Aluminum associated bone disease: clinico-pathologic correlation

Newcastle Bone Disease in Hong Kong: A Study of Aluminium Associated Osteomalacia

We measured serum aluminium concentrations in 104 haemodialysis patients from 3 centres in Hong Kong. We found that the 52 patients dialyzed in unit A had much higher mean aluminium levels (100 μg/L) than those from the other two units (61 and 39 μg/L respectively). In unit A, where water treatment by reverse osmosis had been introduced only recently, 30.8% of patients had fractures/looser zones, 46.2% had rugger-jersey spine and 28.8% had skeletal erosions. When these patients were divided into two groups according to whether their serum aluminium concentration was below or above 100 μg/l, the latter patients had significantly lower alkaline phosphatase, serum phosphate, and higher total prescribed dose of aluminium hydroxide. It was concluded that both dialysate aluminium and oral aluminium intake seemed to have contributed to the high incidence of osteomalacic fractures among Unit A patients. In eight of these patients serum aluminium increased by more than 150 μg/L after four weeks of receiving 1.5 g desferrioxamine twice weekly. Serial X-rays showed that the mean time after dialysis for the appearance of fractures/Looser zones was 72 months. Three patients developed fractures/Looser zones after successful renal transplantation; and it was postulated that the prompt excretion of aluminium permitted increased osteoclastic activity, resulting in fractures in these patients.

The spectrum of bone disease in 200 chronic hemodialysis patients: a correlation between clinical, biochemical and histological findings

INTRODUCTION

Renal osteodystrophy includes the complete range of mineral metabolism disorders that affect the skeleton in patients with chronic renal failure.

PATIENTS AND METHODS

200 patients with end-stage renal disease and on dialysis were investigated regarding the clinical, biochemical and histological findings of bone disease.

RESULTS

The spectrum of renal osteodystrophy consisted mainly of high turnover bone lesions (74.5%), including osteitis fibrosa in 57.5%. Patients with mild bone disease were on dialysis for shorter periods of time and were mostly asymptomatic. Patients with aluminum-related bone disease (16.5%) had the greatest aluminum exposure, either orally or parenterally, and together with patients with high turnover mixed disease, were the most symptomatic. Although on a non-regular basis, the vast majority of the patients (82.5%) had been receiving vitamin D. The incidence of adynamic bone disease was high (n = 8) among parathyroidectomized patients (n = 12). Significantly higher serum levels of alkaline phosphatase were observed in osteitis fibrosa.

CONCLUSIONS

The use of calcitriol and phosphate-binding agents on a non-regular basis seems to be the reason for the apparent reduced response to the treatment of secondary hyperparathyroidism. Alkaline phosphatase has been shown to be a fair marker for bone turnover in patients with osteitis fibrosa. The severity of the clinical manifestations of bone disease correlates with the histological features of bone lesion and to the time spent on dialysis.

Experimental hypophosphataemia in growing pigs: effects on endochondral ossification in comparison to osteochondrosis

Hypophosphataemia was induced in growing pigs by dietary supplementation with aluminium hydroxide. The effect on endochondral ossification was studied morphologically in comparison with normophosphataemic pigs given aluminium phosphate or left untreated. The aim of the investigation was to elucidate further the role of nutritional factors in the pathogenesis of disturbed endochondral ossification, occurring in osteochondrosis. In all pigs, focal arrestment of endochondral ossification with subsequent cartilage retention in the epiphyseal or metaphyseal growth zones was seen. In normophosphataemic pigs, focal degenerative cartilage changes were associated with impairment of vascular penetration. The lesions had morphological characteristics of early osteochondrosis. In hypophosphataemic pigs, a more generalized disturbance, endochondral ossification, was seen with impaired vascular penetration and excessive deposition of osteoid in the primary spongiosa. Focal cartilage retentions were associated with necrotic changes in the primary spongiosa and not with cartilage degeneration. The lesions were similar to rickets and it was concluded that hypophosphataemia is not an aetiological factor in the development of osteochondrosis. The differentiation between the cartilage retention seen in early stages of osteochondrosis and rickets must be based on histological examination.

