1-alpha-Hydroxyvitamin D3 derivatives in the treatment of renal bone diseases: justification and optimal modalities of administration

The use of 1 alpha-hydroxyvitamin D3 [1 alpha(OH)D3] derivatives in a uremic patient is justified only in the treatment of hyperparathyroidism (i.e. when plasma intact parathyroid hormone - PTH - levels are above five or three times the upper limit of normal according to whether the patient is on continuous ambulatory peritoneal dialysis or on hemodialysis and between 0.5-1.5, 1-2 and 2-3 times the upper limit of normal for a creatinine clearance of, respectively, 30, between 30 and 10, or below 10 ml/min/1.73 m2). The following prerequisites have however to be satisfied: (1) a good vitamin D3 repletion should be secured by plasma 25(OH(D) levels of 20-30 ng/ml (if necessary by administration of native vitamin D or 25(OH)D3), and (2) phosphate retention (which is aggravated by the increased phosphate intestinal absorption induced by the 1 alpha (OH)D derivatives) and the consequent possible hyperphosphatemia should be prevented or corrected by the oral administration of alkaline salts of calcium given before the meals as phosphate binders without inducing hypercalcemia. These prerequisites explain the narrow therapeutical margin of 1 alpha (OH)D3 derivatives in uremic patients before dialysis (more so in the adult than in the child) and the possible broadening of this margin in the patients on dialysis by the use of low dialysate calcium concentrations (1.25-1.00 mmol/l) in order to prevent hypercalcemia by inducing a negative perdialytic calcium balance. Once hyperphosphatemia is prevented by oral calcium, 1 alpha (OH)D3 derivatives have the advantage to suppress the transcription of the prepro PTH gene by a mechanism independent of an increase in plasma calcium. Controlled randomized trials have not confirmed the claimed advantage in efficacy and safety of the parenteral versus the oral route nor of the intermittent versus the daily mode of their administration. The advantages of using the so called 'nonhypercalcemic hyperphosphatemic' vitamin D3 derivatives in combination with oral calcium over 1 alpha(OH)D3 derivatives in the treatment of uremic hyperparathyroidism are still waiting for clinical demonstration. Vitamin D derivatives have no place in the treatment of aluminic bone diseases which necessitate long term deferoxamine treatment and prevention of aluminum exposure by the dialysate and the phosphate binders. They are not indicated in the treatment of 'idiopathic' adynamic bone disease which is due to uremia per se combined with an excessive PTH suppression for the degree of renal failure. This low bone turnover pattern is associated with an increased risk of hypercalcemia and hyperphosphatemia and necessitates only a stimulation of PTH secretion by inducing a negative calcium balance with a lower dialysate calcium concentration or simply by discontinuing the oral calcium supplement in the uremic patient not yet dialyzed. In rare cases this pattern is due to a granulomatosis and is corrected by prednisone.

Management of hyperphosphatemia in patients with renal failure

Phosphate retention plays a major role in the pathogenesis of hyperparathyroidism at all stages of renal insufficiency. Dietary phosphate restriction is mandatory only for adults and is not advised for children because of the recommended diet allowance. Dietary restriction is usually not sufficient, and phosphate binders are almost always necessary when the glomerular filtration rate falls below 40 mL/min. Because long-term administration of aluminum phosphate binders is associated with risk of aluminum intoxication despite the use of so-called "safe doses", alternative phosphate binders should be used. Magnesium hydroxide and carbonate can be used only for dialysis patients because a low dialysate magnesium concentration is necessary to prevent the hazards of hypermagnesemia. Therefore, the major alternative is the use of alkaline salts of calcium. The most recently proposed salt, acetate, has a higher phosphate-binding capacity than carbonate but exposes patients to the same incidence of hypercalcemia despite the use of half the dose of elemental calcium. These salts should be taken with meals in order to complex more dietary phosphate and decrease calcium absorption and therefore the risk of hypercalcemia. Oral calcium alone, without 1 alpha OH-vitamin D3 derivatives, can prevent hyperphosphatemia and hyperparathyroidism in most uremic patients before dialysis and in about half of the patients dialyzed with a dialysate calcium of 1.5 to 1.65 mmol/L. 1 alpha OH-vitamin D3 derivatives, which increase intestinal absorption of phosphate, should be used only when hyperphosphatemia has been prevented by oral calcium and diet and when plasma parathyroid hormone levels increase above three times the upper limit of normal. To decrease hypercalcemic risk, patients should be given 1 alpha OH-vitamin D3 derivatives, preferably at night, as an intermittent bolus (intravenous or oral). In dialysis patients, the dialysate concentration of calcium may have to be further decreased in order to prevent hypercalcemia when high doses of oral calcium are necessary to control hyperphosphatemia.

