Kinetics of aluminoxamine and feroxamine chelates in dialysis patients

To achieve a rational basis for the use of deferoxamine (DFO) in aluminum (AL) -and iron (Fe)-overloaded uremic patients, important insights may be provided by the recently available micromethods to determine DFO and its metallochelates aluminoxamine (AlA) and feroxamine (FeA). With this procedure, AlA and FeA plasma kinetics were evaluated in a pilot study in 10 uremic patients during a whole week after a single DFO infusion performed during the first hour of the first standard bicarbonate hemodialysis (HD) of the week. Patients were divided into normal (n = 6) and high (n = 4) ferritin groups (1 and 2 respectively). Baseline Al concentrations were greater than 2 less than 6 in group 1 and less than 1.5 mumol/l in group 2. DFO was given at doses of 40, 20 and 10 mg/kg. AlA and FeA showed substantially different kinetics. AlA kinetics were similar in group 1 and 2: they reached their peak at the beginning of the 2nd HD, decreased during the 2nd and 3rd HD, and with the highest DFO dose still increased between the 2nd and 3rd HD. At similar pre-DFO Al values (greater than 2 less than 3.3 mumol/l), increased DFO doses produced increased AlA concentrations ranging from 95 to 40% of total plasma Al for all the week. At higher pre-DFO Al values (greater than 3.5 less than 6 mumol/l), even a DFO dose as low as 10 mg/kg was sufficient to form consistent AlA amounts (from 80 to 15% of total Al).(ABSTRACT TRUNCATED AT 250 WORDS)

Recombinant human erythropoietin reduces free erythrocyte protoporphyrin levels in patients on chronic dialysis

We studied the significance of free erythrocyte protoporphyrin (FEP) in relation to iron status, aluminum levels and anemia in uremic patients on chronic dialysis. All but 1 patient showed high FEP values closely related to the degree of anemia. Increased FEP levels are due to a defective heme synthesis, not related to iron deficiency or aluminum overload. Treatment of anemia with recombinant human erythropoietin reduced FEP values. We therefore hypothesize that recombinant human erythropoietin ameliorates an enzymatic defect in heme synthesis.

Determination of aluminum in biological fluids by furnace atomic absorption spectrophotometry

Detailed procedures were developed for the furnace atomic absorption spectrophotometry (FAAS) determination of aluminum (Al) in serum, urine, cerebrospinal fluid (CSF), and proportionated dialysate. Of particular note were the use of Mg (NO3)2.6H2O as a matrix modifier and the employment of the standard additions routine in analysis. The accuracy of the method(s) used is supported by work with assayed controls and by recovery studies. The use of a "clean room" was shown to be unnecessary. Normal serum, urine, and CSF Al ranges observed were 4.8-8.9, 5.1-9.1, and 1.0-5.8 micrograms L-1 respectively.

Autonomous hyperparathyroidism not associated with increased aluminum absorption

A single 6-g dose of aluminum hydroxide was given to eight patients on regular hemodialysis before and 3 days after parathyroidectomy (PTX). Serum aluminum levels were measured before and after 5 h after ingestion of aluminum hydroxide to examine indirectly the effects on absorption of aluminum from the gastrointestinal tract of both high and low parathyroid hormone (PTH). Plasma PTH levels fell significantly from 2,724 +/- 1,830 ng/l (mean +/- 1 SD) before PTX to 352 +/- 63 ng/l after PTX. However, no significant change was detected in serum aluminum levels before or after PTX (1.45 +/- 0.96 to 1.92 +/- 0.88 mumol/l before PTX; 2.02 +/- 1.41 to 2.89 +/- 1.19 mol/l after). These findings indicate that in patients with chronic renal failure, high plasma levels of PTH are not associated with significant increases in serum aluminum concentrations after ingestion of a large quantity of aluminum hydroxide. Parathyroid hormone may not enhance intestinal absorption of aluminum in humans.

