronic hemodialysis patients under continuous therapy with recombinant human erythropoietin]

In earlier studies we have shown that partial correction of anemia by recombinant human erythropoietin (r-HuEPO) already after 12 weeks results in a significant increase of exercise capacity in patients on chronic hemodialysis. As causative effect increased oxygen availability with improved oxygen delivery to the tissues was assumed. To elucidate the long-term effects of a partial correction of anemia with r-HuEPO on exercise capacity, oxygen uptake at maximum exercise and at the anaerobic threshold was measured by repetitive spiroergometry. Measurements were done before, 3 months and 6 months after initiation of r-HuEPO therapy. The results are summarized below: (table; see text) Our results show that a long-term improvement of peripheral oxygen availability leads to a further increase of anaerobic threshold in patients on chronic hemodialysis even without a further increase of hemoglobin levels and without exercise training. It appears that elimination of the chronic hypoxic condition results in a restoration of previously diminished mitochondrial enzymes in muscle, particularly for aerobic glycolysis. Besides acute improvement of aerobic and anaerobic exercise capacity, the long-term administration of r-HuEPO with its increased anaerobic threshold enhances the patients' everyday life working capacity.

Working capacity is increased following recombinant human erythropoietin treatment

To investigate the effect of partial correction of anemia in patients maintained by chronic intermittent hemodialysis on aerobic and anaerobic working capacity, eight patients underwent a bicycle spiro-ergometry before and after treatment with recombinant human erythropoietin (r-HuEPO). the initial mean (+/- SD) hemoglobin value was 5.9 mg/dl +/- 0.61 and increased during treatment to 10.9 +/- 0.59 mg/dl, P less than 0.0001). This partial correction of anemia resulted in a significant increase of both oxygen uptake at the anaerobic threshold and peak peripheral oxygen uptake at subjective exhaustion (P less than 0.01 and P less than 0.0002, respectively). The increase in oxygen uptake corresponded to significant increases in Watts, both at the anaerobic threshold and at maximum workload (P less than 0.02 and P less than 0.0004). These data show that partial correction of renal anemia results in a significant increase of both exercise capacity and maximum work.

[Ethylene oxide-induced antibodies and hypersensitivity reactions in hemodialysis]

The presence of antibodies against ethylene oxide, which is used for sterilization of dialyzers, was evaluated in 52 hemodialysis patients (30 male, 22 female). The aim of the prospective study was to evaluate a possible correlation of these antibodies with hypersensitivity reactions during hemodialysis. By means of a radio-allergo-sorbent-test (RAST) only 3.9% (2 patients) were detected to have ethylene oxide antibodies. There was no significant correlation between antibodies on the one hand, and symptoms, eosinophilia and IgE-elevation on the other hand. We could not find ETO-induced hypersensitivity reactions in our study population. Thorough rinsing and sufficient storage time of the dialyzers might be the reasons for these findings.

Acute oliguria associated with chlorprothixene overdosage

The occurrence of acute reversible oliguria is described in a 23-year-old male after ingestion of 1,500 mg of chlorprothixene in a suicidal attempt. In contrast to earlier reports hypothesizing that the pathophysiology of the renal insufficiency associated with chlorprothixene intoxication may be attributed to direct nephrotoxic effects of the compound or to ischaemia owing to transitory unrecognized shock, a careful diagnostic work-up including renal biopsy, disclosed the presence of acute interstitial nephritis.

[Effectiveness of recombinant human erythropoietin in the treatment of transfusion-dependent anemia in patients on chronic dialysis]