Natriuretic and vasoactive hormones and glomerular hyperfiltration in hyperglycaemic type 2 diabetic patients: effect of insulin treatment

Evidence that an increase in plasma atrial natriuretic peptide (ANP) concentrations mediates, at least in part, glomerular hyperfiltration in diabetic rats prompted us to study the relationship between ANP and renal haemodynamics in hyperfiltering type 2 diabetic patients in association with other hormones implicated in the control of glomerular filtration rate (GFR) (catecholamines, vasopressin, renin) and in sodium tubular transport (aldosterone, ouabain-displacing factor, ODF). Since hyperglycaemia is also associated to hyperfiltration, diabetic patients who presented with secondary drug failure were studied both in hyperglycaemic and in normoglycaemic condition. For this purpose, 11 normotensive non-macroproteinuric hyperfiltering patients with type 2 diabetes were treated with an 8-day continuous insulin infusion (days 0-7). Dehydration was prevented or corrected and natriuresis was on day 0 above 100 mmol/day. The following parameters were determined on days 0 and 7: GFR and renal plasma flow (RPF) by 99mTc-DTPA and 131I-hippuran clearances; the extracellular volume, assimilated to the DTPA diffusion volume; urinary ODF by receptor-binding assay and urinary as well as plasma catecholamines by HPLC after extraction on alumin. Plasma ANP and antidiuretic hormone (ADH) were measured by radioimmunoassay after extraction on phenyl-silylsilica (ANP) and with ether (ADH). Unextracted plasma was used for radioimmunological measurement of plasma renin activity and aldosterone. When correcting hyperglycaemia to normoglycaemia GFR decreased from high to normal mean value (138 +/- 27 and 115 +/- 6 ml/min, p < 0.001), RPF followed the same trend, and the DTPA diffusion volume did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of alkaline calcium salts as phosphate binder in uremic patients

In order to prevent aluminum toxicity induced by the association of aluminum phosphate binder with 1 alpha(OH) vitamin D3 derivatives and the use of deferoxamine with its own hazards to diagnose and treat this toxicity, we have shown in 1982 that it was possible to replace the iatrogenic association of aluminum phosphate binder with 1 alpha OH vitamin D derivatives by oral calcium carbonate taken with the meals in order to bind phosphate and correct the negative calcium balance. This led to the disappearance of the crippling aluminic osteomalacia and adynamic bone diseases in our center. The effectiveness of CaCO3 without 1 alpha(OH)D3 derivatives in the control of hyperparathyroidism in dialysis patients has been proven by the appearance in four patients of our dialysis population of an histological idiopathic adynamic bone disease associated with relative hypoparathyroidism, and by the finding that more than 50% of our dialysis population treated by this sole treatment have plasma concentration of intact PTH below twice the upper limit of normal (that is, the threshold above which only significant histological osteitis fibrosa is observed). Besides the compliance problem, the limit of CaCO3 is the occurrence of hypercalcemia which occurs in about 8% of the measurements. Since calcium acetate binds twice as much phosphate for the same dose of elemental calcium as CaCO3, its use has been recommended. However, clinical experience has shown that in spite of the fact that half the dose of calcium element given as acetate does actually control predialysis plasma phosphate as well as CaCO3, the incidence of hypercalcemia is not decreased, probably because calcium availability at the alkaline pH of the intestine is much greater with Ca acetate. When hypercalcemia is frequent (and not explained by autonomized hyperparathyroidism, adynamic bone disease, overtreatment with vitamin D, granulomatosis or neoplasia) it is necessary either to decrease the dose of calcium and complete the necessary binding of phosphate by adding small doses of Mg(OH)2 or Mg carbonate, provided the dialysate Mg is decreased to 0.2 to 0.35 mmol/liter to prevent hypermagnesemia or to decrease the dialysate calcium (DCa) concentration. The decrease of DCa can be made either just when hypercalcemia occurs or on a systemic basis according to the amount of CaCO3 used and to the necessity of associating 1 alpha(OH) vitamin D3 derivatives.(ABSTRACT TRUNCATED AT 400 WORDS)