Effect of hypophosphatemia on muscle metabolism after exercise in pigs

Five Swedish Landrace pigs with a mean weight of 51 +/- 5 kg performed an exercise test on a treadmill at a speed of 1.8 m/s and a duration of 10 min. Hypophosphatemia was then induced in these pigs by addition of aluminium hydroxide (liquid antacid) to the normal feed. After 3 weeks, the exercise test was repeated when the mean weight of the pigs was 65 +/- 9 kg. Five other Swedish Landrace pigs with a mean weight of 72 +/- 4 kg performed a similar exercise test. Muscle biopsies from M. biceps and blood samples were taken from all pigs 3-5 days before and immediately after each exercise test. Hypophosphatemic pigs had significantly lower serum phosphate and higher aluminium levels than normophosphatemic pigs. In all pigs, glycogen content in muscle decreased significantly (-108 to -135 mmol/kg muscle) with exercise while no changes were seen in adenosine triphosphate, creatine phosphate or inorganic phosphate concentrations. In normophosphatemic pigs, glucose-6-phosphate and lactate concentrations increased significantly during exercise by 2-4 mmol/kg and 12.8-14.4 mmol/kg, respectively. However, in hypophosphatemic pigs, glucose-6-phosphate concentrations decreased significantly during exercise by 4.4 mmol/kg and lactate levels were unchanged. These results indicate that low serum inorganic phosphate levels influence muscle metabolism and glycolysis in connection with physical exercise.

Aluminium transport in blood serum. Binding of aluminium by human transferrin in the presence of human albumin and citrate

The binding of Al3+ by human serum transferrin has been investigated by u.v.-visible difference spectroscopy. In the presence of 25 mM-HCO3- at pH 7.4, the apparent association constants were found to be 1.69 x 10(12) M-1 and 5.36 x 10(11) M-1. These association constants are pH-dependent, reducing with both increasing and decreasing pH. The apparent pKa values were found to be 6.7 and 8.2. Competitive assays of binding of Al3+ to transferrin in the presence of citrate and human serum albumin at molar ratios corresponding to those found in normal plasma showed that a considerable amount of Al3+ was not bound to transferrin. Taking a concentration of 5 microM as a typical value observed for the plasma of patients on haemodialysis [Harris & Sheldon (1990) Inorg. Chem. 29, 119-124] the competitive binding assay indicate that approximately 60% of it is bound to transferrin, approximately 34% to albumin and the remainder to citrate. These results therefore suggest that, although transferrin at pH 7.4 is the major Al(3+)-binding component of plasma, an appreciable amount of Al3+ present in patients on haemodialysis may be bound to albumin.

Aluminum decreases the zinc concentration of soft tissues and bones of rats fed a low calcium-magnesium diet

The relationship between magnesium (Mg) and zinc (Zn) in soft tissues and bone of rats was studied after administration of unbalanced mineral diets. Minerals and metals in soft tissues and bone were determined using inductively coupled plasma emission spectrometry (ICP). There were significant positive correlations between serum Zn and Mg levels, between serum Zn and Zn content of soft tissues and bone, and between serum Mg levels and Zn content of bone and soft tissues in rats fed unbalanced mineral diets. A significant positive correlation was also found between Zn and Mg content in the lumbar spine and femoral bone of rats. It appears that altered bone mineralization induced by unbalanced mineral diets leads to mobilization of Mg and Zn from rat bones in similar ways.

The hypocholesterolemic effect of an antacid containing aluminum hydroxide

STUDY OBJECTIVE

To evaluate the efficacy, safety, and hypocholesterolemic effect of an aluminum hydroxide-containing antacid in hypercholesterolemic individuals.

DESIGN

A prospective, randomized, double-masked, placebo-controlled phase of 2 months' duration, followed by an open-design treatment phase of 2 months' duration and a washout phase of 2 months' duration.

SETTING

Family practice clinics of two rural communities (kibbutzim) in Israel.

PATIENTS

Fifty-six men and women with hypercholesterolemia (type IIa or IIb). Fifty individuals completed the study.