Recombinant human erythropoietin (r-HuEPO) has recently become available for clinical trial and has been used for the first time in Austria for the treatment of transfusion dependent patients on chronic haemodialysis. Inclusion criteria into the study were baseline haemoglobin levels of less than or equal to 6 g/dl and transfusion requirements of greater than or equal to 1 unit of blood per month. r-HuEPO (CILAG/AMGEN/ORTHO) was administered intravenously 3 times weekly at the end of dialysis. The initial dose was 100 U/kg body weight at each administration and was increased by 25 U/kg if Hb levels failed to increase by greater than 5% of baseline at intervals of 3 weeks. All 9 patients studied showed an increase in Hb values to the desired value at least greater than or equal to 10 g/dl within 6 to 16 weeks and none of the patients required further blood transfusions. All patients reported subjective improvement of life quality and markedly increased working ability. Apart from minor episodes of bone pain and subfebrile temperatures after r-HuEPO administration no major side effects were noted. These preliminary results show that r-HuEPO (CILAG/AMGEN/ORTHO) is a safe and effective form of therapy for renal anaemia and one which opens new horizons in the management of patients on chronic haemodialysis.

Blood-membrane interaction in hemodialysis leads to increased cytokine production

Recently much interest has been focused on the role of immunoregulatory cytokines such as interleukin 1 (IL 1) and interleukin 2 (IL 2) during the pathogenesis of immunological as well as inflammatory diseases. Therefore peripheral blood mononuclear cells (PBMC) of eight patients undergoing hemodialysis (HD) were tested for IL 1 and IL 2 production. Before starting HD, cytokine production by PBMC in culture was not altered in comparison to normal healthy controls, however, a significant increase of IL 1 and IL 2 production was observed within the first HD hour which lasted throughout the end of HD. Moreover direct effects of cellulose membranes on PBMC cytokine production as well as serum IL 1 levels have been investigated. Serum IL 1 levels were already elevated before onset of HD and increased further during HD. The discrepancy between PBMC IL 1 production and serum IL 1 levels may be due to the diminished excretion in patients with end-stage renal disease. Since addition of dialysis membrane particles enhanced monocytes to produce more IL 1 as well as lymphocytes to release more IL 2, a direct stimulatory membrane effect is postulated. The increased release of immunoregulatory cytokines may account for some of the pathologic findings observed during hemodialysis.

Abnormalities in the hypothalamic-pituitary-adrenocortical axis in patients with chronic renal failure

The recently described human corticotropin-releasing factor was administered to eight patients with chronic renal failure in order to assess hypothalamic-pituitary-adrenocortical (HPA) function. Acute administration of corticotropin-releasing factor lead to a diminished increase of the basally elevated levels of ACTH and beta-endorphin immunoreactivity in patients on chronic hemodialysis. Basal plasma cortisol concentration was normal in end-stage renal disease; however, considering the corresponding elevated ACTH concentrations, cortisol levels were inadequately low. Thus, the hypothalamus as well as the adrenal gland seems to contribute to the alterations in HPA function observed in patients with chronic renal failure; involvement of the pituitary gland and effects of metabolic alterations cannot be ruled out.

Decreased serum interleukin 1 activity and monocyte interleukin 1 production in patients with fatal sepsis

The role of interleukin 1 (IL 1) in 16 patients with sepsis and 16 normal controls was investigated. Thymocyte costimulation was used to assay in vitro IL 1 levels produced by adherent cells in the peripheral blood, and in vivo IL 1 levels in the serum. Adherent cells (i.e., monocytes) from nonsurviving septic patients produced significantly less IL 1 activity than cells from healthy controls or surviving patients, either spontaneously or by silica stimulation. In contrast, in vitro IL 2 production by T lymphocytes was not altered in septic patients. Serum IL 1 activity was determined using serum fractions from high-pressure liquid chromatographic gel filtration. Suppressor factors in healthy subjects as well as septic patients usually eluted at molecular weights above 50 kilodaltons, while IL 1-like activity was normally present between 35 and 1 kilodaltons. Sera of nonsurviving septic patients contained significantly less IL 1 compared to that of controls or surviving patients. Thus, decreased serum IL 1 levels and diminished monocyte production of IL 1 appear to be negative prognostic indicators, possibly reflecting a breakdown of mononuclear phagocytes.