Prevention of hyperparathyroidism in patients on maintenance dialysis by intravenous 1-alpha-hydroxyvitamin D3 in association with Mg(OH)2 as sole phosphate binder. A randomized comparative study with the association CaCO3 +/- Mg(OH)2

The purpose of this study is to evaluate the place of intravenous 1 alpha-hydroxyvitamin D3 (1 alpha-OH-D3) in the prevention of radiologically obvious hyperparathyroidism (HPT) in patients on maintenance dialysis while excluding aluminium phosphate binder and using a dialysate calcium concentration of 1.62 mmol which keeps the intradialytic calcium balance neutral. Therefore, 47 patients without subperiosteal resorption and previously treated by oral CaCO3 and if necessary Mg(OH)2 as phosphate binder while their dialysate calcium had a Ca level of 1.62 and a Mg level of 0.2 mmol/l were randomized into a control group of 24 who were maintained on the same treatment and an experimental group of 23. This group discontinued CaCO3 and received intravenous 1 alpha-OH-D3 after each dialysis at increasing doses up to 4 micrograms and increased Mg(OH)2 as their sole phosphate binder. When plasma Ca increased above 2.7 mmol/l, the dose of 1 alpha-OH-D3 was decreased. When plasma PO4 increased above 2 mmol/l, the dose of Mg(OH)2 was increased to the highest dose not inducing diarrhea, hypermagnesemia (less than 2 mmol/l) or hyperkalemia (less than 6 mmol/l). In case of persistent hyperphosphatemia, the dose of 1 alpha-OH-D3 was decreased. Since mean plasma alkaline phosphatase was normal, HPT was monitored on the plasma concentration of 1-84 PTH for which a previous histological study showed that frank osteitis fibrosa was present only when they were above 70 pg/ml, i.e. (about twice the upper limit of the normal value). Before the study, plasma PTH was below this limit in 16 patients of the CaCO3 group and in 14 patients of the 1 alpha-OH-D3 group. After 6 months, they remained below this limit in all patients except 2 of each group. Plasma PTH was initially above 70 pg/ml in 8 of the CaCO3 and did not change significantly throughout the study, 2 patients having at 6 months a PTH level below 70 pg/ml. In contrast with intravenous 1 alpha-OH-D3, all the 9 patients with initial frank HPT decreased their PTH levels after 2 months, the levels being below 70 pg/ml in 6 cases. However, because of hypercalcemia and/or of hyperphosphatemia in spite of a highest tolerable dose of Mg(OH)2, 1 alpha-OH-D3 doses had to be decreased down to 0.4 microgram per dialysis at the 6th month so that at 6 months 6 of 9 patients had their PTH levels above 70 pg/ml, a number comparable to that of patients treated with CaCO3 (6 of 8).(ABSTRACT TRUNCATED AT 400 WORDS)

Control of predialytic hyperphosphatemia by oral calcium acetate and calcium carbonate. Comparable efficacy for half the dose of elemental calcium given as acetate without lower incidence of hypercalcemia