INTERVENTION

After 2 months of dietary modification (low-fat, low-cholesterol diet), the participants were randomized into two matched groups. Group 1 (28 participants) was treated for 2 months with a chewable antacid tablet containing simethicone, magnesium hydroxide, and 113 mg of aluminum hydroxide per tablet, at a dose of two tablets four times daily. Group 2 (22 participants) was given a similar number of placebo tablets for 2 months. During the following 2 months, both groups received the antacid at the above dose.

MEASUREMENTS AND MAIN RESULTS

Lipoprotein levels were evaluated at baseline and every 2 months thereafter for 6 months. Compared with pretreatment levels, Group 1 experienced a decrease in low-density lipoprotein cholesterol (LDL-C) of 9.8% after 2 months (p less than 0.001) and 18.5% after 4 months (p less than 0.001). Compared with Group 2, the decrease in LDL-C in Group 1 was 6.2% at the end of the 2-month double-masked, placebo phase. Although the high-density lipoprotein cholesterol (HDL-C) was also reduced in Group 1 at the end of 4 months of therapy (10.2%), the HDL-C/LDL-C ratio increased by 13% during the same interval (p less than 0.05). The treatment was well tolerated, with minimal side effects.

CONCLUSIONS

An aluminum hydroxide-containing antacid reduces LDL-C in hypercholesterolemic individuals. Although HDL-C was also reduced to a lesser extent, the overall atherogenic index was improved. Further studies should be conducted to evaluate the long-term safety and efficacy of antacids containing aluminum hydroxide in hypercholesterolemic patients.

Evidence of aluminium accumulation in aluminium welders

Using atomic absorption spectrometry the aluminium concentrations in blood and urine and in two iliac bone biopsies obtained from welders with long term exposure to fumes containing aluminium were measured. The urinary excretion of two workers who had welded for 20 and 21 years varied between 107 and 351 micrograms Al/l, more than 10 times the concentration found in persons without occupational exposure. Urinary aluminium excretion remained high many years after stopping exposure. Blood and bone aluminium concentrations (4-53 micrograms Al/l and 18-29 micrograms Al/g respectively) were also raised but not to the same extent as urine excretion. It is concluded that long term exposure to aluminium by inhalation gives rise to accumulation of aluminium in the body and skeleton of health persons, and that the elimination of retained aluminium is very slow, in the order of several years.

[Research on the treatment of secondary hyperparathyroidism as a complication of chronic renal failure]

The effects of internal treatment were compared with those of surgical procedures on secondary hyperparathyroidism as a complication of chronic renal failure patients in order to study their applications and problems. Maintenance hemodialysis patients complicated with 2HPT were selected as test subjects. The following internal treatment was administered. 1) Elcitonine to 6 cases and 2) Ipriflavon to 5 cases respectively and applied 3) pulse therapy of 1.25(OH)2D3 to 12 cases. On the other hand, total parathyroidectomy and autotransplantation were carried out as surgical procedures. The results of the treatment were evaluated by comparing serological data including tartrate resistant acid phosphatase (TAP) measured with the passage of time, bone scintigram findings, and change of bone mineral content (BMC) measured by single photon absorptiometry and dual photon absorptiometry. In the pulse therapy group, an oral tolerance test of 6 micrograms of 1.25(OH)2D3 was carried out to investigate its relation to long term prognosis. Furthermore, in both the pulse therapy group and PTX group, serum aluminum (A1) and delta A1 calculated by Defferoxamine (DFO) tolerance test were measured. The results are as follows. 1) In Elcitonine and Ipriflavon administration groups, increase of ALP and PTH and decrease of BMC (p less than 0.05) were recognized. 2) In the pulse therapy group, although the patients with PTH-C less than 30 ng/ml showed decrease in PTH both in short and long terms, cases with PTH-C more than 30 ng/ml kept the same level in PTH. Regardless of the change of PTH and ALP, there was no significant change observed in BMC. 3) In the PTX group, ALP/TAP ratio rose by 900% temporarily and BMC increased (p less than 0.01) in all regions measured. 4) Serum A1 and delta A1 were decreased (p less than 0.01) in PTX cases and in the pulse therapy cases in which ALP was decreased. In recent years, internal treatments on 2HPT patients have become diversified. However, exacerbation of 2HPT considered as an escape phenomenon caused the decrease in BMC after exclusive calcitonine preparatives administration. Pulse therapy, which is regarded at present as most effective in reducing PTH, ALP, did not work to increase BMC efficiently. In other word, in order to attain efficient BMC increase action, it is necessary to transfer from bone resorption phase to formative phase rapidly with drastic decrease of PTH and TAP observed in PTX.(ABSTRACT TRUNCATED AT 400 WORDS)