Radioimmunoassay of atrial natriuretic peptides in human plasma

The concentration of atrial natriuretic peptide (hANP) in plasma from venous blood of healthy subjects was measured by radioimmunoassay. hANP from 5 mL of EDTA-treated plasma was adsorbed onto Sep-Pak C18 cartridges, which were eluted with methanol/trifluoroacetic acid (5 mL/L), 90/10 by volume. The eluates were concentrated by evaporation under nitrogen and lyophilized. After redissolving the samples in 0.5 mL of sodium phosphate buffer, we incubated 100-microL aliquots with anti-alpha-hANP for 24 h, then added 125I-labeled alpha-hANP tracer; 24 h later, we separated the bound and free fraction by adding an antibody/polyethylene glycol complex as the second antibody. The sensitivity of the assay was 2 pg per tube (B0-3 SEM). In the useful range of B = 15 to 85% of B0, CVs for within-run and between-run precision did not exceed 8 and 12%, respectively. The 50% intercept of the standard curve was at 12 pg per tube. hANP concentrations for 36 healthy adults ranged from 8 to 68 ng/L.

Center-specific variations of thyroid hormone serum levels in hemodialysis patients

Thyroid hormone (free and total thyroxine, total 3,5,3'- and 3,3'5'-triiodothyronine, thyroxine-binding globulin, thyrotropin) serum concentrations were measured in 107 uremic patients of 4 hemodialysis centers, in order to study the prevalence of hypothyroidism in hemodialysis patients. In accordance with the clinical impression there was no laboratory evidence of thyroid dysfunction. In spite of the fact that all patients had the expected low-T3 syndrome, there were highly significant differences between the mean thyroid hormone concentrations of the 4 different centers. The center with the highest thyroid hormone levels (all normal except for borderline low 3,5,3'-triiodothyronine) also had the lowest urea levels, indicating the relatively best metabolic control. One center had significantly lower hormone levels than the other 3 centers (all hormones except free thyroxine were below normal) with urea levels that did not differ significantly from one of these centers. A retrospective analysis of patients and of the techniques of dialysis of 3 centers excluded factors like heparin or the length of time on dialysis to be the reason for the low values of this center. Finally, only the significantly higher proportion of unsuccessfully transplanted patients and some technical differences (lack of water treatment, regenerated cellulose as dialyser membrane, and low magnesium content in the dialysate) unique for this center remained as possible factors that may speculatively explain the observed low thyroid hormone values.(ABSTRACT TRUNCATED AT 250 WORDS)

[Individual dialysis using computer-controlled prescription]

The use of urea kinetics as basis for optimization and individualization of renal replacement therapy has become quite popular over the last decade. The rationale underlying the use of blood urea nitrogen for monitoring or targeting dialysis therapy is based on the report of an American multicentre cooperative dialysis study showing that blood urea nitrogen concentrations are closely correlated to the occurrence of morbidity and complications in dialysis patients. In order to further optimize the accuracy of dialysis prescription we have developed a new algorithm for estimation of the dialysis time needed to reach a certain blood urea nitrogen concentration, which--in contrast to all methods employed so far--enables accurate calculation of ultrafiltration during haemodialysis and of weight changes in the interdialytic period.

[Intrapulmonary percussion. A new method of respiratory therapy]

Intrapulmonary percussion with a high-frequency jet system is a new method in the treatment of respiratory impairment. It imitates the conventional percussion massage of the thorax by introducing high-frequency gas oscillations (300 impulses per minute) into the tracheobronchial system. In 14 patients with abnormal alveolo-arterial oxygen differences due to bronchial mucostasis ventilation was satisfactorily improved by its application.

[Continuous arteriovenous hemofiltration in the therapy of acute renal insufficiency]

30 patients with acute renal failure were treated in an intensive care unit by continuous arterio-venous haemofiltration (CAVH). This procedure has less side effects as compared with intermittent haemodialysis, peritoneal dialysis and haemofiltration (hypotension, bio-incompatibility and lack of biochemical steady state) and CAVH is clearly superior with regard to fluid removal. In removing the uraemic toxins CAVH is more effective than peritoneal dialysis and, in most instances, satisfactory as sole renal replacement therapy in acute renal failure.

Chronic hemodialysis: high risk patients for arrhythmias?