Since Mai et al. found, with the intestinal lavage technique, that the same dose of elemental calcium given as acetate (Ca Ac) complexed in the gut of uremic patients twice as much phosphate as calcium carbonate (CaCO3) while inducing a rather low calcium absorption, we wanted to see if half the dose of elemental calcium given as Ca Ac could control, on medium term, the predialysis plasma phosphate as well as CaCO3 while inducing less frequent hypercalcemia. This was evaluated in a cross-over study of 3 periods of 10 weeks according to the sequence Ca Ac, CaCO3 and Ca Ac, in 12 compliant patients on chronic dialysis previously treated by CaCO3. Because of poor tolerance of Ca Ac during the first period, 4 patients were excluded and the results were assessed only on the 8 patients who completed the study. For half the doses of elemental calcium (620 +/- 250 mg versus 1,310 +/- 560 mg versus 710 +/- 200 mg/day), Ca Ac allowed the same control of predialytic hyperphosphatemia (1.67 +/- 0.34; 1.74 +/- 0.32; 1.75 +/- 0.38) with paradoxically comparable normal mean plasma calcium concentration (2.61 +/- 0.14; 2.56 +/- 0.13; 2.55 +/- 0.14 mmol/l). Plasma alkaline phosphatases and intact PTH concentrations remained also stable during the 3 periods. The frequency of hypercalcemia greater than 2.75 mmol/l (12; 9; 20%) and of hyperphosphatemia greater than 2 mmol/l (17; 22; 27%) were comparable with the 2 treatments. In conclusion, Ca Ac controls predialytic hyperphosphatemia as efficiently as CaCO3 for half the dose of elemental calcium without, however, decreasing the frequency of hypercalcemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-aluminic adynamic bone disease in non-dialyzed uremic patients: a new type of osteopathy due to overtreatment?

Adynamic bone disease, characterized by a low bone formation rate with normal or reduced amount of unmineralized osteoid, is supposed to be the consequence of aluminum intoxication in uremic patients. However, the emergence of adynamic bone disease has been recently reported in hemodialyzed patients in the total absence of aluminum overload. This study was aimed to assess whether such a histological pattern of adynamic bone disease was already present in uremic patients not yet on dialysis. Twenty-seven asymptomatic uremic patients (mean age +/- SD 43 +/- 10 years, mean creatinine clearance 19 +/- 3 ml/mm) were studied and bone biopsies were repeated in 16 of them after 18 +/- 10 months of treatment with oral calcium carbonate (1-3 g of elemental calcium/day) and calcidiol (21 +/- 14 micrograms/day). None of the patients received aluminum hydroxide, and the search for bone aluminum deposits was negative in all patients both before and after treatment. Two patients fulfilled the criteria of adynamic bone disease on their post-treatment biopsies. They originated from patients classified as having normal bone histology before treatment. Comparison with the other patients showed that they had comparable plasma C-terminal PTH but higher plasma creatinine than patients with normal bone histology and lower plasma C-terminal PTH than patients with osteitis fibrosa but comparable plasma creatinine. The plasma levels of 1,25(OH)2D reached values above normal after treatment in these two patients. It is suggested that adynamic bone disease not related to aluminum intoxication can develop in uremic patients independently of dialysis, and is favored by a relative hypoparathyroidism for the degree of renal failure, possibly induced by elevated plasma concentrations of calcitriol.

Atrial natriuretic factor in pregnancy and pregnancy-induced hypertension

In normal pregnancy, cross-sectional clinical data do not consistently show plasma ANF concentration differences between early pregnancy and the nonpregnant state. Sequential data in the baboon (but not in rat) show a significant decrease in plasma ANF concentration and in cardiac filling pressures in early pregnancy. The latter data support the view that pregnancy is an underfill state secondary to a primary vasodilatation. Cross-sectional and longitudinal studies in normal pregnancy in humans show that plasma ANF levels tend rise to values that are, in the third trimester, higher than in the nonpregnant state. However, late postpartum sequential data (1.5-3 months) in humans do now show a significant drop in plasma ANF concentrations, suggesting that plasma ANF is not actually increased in normal pregnancy. In the baboon (but not in the rat) there is a steady rise in plasma ANF levels to values that are significantly higher in third trimester than before pregnancy. These data suggest that in human pregnancy, in contrast with the baboon, the plasma volume expansion induced by normal pregnancy is not sensed as such by the atria probably because of an isopressive adaptation of plasma volume to an enlarged vascular bed. However, acute decrease or increase of venous return induced by low sodium diet, changing position or infusion of isotonic saline are sensed as such by the atria in normal pregnancy as in the nonpregnant state.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of single-dose intravenous, oral, and intraperitoneal pefloxacin in patients on chronic ambulatory peritoneal dialysis

Comparison of plasma and dialysate concentrations of pefloxacin after intravenous, oral, or intraperitoneal administration shows excellent bidirectional diffusion of the quinolone through the peritoneal membrane, demonstrating that therapeutical concentrations can be achieved in the dialysate after intravenous or oral administration. In this study, the half-life of the drug was 18.8 +/- 1.4 h, i.e., apparently longer than that reported for normal controls or uremic patients on hemodialysis.