Dihydropteridine reductase activity: lack of association with serum aluminum levels and cognitive functioning in patients with end-stage renal disease

Although increased levels of aluminum (Al) are present in patients with dialysis encephalopathy (DE), it is unclear if the association is causal. The enzyme dihydropteridine reductase (DHPR) plays a critical role in neurotransmitter formation and its activity. Elevated levels of Al are reported to decrease DHPR activity, which would alter neurotransmitter metabolism, thus producing DE. We examined the association between erythrocyte DHPR activity and Al levels, attention/psychomotor skills, and depression in a group of 21 patients with end-stage renal disease. DHPR activity was not related to Al level, mental status, psychomotor ability, or depression score. After administration of deferoxamine (an Al chelating agent), Al level increased significantly but DHPR activity remained the same. Our results suggest that the mechanism for the development for DE does not involve alterations of neurotransmitter metabolism caused by Al-mediated reductions in DHPR activity.

Calcium metabolism in children during long-term total parenteral nutrition: the influence of calcium, phosphorus, and vitamin D intakes

Hypercalciuria and bone disease are frequently associated with total parenteral nutrition (TPN) in children and adults. The aim of this study was to assess the influence of calcium, phosphorus, and vitamin D intakes on hypercalciuria. We observed seven children aged 4-13 years receiving home cyclic TPN for 4 consecutive years. Calcium and phosphorus intakes, constant during the 1st year, were reduced during the last 3 years to 50 and 30% of the initial intakes, and vitamin D was stopped during the 3rd and the 4th years. All children had hypercalciuria and one of them had acute painful osteopenia and nephrocalcinosis at the beginning of the study. Hypercalciuria was corrected and painful bone disease did not occur during the three following years, with TPN daily intakes of calcium, 0.35 mmol/kg, and phosphorus, 0.70 mmol/kg. Cessation of vitamin D administration during 48 months led to no further decrease in calciuria nor to the occurrence of clinical or biological signs of vitamin D deficiency. However, we hypothesize that excessive vitamin D intake may have facilitated the occurrence of the TPN-related bone disease in one patient and should be avoided. The possible role of parenteral aluminum loading is also discussed.

Determination of aluminum in the human serum of a dialysis patient by ion-pair reversed-phase partition high-performance liquid chromatography

An ion-pair reversed-phase partition high-performance liquid chromatography-spectrophotometric method is described for the determination of aluminum in human serum, based on its complexation with 2,2'-dihydroxyazobenzene. The chelate is separated on C18-bonded silica packing by using an aqueous methanol mobile phase containing tetrabutylammonium bromide and is detected with 0.005 AU full-scale at 510 nm. The proposed system offers a simple, sensitive, and selective method. The detection limits defined as twice the standard deviation of the blank signal, are 0.2 micrograms L-1 in pure solution and 6 micrograms L-1 in serum. The sample solution is prepared from 0.4 mL of serum after protein precipitation with hydrochloric acid and methanol. There was good agreement between the values obtained by this method and graphite furnace atomic absorption spectrophotometry. The aluminum concentrations in 121 patients on hemodialysis were 6-201 micrograms L-1.