Patients with end-stage kidney disease undergoing chronic maintenance dialysis (HD) are a high risk group for sudden death due to cardiovascular complications. It was the aim of the study to investigate the quantity and quality of arrhythmias during HD and between two consecutive HD (interval, I) with regard to the reproducibility of the expected results. 15 patients (8 males, 7 females) underwent continuous Holter monitoring (LT-ECG) under ambulatory conditions over 96 h including two HD ( HD1 + HD2 ) and two intervals (I1 + I2). The LT-ECG recordings were analysed with the computer assisted ' Multipass -Scanning' system with regard to heart rate (HR), supraventricular premature beats (SPB), ventricular ectopics (PVC) and malignant ventricular arrhythmias.

RESULTS

The HR demonstrated a typical, well-known circadian pattern with remarkable increase of the HR during each HD. Except for rare, single SPB and/or PVC, no supraventricular or ventricular arrhythmias could be detected reproducibly. Single PVC occurred in patients with a lower potassium value. No malignant ventricular arrhythmias were found. In comparison to previously published studies, which demonstrated a high incidence of malignant ventricular arrhythmias, these conflicting results were due to differences in patients' recruitment (underlying disease, age, etc.), the performance of HD (duration, ion concentration of the dialysate etc.), serum potassium levels and drug medication (digitalis, quinidine). In summary, chronic HD per se did not enhance the risk of malignant arrhythmias in patients with end-stage kidney disease.

Spontaneous arteriovenous plasma separation

Plasmapheresis (PP) therapy was carried out by spontaneous arteriovenous membrane plasma separation. By cannulating the femoral artery and vein by Seldinger technique, this method could be performed by natural arteriovenous pressure gradient without blood pumps or special monitoring. Eight patients experienced 44 PP therapies without complication in the ICU. Spontaneous arteriovenous membrane plasma separation can suitably be combined with continuous arteriovenous hemofiltration.

[Disorders of hormone metabolism in chronic uremia]

Uremia is accompanied by a variety of "true" and "laboratory" endocrine disorders, due in part to impaired degradation of hormones because of failing kidney function and in part to the interference of the uremic environment with extrarenal degradation or synthesis and secretion of certain hormones. "True" endocrine disorders, like hyperparathyroidism or hypogonadism, that are associated with renal insufficiency are in contrast with "laboratory" endocrine disorders in uremia, where pathological serum hormone levels lack clearcut clinical evidence for dysfunction of the respective endocrine organ (e.g. thyroid gland). This lack of a direct cause and effect relationship in uremia may be due to the fact that immunoassayable hormone levels may include cross reacting components without biological activity in uremia and to the fact that the uremic environment may alter hormonal effects on target organs. This review tries to give a survey of the big amount of available clinical and laboratory data for uremia induced changes in the following hormones: growth hormone and somatomedins, prolactin, cortisol and adrenocorticotrope hormone, the gonadal and thyroid function as well as parathyroid hormone action. The knowledge of these uremia-induced changes should facilitate the clinician the diagnosis of an additional primary endocrine ailment in a uremic patient and should, on the other hand, spare these patients unnecessary treatment for a suspected endocrine disorder.

[High-density-lipoprotein and renal insufficiency (author's transl)]

Disturbances in lipid metabolism and accelerated atherosclerosis are well-known phenomena of chronic renal insufficiency. The disturbance in lipid metabolism has been repeatedly described as secondary type IV hyperlipoproteinemia according to the classification of Fredrickson. The classification of Fredrickson, however, does not take into account the role of the alpha-lipoproteins (the HDL lipoproteins and HDL cholesterol). Hence, HDL cholesterol was determined and correlated to other routine parameters of lipid metabolism in 66 patients with different degrees of renal insufficiency. Furthermore, an intravenous fat tolerance test was performed in 14 patients with terminal renal insufficiency. Beside the well-known hypertriglyceridemia with cholesterol values near the upper limits of normal, a significant reduction in HDL cholesterol was found, showing a significant inverse correlation to plasma creatinine values. Patients with advanced or terminal renal insufficiency additionally showed a significant inverse correlation between HDL cholesterol and plasma triglycerides. The disappearance rate of intravenously administered fat emulsion (which corresponds to the clearance rate of chylomicrons and VLDL) was diminished in azotaemic patients, showing a significant inverse correlation between HDL cholesterol and disappearance rate in the intravenous FTT. Beside hypertriglyceridemia, the diminished HDL cholesterol values represent an additional risk factor for the genesis of accelerated atherosclerosis. The diminished k value demonstrates a diminished activity of lipoprotein lipase as cause of hypertriglyceridemia, whereby the positive correlation between the k value and HDL cholesterol and the inverse correlation between HDL cholesterol and triglycerides suggest a causal relationship between the decreased activity of lipoprotein lipase and diminished HDL cholesterol levels.