Diet, vitamin D and vertebral mineral density in hypercalciuric calcium stone formers

To elucidate the pathophysiology of dietary calcium independent hypercalciuria, 42 calcium stone formers (Ca SF) were selected because they had on free diet a calciuria greater than 0.1 mmol/kg/day. For four days they were put on a diet restricted in calcium (Ca RD) by exclusion of the dairy products. They collected 24 hour urines on free diet and on day 4 of Ca RD as well as the two-hour fasting urines on the morning of the day 5 and the four-hour urines passed after an oral calcium load of 1 g, for measurement of creatinine, Ca, PO4, urea and total hydroxyprolinuria (THP). On day 5 fasting plasma concentrations of Ca, PO4, intact PTH, Gla protein, calcidiol and calcitriol were measured. The patients were firstly classified into dietary hypercalciuria (DH, 18 patients) and dietary calcium-independent hypercalciuria (IH, 24 patients) on the basis of the disappearance or not of hypercalciuria on Ca RD. Then the patients with IH were subclassified into absorptive hypercalciuria (AH) because of normal fasting calciuria (8 patients) and into fasting hypercalciuria (16 patients). Fasting hypercalciuric patients were subsequently divided according to the PTH levels into renal hypercalciuria (RH, 1 patient) with elevated fasting PTH becoming normal after the Ca load and undetermined hypercalciuria (UH, 15 patients) with normal PTH levels. Furthermore, their vertebral mineral density (VMD) was measured by quantitative computerized tomography which was normal in DH (91 +/- 6% of the normal mean for age and sex) but was decreased in IH to 69 +/- 4%. No difference in VMD was observed between AH and UH. Urinary excretions of urea, phosphate and THP was higher in IH than in DH and comparable in AH and UH. Sodium excretion Ca RD was the same in all groups and subgroups as well as the plasma parameters. Plasma calcitriol was increased in IH and DH comparatively to normal in spite of normal plasma calcidiol. Calciuria increase after oral calcium load, an index of Ca absorption, was higher in IH than in controls and comparable in IH and DH as well as in the three subgroups of IH. From these data and correlation studies in IH it is concluded: (1.) VMD is decreased in Ca stone formers with IH but not in those with DH, making the distinction of these two groups of hypercalciuria patients clinically relevant.(ABSTRACT TRUNCATED AT 400 WORDS)

Pancreatitis related to severe acute hypertriglyceridemia during pregnancy: treatment with lipoprotein apheresis

We report a clinical observation of acute pancreatitis due to severe hypertriglyceridemia in a pregnant woman. In order to decrease the serum triglyceride level rapidly, two lipaphereses were undertaken using the double-filtration technique. This lipoprotein apheresis technique is briefly described and the efficacy in reducing rapidly hypertriglyceridemia is outlined. Like in 3 previously published reports, the patient had a rapid recovery, confirming that lipoprotein apheresis should be an adequate and a well-tolerated treatment in such a condition.

A case of pseudo-Nelson's syndrome: cure of ACTH hypersecretion by removal of a bronchial carcinoid tumor responsible for Cushing's syndrome

It may sometimes be difficult to distinguish Cushing's disease from ectopic ACTH syndrome. A case is described here of a patient with a Cushing's syndrome and diagnostic difficulties. Initial features were consistent with a Cushing's disease (in particular metopirone test was positive). Because of relapse of hypercortisolism after mitotane therapy, total adrenalectomy was performed. Thereafter features occurred that evoked Nelson's syndrome, including high plasma ACTH levels and a pituitary mass syndrome. Pituitary reserve testings by vasopressin or corticotropin-releasing factor were positive, although inconstantly, in that plasma ACTH increased. A lung tumor was discovered about 20 yr after the first clinical signs of hypercortisolism. Its removal led to the discovery of a bronchial carcinoid tumor and was followed by normalization of plasma ACTH levels. An analysis of proopiomelanocortin-related peptides was performed postoperatively on the blood drawn before and after the tumor resection and on the tumor; the results of this study would have been contributive to the diagnosis of occult ectopic ACTH tumor. In conclusion this case demonstrates the limitations of the conventional procedures in the diagnosis of the ectopic ACTH syndrome. At contrast the newer biochemical procedures may be very useful in determining the type of hypercortisolism.