Aluminum-citrate interaction in end-stage renal disease

The influence of a sodium citrate/citric acid mixture on the gastrointestinal (GI) absorption of aluminum (Al) from an Al(OH)3 preparation was evaluated in six stable maintenance hemodialysis patients. Plasma Al concentrations were determined serially after each of the following treatment sequences (I) Al(OH)3; (II) Al(OH)3 + sodium citrate/citric acid; (III) sodium citrate/citric acid; (IV) Al(OH)3 + NaHCO3. AUC0-8 for plasma Al from 0 to 8 hours was significantly greater (p less than 0.05) for Al(OH)3 + sodium citrate/citric acid (73 +/- 23 micrograms.hr/l; mean +/- SEM) than Al(OH)3 (16 +/- 30 micrograms.hr/l); sodium citrate/citric acid (-27 +/- 14 micrograms.hr/l); or Al(OH)3 + NaHCO3 (6 +/- 22 micrograms.hr/l). The 24 hour Al level remained above baseline (p less than 0.03) following Al(OH)3 + sodium citrate/citric acid (31 +/- 12 (pre) vs 54 +/- 14 micrograms/l (post), in contradistinction to study limb: l (34 +/- 14 vs 30 +/- 12 micrograms/l); III (79 +/- 40 vs 65 +/- 35 micrograms/l); and IV (71 +/- 37 vs 66 +/- 42 micrograms/l). We conclude that the GI absorption of Al from Al(OH)3 is enhanced by citrate in patients undergoing hemodialysis and that elevations of plasma Al persist longer. The concomitant administration of citrate and Al-containing phosphate (PO4) binders should be avoided in patients with end-stage renal disease (ESRD). NaHCO3 may serve as an alternative therapy for metabolic acidosis with less risk of enhancing Al absorption.

Effect of calcitriol infusions on serum aluminum in vitamin D-depleted rabbits fed an aluminum-supplemented ration

Three dosages of calcitriol (10, 30 and 60 IU/day) were given to rabbits by subcutaneously implanted osmotic pumps. The purpose was to compare the dosages with regard to their putative effect in elevating serum aluminum levels by mechanisms such as enhancing intestinal absorption, diminishing renal excretion, or others. To establish uniform levels of endogenous calcitriol and its precursors, all rabbits had been depleted of vitamin D. The depletion was demonstrated by their serum calcidiol and calcitriol levels declining to unmeasurable levels, following the regimen of a vitamin D-free diet. The 8 rabbits were then placed on an aluminum-supplemented (aluminum lactate) ration. The amount of feed (and aluminum) consumed was determined at daily intervals. Serum aluminum levels were determined at intervals during the 7 days on this regimen. In a second test, the same 8 rabbits received the same regimen but in addition were infused with 10, 30 or 60 IU calcitriol per day. It was found that the aluminum-fed rabbits receiving 60 IU/day and 30 IU/day calcitriol infusions showed statistically significantly elevated serum aluminum levels as compared to their levels without calcitriol (p = 0.0208 and p = 0.434, respectively). Rabbits receiving pumps delivering 10 IU/day while receiving the aluminum-supplemented ration showed no rise in serum aluminum with time or treatment during the 7 day study. Likewise rabbits receiving aluminum-supplemented rations without calcitriol showed only an early minimal rise in mean serum aluminum which returned to the pre-test level by the end of a week in spite of continued consumption of aluminum-supplemented rations.

Short report: plasma aluminium concentration and 24-hour urinary aluminium excretion before, during and after treatment with sucralfate

Ten dyspeptic patients were treated with 1 g sucralfate q.d.s. for six weeks. The plasma aluminium concentration and 24-h urinary aluminium excretion were measured at 3-weekly intervals before, during and after treatment with sucralfate. Compared with before treatment, there were significant rises in the median plasma aluminium concentration at 3 and 6 weeks during treatment with sucralfate (6 micrograms/L to 13 and 12 micrograms/L). The median 24-h urinary aluminium excretion rose significantly from a pretreatment level of 20 micrograms to 71 and 78 micrograms after 3 and 6 weeks of treatment; the significant increase of urinary aluminium excretion persisted for three weeks after cessation of treatment (52 micrograms/24 hours), but thereafter urinary excretion was not significantly different from pretreatment. The results are consistent with significant absorption and tissue accumulation of aluminium during standard treatment with sucralfate in individuals with normal renal function.