Scintigraphy in the clinical evaluation of disorders of mineral and skeletal metabolism in renal failure

In patients with renal bone disease skeletal and extra-skeletal abnormalities can be visualised using conventional bone scintigraphy. Some of these abnormalities are associated with characteristic scintigraphic appearances, which are reviewed in detail, and the possible mechanisms involved are discussed. Specific imaging with iodine 123 serum amyloid P component and iodine 131 beta 2-microglobulin is also discussed in the diagnosis of beta 2-microglobulin amyloidosis specific to patients on dialysis. In the light of available evidence, it appears that bone scintigraphy plays, so far, a limited role in the clinical evaluation of skeletal and extra-skeletal abnormalities in chronic renal failure. The potential role of bone scintigraphy in identifying patients with aluminium-related bone disease needs to be investigated further, and in this respect special attention must be given to the problem of high soft-tissue activity associated with impaired renal function. Timing haemodialysis sessions before scintigraphic imaging deserves wider recognition as it reduces high soft-tissue activity, thereby allowing bone uptake to be assessed more accurately. Specific imaging of amyloidosis resulting from beta 2-microglobulin deposition is a promising technique, but the relative value of the two proposed radiopharmaceuticals needs further clarification.

Assessing the health risks of aluminum

Aluminum is a ubiquitous substance with over 4,000 uses. Aluminum, as aluminum sulfate, is commonly used in the United States as a coagulant in the treatment of drinking water. For many years aluminum was not considered to be toxic to humans. However, reports associating aluminum with several skeletal and neurological disorders in humans suggest that exposure to aluminum may pose a health hazard. In 1983 the US Environmental Protection Agency (EPA) announced plans to regulate a number of substances, including aluminum, in drinking water. Aluminum was considered because of its occurrence and apparent toxicity. Upon further evaluation of the health effects data the EPA proposed not to regulate aluminum as a result of the uncertainty of the toxicity of ingested aluminum. Putative causal associations between aluminum exposure and neurological disorders such as Alzheimer's disease have yet to be substantiated. Although several issues regarding the toxicity of ingested aluminum are unresolved, aluminum has been specified in the 1986 Amendments to the Safe Drinking Water Act, as one of 83 substances in drinking water to be regulated by 1989. Additional data are needed before the potential risk of aluminum can be assessed; therefore the EPA has deferred possible regulation until 1991.

Deferoxamine test and bone disease in dialysis patients with mild aluminum accumulation

Aluminum bone disease is a frequent complication of dialysis patients. The deferoxamine (DFO) test has been advocated as a noninvasive procedure for the diagnosis of AI bone lesion. However most of these studies have been performed in symptomatic patients with significant AI bone disease. Whether this test may provide similar data at an earlier stage of AI toxicity is not known. The present study evaluates prospectively 28 patients with mild AI load. Patients studied ranged in age from 21 to 65 years; duration of dialysis was 5.6 +/- 3.2 years; deferoxamine, 40 mg/kg body weight, was infused at the end of dialysis. Serum AI was measured before DFO administration and before the next dialysis treatment. Bone biopsies were performed in all patients. Cortical bone AI was determined biochemically; trabecular and cortical bone AI were also determined histochemically. Mean basal serum AI (43.2 +/- 30.8 micrograms/L) and cortical bone AI (25.7 +/- 35.2 micrograms/g) were moderately increased. Basal serum AI correlated (r = 0.77) with the increment in serum AI after DFO infusion. After DFO, stainable trabecular and cortical bone AI correlated in a similar manner with both basal serum AI and increment in serum AI. Only biochemically determined cortical bone AI was not significantly related to basal serum AI. Nineteen of the 28 patients had evidence of osteitis fibrosa on bone biopsy. Stained AI surfaces but not trabecular AI were different in patients with low and patients with high bone formation rates. The bone findings, assessed as bone formation rates and resorption surfaces, did not correlate with biochemically or histochemically determined bone AI.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of early parathyroidectomy on aluminum-induced rickets in growing uremic rats