Plasma atrial natriuretic factor and urinary excretion of a ouabain displacing factor and dopamine in normotensive pregnant women before and after delivery

Estimation of urinary excretion of a ouabain displacing factor and dopamine was carried out immediately before delivery, and 7 days and 70 to 90 days after delivery in 12 normotensive pregnant women. Simultaneous estimation of plasma 99-126 atrial natriuretic factor, plasma renin activity, and plasma aldosterone were also undertaken. The data were compared with those obtained in a group of nonpregnant normotensive women (n = 14) and a group of pregnant normotensive women in the early phase of the third trimester (n = 14). Urinary ouabain displacing factor and dopamine levels were significantly higher in the early phase of the third trimester, as compared with nonpregnant women. But immediately before delivery, ouabain displacing factor excretion had fallen below nonpregnant values and dopamine excretion had dropped to control values. Both remained low after delivery. Plasma atrial natriuretic factor was higher in pregnant women, as compared with nonpregnant controls and remained high just before delivery and 7 and 70 to 90 days after delivery. Plasma renin activity and plasma aldosterone levels were higher during pregnancy and had fallen to nonpregnant values 7 days post partum. This drop in plasma renin activity and aldosterone by 7 days post partum, in contrast with the unchanged high values of atrial natriuretic factor, may contribute to negative sodium balance after delivery. It is concluded that there is considerable discrepancy in natriuretic and antinatriuretic factors before and after delivery.

[Mixed cryoglobulinemia]

Mixed cryoglobulinemia are divided in two types: type II is the association of polyclonal IgG and a monoclonal IgM and type III is the association of polyclonal IgG and polyclonal IgM. In 70 p. 100 of cryoglobulinemia, a cause may be found (hematologic, auto immune disorder, infections, hepatic disorders), in some cases the recognition of the cause is delayed. In 30 p. 100 of cases, no cause can be identified and the cryoglobulinemia is considered as essential. Main clinical finding are purpuric skin rash, urticaria, arthralgia, motor sensitive polyneuropathy, diffuse proliferative glomerulo nephritis. Biological signs associate anemia, rheumatoïd factor and hypocomplementemia. Mixed essential cryoglobulinemia (the Meltzer and Franklin syndrome) is characterized by a systemic vasculitis involving small and middle size vessels.

Hemodialysis in the treatment of lactic acidosis in diabetics treated by metformin: a study of metformin elimination

The aim of this study was to determine the characteristics of metformin elimination by dialysis. For this purpose we report the kinetic parameters during dialysis and the metformin clearance (i.e. dialysance) in four patients presenting with lactic acidosis which occurred on metformin therapy. We also studied metformin elimination in two chronically hemodialyzed diabetic patients inadvertently maintained on metformin therapy and in two chronically hemodialyzed non-diabetic patients who took a single dose of metformin before a dialysis session. Analysis of plasma concentration-time curves showed a biphasic pattern of metformin - elimination, according to a two-compartment model. We demonstrate that metformin may be removed even after reaching an equilibrium between blood and dialysate levels in a recirculating system, suggesting a storage of metformin in a deep compartment with a gradient of concentration between this compartment and the blood. Lastly, metformin dialysance appears satisfactory (68 ml/min) even in the case of relatively low blood flow; this value reached 170 ml/min under good hemodynamic conditions. In conclusion, hemodialysis efficiently removes metformin and corrects metabolic acidosis in patients with metformin-induced lactic acidosis.