[Rheumatologic and radiologic symptoms of secondary hyperparathyroidism: retrospective long-term study of 175 chronic hemodialysis patients]

Despite recent improvements of hemodialysis (HD) techniques, symptoms due to secondary hyperparathyroidism (HPT) contribute to longtime complications of HD patients. The aim of the present retrospective study was to determine the incidence and localization of radiological joint and bone lesions in 175 patients on chronic HD. In 108 patients the diagnosis of HPT was made by radiologic criteria. 56% had radiomorphologic lesions of the hands, 45% of the acromio-clavicular (AC) joint, 31% of the shoulder, and 27% of the pelvis. No sex difference was found for prevalence of HPT in these patients, nor was one found for any of the underlying renal diseases. There was a negative correlation between elevated serum parathyroid hormone and serum aluminum concentrations. In 111 patients the history of bone and joint pain was evaluated. 54% of these patients suffered from bone pain, arthralgia, and morning stiffness. Radiological lesions of AC-joint correlated with shoulder pain in 38%. Our data show that even in the predialytic phase of renal insufficiency x-rays of the shoulder are helpful in early diagnosis of HPT. Skeletal manifestations specific for one of the underlying renal diseases do not exist. Elevated PTH levels are a good indicator of HPT in these patients, whereas low levels of PTH do not exclude radiological manifestations. In contrast to beta 2-microglobulin amyloidosis, pain does not occur during rest and is not worsened during HD. Treatment with non-steroidal antiinflammatory drugs led to pain relief in the majority of patients. Pain history in patients on chronic HD provides important information concerning the differential diagnosis of HPT/beta 2-microglobulin amyloidosis.

Deposition of aluminium in tissues of rabbits exposed to inhalation of low concentrations of Al2O3 dust

With strong evidence coming to light for the toxicity of aluminium (Al), especially to the brain, investigation into the effects of inhalation of low concentrations of Al dust in animal models has become important. This study follows up previous observations on the effects of Al on the concentrations of essential metals in serum of workers exposed to inhalation of low concentrations of Al dust, with a study of the concentrations of Al in tissues of rabbits exposed to Al dust at one twentieth of the threshold limit value (TLV). Even at this low concentration, the amount of Al in the brains of these animals was nearly two and a half times as high as that of the control animals. The concentrations in other tissues were similar to normal. At the same time, the concentrations of Al in the serum was only slightly raised, indicating that this variable is a poor marker for the effects of Al on the body. It is suggested that an extensive study is needed to determine a more correct TLV and health based permissible concentration for occupational exposure to Al.

Aluminium absorption in infancy

The use of aluminium-containing medications and aluminium contamination of infant formulae is common. We aimed to determine whether aluminium absorption occurs after antacid ingestion. Plasma and urinary levels of aluminium were measured before and after antacid therapy in seven infants whose mean gestational age was 36 +/- 2 weeks and postnatal age 11 +/- 5 days. Antacid therapy (400-800 mumol aluminium) was given with feeds for 2 days. Plasma aluminium levels increased and reached toxic levels (0.64 +/- 0.33 mumol/L vs 3.48 +/- 2.86 mumol/L, P = 0.029). Urinary aluminium: creatinine ratio also increased. These results demonstrate that infants absorb aluminium from antacids and raise the concern of aluminium toxicity.