[Hyperparathyroidism in chronic renal insufficiency new clinical and surgical aspects (author's transl)]

The therapy of secondary hyperparathyroidism in chronic renal disease has been improved by the availability of active 1-alpha-hydroxylated vitamin D derivatives. However, in cases with progressive secondary hyperparathyroidism which have not been brought under control conservatively, surgical intervention is still required. Total parathyroidectomy with autologous transplantation of parathyroid tissue in the forearm has recently been recommended as the optimum surgical approach to secondary hyperparathyroidism. Recent literature is reviewed and personal clinical experience is reported in this paper, followed by a presentation and discussion of the pathophysiology of hyperparathyroidism in chronic renal failure, various means of conservative treatment, indications for parathyroidectomy, surgical aspects and technique of cryopreservation, as well as a standardized therapeutic regimen for pre- and postoperative treatment with calcium and 1-alpha-hydroxylated vitamin D analogues.

Aluminum removal by hemodialysis

Aluminum kinetics were studied in 24 patients on chronic hemodialysis. All patients had elevated predialytic serum concentrations of aluminum (mean, 3.44 mumoles/liter), which correlated significantly with the ingestion of aluminum hydroxide (P less than 0.01). Simultaneous measurements of aluminum in plasma and ultrafiltrate revealed an ultrafiltrability of about 20% of total plasma aluminum, thus suggesting that 80% of aluminum is protein bound. When a dialysate with a very low aluminum content (varying from 0.1 to 0.3 mumoles/liter) was used, mean values across the dialyzer were 3.20 and 2.67 mumoles/liter, respectively, showing a significant decrease of plasma aluminum during dialyzer passage (P less than 0.0001). It could be shown that dialysance of aluminum depends on the concentration gradient between the free diffusible plasma aluminum and the dialysate aluminum concentration. After 6 hours of dialysis, plasma aluminum concentrations were significantly lower than were predialysis values (P less than 0.0001). We conclude that a negative aluminum balance during hemodialysis can be assumed as long as the aluminum concentration of free diffusible plasma aluminum lies above the aluminum concentration of the dialysate.

Renal phosphate wasting after successful kidney transplantation: 1-alpha vitamin D therapy in patients with normal parathyroid gland activity

1 alpha-hydroxycholecalciferol was tried as a therapy for renal phosphate wasting in kidney allograft recipients with normal parathyroid gland activity. During a 3-week period of treatment we observed a significant rise in renal phosphate threshold concentrations and plasma phosphate levels paralleled by a significant decrease in serum immunoreactive parathyroid hormone levels and a significant increase in intestinal calcium absorption. It is suggested that 1 alpha-hydroxycholecalciferol acts on renal phosphate handling in a dual fashion: one is by suppression of parathyroid hormone and the other by restoration of 1,25-dihydroxycholecalciferol levels to an appropriate level.