[Infections caused by central venous catheterization at intensive care units]

All different types of catheters can induce localized (subcutaneous) or systemic sepsis. Infection rates of 7 to 20% have been reported in the literature; catheter infection results from bacterial colonization of the skin, colonization of the line or may be secondary to blood born seeding. In a one year prospective study of 56 catheters in our unit, the rate of systemic infection was 5.3%, insertion site infection 3.6%, and contamination without infection 25%. No catheter with less than 10(2) colonies on a semi-quantitative culture method was infected. Prevention of catheter related sepsis needs strict aseptic protocols, and short duration of catheterization, antiseptic wrapping of the line; antimicrobial filtersets may further reduce the infection risk.

Indirect clinical evidence that 1 alpha OH vitamin D3 increases the intestinal absorption of aluminum

In a previous study we showed that 1 alpha OH vitamin D3 [1 alpha (OH)3] given to 16 hemodialyzed patients taking Al(OH)3 at a constant dose increased their plasma concentrations of aluminum [Demontis et al. 1986]. In order to choose between 2 possible mechanisms explaining this increase (increased intestinal absorption or decreased tissue storage of aluminum), we gave, in the present study, 1 alpha (OH)3 the same dose (6 micrograms per week) for the same period (4 weeks) to 15 stable hemodialyzed patients after their Al(OH)3 had been discontinued for 6 weeks. Under Al(OH)3 treatment they had a mean plasma aluminum (2.33 +/- 2.36 mumol/l) which was not significantly different from that of the patients in our former study (1.23 +/- 0.25 mumol/l). After Al(OH)3 discontinuation, plasma aluminum (measured by inductively coupled plasma emission spectrometry) decreased significantly as early as the 2nd week of the control period (1.39 mumol/l). The decrease was maintained at a plateau throughout the 5 weeks of the control period (1.38 mumol/l), the 4 weeks of 1 alpha OH vitamin (vit) D3 administration (1.40 mumol/l) and the 8 weeks of the post 1 alpha (OH)3 period (1.22 mumol/l). Plasma calcium and phosphate concentrations increased significantly with 1 alpha (OH)3 and decreased thereafter whereas plasma PTH concentrations decreased during 1 alpha (OH)2 D3 and increased after its discontinuation suggesting biological activity of 1 alpha (OH)3. Since 1 alpha (OH)3 increases plasma aluminum in hemodialyzed patients only when they are simultaneously taking Al(OH)3, it is suggested that this increase is explained by an increase of intestinal absorption of aluminum and not by a tissue redistribution of aluminum.

Disappearance of aluminic bone disease in a long term asymptomatic dialysis population restricting A1(OH)3 intake: emergence of an idiopathic adynamic bone disease not related to aluminum

In dialysis centers using reverse osmosis-treated water but not restricting A1(OH)3 administration, a high prevalence of histological aluminum bone disease has been reported. To assess whether this is also the case in our center where A1(OH)3 intake has always been restricted and even completely given up after 1980 thanks to high doses of CaCO3, we reviewed 42 bone biopsies performed between 1975 and 1985 in patients dialyzed for a mean duration of 56 months. Seventeen of these patients had been dialyzed before 1978 with softened water moderately contamined by aluminum, 15 had always been dialyzed with reverse osmosis-treated water and 10 had been exclusively treated by hemofiltration. The prevalence of aluminum bone disease in the whole population was 9.5% (4 patients) and consisted only of adynamic bone disease, osteomalacia being totally absent. When the patients dialyzed with aluminum-contaminated water were excluded as well as 1 diabetic patient who had taken A1(OH)3 for 1.5 years the prevalence of aluminum bone disease was null in this population. When the whole population is considered the prevalence of the other types of bone disease was 76% for osteitis fibrosa and 14.5% for a non-aluminic adynamic bone disease (6 cases). These latter cases differed from the osteitis fibrosa group only by a relative hypoparathyroidism not explained by higher plasma concentrations and higher oral cumulative doses of calcium, magnesium and aluminum or by lower plasma concentrations of phosphate and bicarbonate. None had previous parathyroidectomy, one had an unsuccessful transplantation and one was diabetic. Iron overload was excluded by negative Perls staining.(ABSTRACT TRUNCATED AT 250 WORDS)