Calcium citrate markedly enhances aluminum absorption from aluminum hydroxide

The effect of calcium citrate on intestinal aluminum absorption, assessed by the increment in urinary aluminum excretion, was evaluated in eight normal men. Baseline urinary aluminum excretion was determined for 2 days; thereafter, subjects ingested aluminum hydroxide for 3 days. In a cross-over study, subjects were given either calcium citrate, 950 mg four times a day, or placebo during the 3 days of aluminum hydroxide ingestion (2.4 g/d). Plasma aluminum levels were measured on the second control day and the third day of aluminum hydroxide ingestion. Baseline urinary aluminum excretion was 0.02 +/- 0.004 (6.5 +/- 1.1 micrograms/g creatinine) and 0.03 +/- 0.005 mumol/mmol creatinine (7.4 +/- 1.3 micrograms/g creatinine). These values increased during aluminum hydroxide therapy, but values were much greater when calcium citrate was ingested with aluminum hydroxide. On 3 consecutive days, urinary aluminum excretion levels were 11.1 +/- 3.23, 8.8 +/- 2.9, and 5.3 +/- 0.7 times greater during the administration of calcium citrate with aluminum hydroxide than with aluminum hydroxide alone. Plasma aluminum levels did not differ in the two treatment groups. Thus, calcium citrate markedly enhances the absorption of aluminum from aluminum hydroxide and the two must not be prescribed together in patients with renal failure.

High serum aluminium levels and acute reversible encephalopathy in a 4-year-old boy with acute renal failure

We report a 4-year-old boy, in acute renal failure, who had acute encephalopathy with very high serum aluminium levels (135 micrograms/l [5 mumol/l]) after receiving vesical irrigations with alum. We believe that in situations of non-focal neurological deterioration with no apparent cause in patients with impaired renal function receiving aluminium-containing preparations, the possibility of acute aluminium poisoning should be considered.

Removal of silicon, aluminum and beta 2-microglobulin in chronic haemodialysis patients

One hundred outpatients on chronic haemodialysis with polymethylmethacrylate (PMMA) membrane dialyzer were randomly chosen. A control group of 100 likewise randomly chosen outpatients were treated with cuprophane membrane dialyzer. In both groups the treatments lasted for one year. Comparison of the test results revealed that Si, Al and beta 2-M.G levels could be reduced in patients on chronic HD with PMMA.

Calcium acetate control of serum phosphorus in hemodialysis patients

Calcium acetate has many characteristics of an ideal phosphorus binder. It is a readily soluble salt that avidly binds phosphorus in vitro at pH 5 and above. One-dose/one-meal balance studies show it to be more potent than calcium carbonate or calcium citrate. We studied chronic (3-month) phosphorus binding with calcium acetate in 91 hyperphosphatemic dialysis patients at four different centers. All phosphorus binders were stopped for 2 weeks. Calcium acetate at an initial dose of 8.11 mmol (325 mg Ca2+) per meal was then used as the only phosphorus binder. Dose was adjusted to attempt control of predialysis phosphorus level less than 1.78 mmol/L (5.5 mg/100 mL). Final calcium acetate dose was 14.6 mmol (586 mg) Ca2+ per meal. Sixteen patients developed mild transient hypercalcemia (mean, 2.84 mmol/L [11.4 mg/dL]. Initial phosphorus values in mmol/L (mg/dL) were 2.39 (7.4); at 1 month, 1.91 (5.9); and at 3 months, 1.68 (5.2). Initial calcium values in mmol/L (mg/dL) were 2.22 (8.9); at 1 month, 2.37 (9.5); and at 3 months, 2.42 (9.7). Initial aluminum values in mumol/L (micrograms/L) were 2.99 (80.7); and at 3 months were 2.54 (68.4). Initial C-terminal parathyroid hormone (C-PTH) values in ng/mL were 14.6; at 1 month, 11.9; and at 3 months, 13.2. Sixty-nine patients then entered a double-blind study. Phosphorus binders were stopped for 1 week. Calcium acetate (at a dose established in a prior study) or placebo was then administered for 2 weeks. Next, patients were crossed to the opposite regimen for 2 weeks. Initial phosphorus was 2.36 mmol/L (7.3 mg/100 mL) and calcium 2.22 mmol/L (8.9 mg/100 mL).(ABSTRACT TRUNCATED AT 250 WORDS)