Enhanced 6-oxo-PGF1 alpha levels in plasma during hemodialysis

The activation of platelets due to foreign surface interaction is a well known fact. Earlier, we found an increase of circulating platelet microaggregates (method of Wu and Hoak) during hemodialysis. Since this phenomenon might cause a PGI2-release by lung and/or vascular tissue, we studied the plasma 6-oxo-PGF 1 alpha-levels in 6 patients during hemodialysis. We found an initial increase of plasma 6-oxo-PGF 1 alpha. Coincidently, hypoxemia, fall in platelet and lekocyte count and a decrease in platelet count ratio were observed. An effect of heparin was excluded in a control group. The findings support the hypothesis that PGI2 acts as a defense mechanism against platelet deposition on vascular wall by a temporary increased synthesis which could be monitored by a temporarily enhanced plasma 6-oxo-PGF 1 alpha-level during the initial phase of hemodialysis.

[Interaction between blood platelets and capillary kidney in haemodialysis (author's transl)]

In haemodialysis an interaction between platelets and the dialysator membrane occurs, which is not prevented by heparin. This can be demonstrated by parietal depositions of platelets in the capillaries of the artificial kidney by scanning electron microscopy, as well as in a marked increase of reversible platelet microaggregates during the first phase of dialysis. Some patients are prone to develop thrombosis of the capillary kidneys in spite of a high-dose heparinization. In these cases the use of diclofenac, a cyclooxygenase inhibitor, prevents these adverse platelet reactions.

[Haemodialysis in children (author's transl)]

Thirty four children, aged 2 to 15 years, were treated by haemodialysis between 1967 and 1978. Eleven children suffered from acute renal failure. Twenty three children with end-stage chronic renal disease were treated over periods ranging from 1 week to 19 months. All children were dialysed in a renal unit for adult patients awaiting renal transplantation. Our results refer especially to the technical equipment for paediatric dialysis and to the problems of blood access. The medical problems of chronic uraemia and chronic intermittent haemodialysis in children are discussed. From our experience we conclude that a sufficient degree of rehabilitation can be reached only in a paediatric dialysis unit.

Effect of 1 alpha hydroxylated vitamin D on steroid induced calcium malabsorption

As persistent bone loss is a major problem of chronic steroid therapy the effects of 3 weeks therapy with 1 alpha hydroxycholecalciferol were studied in 10 kidney transplant recipients on chronic steroid therapy. Treatment resulted in a significant increase in intestinal calcium absorption, paralleled by a significant decrease of serum iPTH, whereas neither plasma calcium nor urinary calcium excretion rose significantly, suggesting a positive calcium balance throughout the study. It is therefore suggested that administration of active vitamin D metabolites is an effective protection against one of the pathogenic mechanisms of steroid induced osteopenia.

Disappearance of uraemic pruritus after lowering dialysate magnesium concentration

Images

[Calcium and phosphorus metabolism in patients on chronic intermittent haemodialysis with different calcium concentrations in the dialysate (author's transl)]

A study was carried out in 25 patients on chronic intermittent haemodialysis on the effect of increasing the dialysate calcium concentration from 1.5 to 1.75 mMol/l on calcium and phosphorus metabolism. In 16 patients the increase in the dialysate calcium resulted in a sufficiently large increase in the plasma Ca level to suppress the parathyroid glands. The calcium influx during dialysis in these patients was sufficient to abolish the effects of diminished calcium absorption from the intestine due to loss of endocrine renal function. The remaining 9 patients showed no suppression of parathyroid gland activity and could be separated into two different groups, one requiring calcium supplementation and the other group manifesting signs of autonomic hyperparathyroidism. The five patients showing a higher calcium requirement were started on active vitamin D metabolites. In the remaining 4 patients parathyroidectomy will probably be inevitable if progression of the clinical manifestations of hyperparathyroidism occurs. Close control of plasma phosphorus levels is mandatory to avoid an increase in the calcium phosphate product or the danger of hypophosphataemic osteomalacia.

[Circulating platelet aggregates during haemodialysis]

In eight chronically haemodialysed patients a significant increase of circulating platelet aggregates (method of Wu and Hoak) was observed immediately after starting haemodialysis. The number of aggregates decreased at the end of haemodialysis reaching the starting values after 360 min. The platelet interaction with the dialysis membrane surface might cause this phenomenon. Anticoagulation with heparin alone was insufficient in preventing aggregate formation during haemodialysis.