Rats were subjected to a two-stage 5/6 nephrectomy and treated with aluminum for 2 and 4 weeks with a cumulative dose of 4.2 and 8.4 mg of aluminum, respectively. Other animals were parathyroidectomized and loaded with 8.4 mg of aluminum for 4 weeks. Histomorphometry and electron microscopy (tibiae), aluminum tissue (bone, kidney, liver) determination, serum (Ca, Mg, Zn, P, urea, creatinine, alkaline phosphatase, 1,25(OH)2D3, PTH) and urine (creatinine, A1) revealed that: (a) a dose of 8.4 mg aluminum was sufficient to induce rickets within 4 weeks of treatment and was associated with decreased serum calcitriol values and high aluminum accumulation within organs (electron-dense material was found in osteoblasts only); (b) previous parathyroidectomy prevented the occurrence of any aluminum-induced alteration of bone. It was associated with higher calcitriol and phosphorus values than in corresponding non-parathyroidectomized rats and significantly reduced aluminum accumulation within organs. The results was influenced neither by a drop in serum calcium values nor by different degrees of renal failure. We suggest that aluminum-induced rickets in growing uremic rats is prevented or delayed when previous parathyroidectomy has been performed.

Plasma aluminum levels (unstimulated and stimulated): clinical and biochemical findings in 185 patients undergoing chronic hemodialysis for 4 to 95 months

Plasma aluminum levels (unstimulated and stimulated by deferoxamine infusion), along with signs and symptoms associated with aluminum overload, were evaluated in 185 patients (97 men, 88 women; mean age, 58 +/- 8 years) who had been undergoing dialysis for 4 to 95 months and who were still receiving treatment in 1985 at a free-standing dialysis facility which has always used water purified by reverse osmosis. Monthly water aluminum levels never exceeded 15 micrograms/L; therefore, the major source of aluminum in these patients was oral phosphate binders. Unstimulated plasma aluminum levels ranged from 7 to 392 micrograms/L, averaged 81.5 +/- 56.4, and did not correlate with the duration of dialysis (r = 0.07; P greater than 0.31) or frequency of symptoms. Stimulated plasma aluminum levels increased in a linear fashion (r = 0.57; P less than 0.0001) with time on dialysis; however, there was no statistical association between the stimulated aluminum levels and a variety of nonspecific musculoskeletal or CNS symptoms, evidence of hyperparathyroidism, hematocrit, or calcium or phosphorus levels. These findings suggest that total body aluminum, as reflected in deferoxamine-stimulated serum aluminum levels, increases as a function of time undergoing dialysis.

Demonstration of aluminium in iliac bone: correlation between aluminon and solochrome azurine staining techniques with data on flameless absorption spectrophotometry

The presence of excess aluminium was investigated in 204 samples of iliac bone from 197 patients with chronic renal failure by using the aluminon and solochrome azurine staining techniques. The results were compared with values obtained by atomic absorption spectrophotometry (AAS). Overall, the staining reactions correlated with the AAS data, but the solochrome azurine stain was positive more often than was the aluminon stain (in 90.6% and 62.3%, respectively, of bone samples with greater than the control group mean +3SD (that is, in the range 17.8 to 113.4 micrograms aluminium/g Solochrome azurine staining was consistently positive in all cases, with greater than 23.1 micrograms aluminium/g bone but the corresponding aluminon stain was occasionally inexplicably negative in this range. In some samples solochrome azurine was positive in parts of old unresorbed cement lines when the aluminon stain was negative and the bone aluminium concentration was within the normal range or slightly increased. The stains, particularly solochrome azurine, have the advantage over AAS in that they indicate the location as well as the presence of excess bone aluminium.

Bone disease in pediatric patients undergoing dialysis with CAPD or CCPD

The histologic features of renal osteodystrophy and the prevalence of bone aluminum deposition in children receiving regular dialysis have not been described. Forty-four pediatric patients undergoing continuous ambulatory (CAPD) or cycling (CCPD) peritoneal dialysis had bone biopsies and deferoxamine (DFO) infusion tests; all were receiving oral calcitriol. Osteitis fibrosa (OF) was found in 39%, mild lesions (M) in 25%, normal histology (NH) in 16%, aplastic lesions (AP) in 11%, and osteomalacia (OM) in 9%. Bone surface aluminum (SA) was present by histochemical staining in 10 out of 20 given aluminum-containing phosphate-binding agents and in 0 of 24 treated with calcium carbonate; chi 2 = 15.5, P less than 0.0001. Serum biochemistries and DFO infusion tests failed to predict bone histology, but plasma aluminum levels were markedly elevated and bone aluminum content was highest in patients with OM. Bone formation rate (BFR) correlated with serum parathyroid hormone (PTH), r = 0.55, P less than 0.001; BFR was inversely related to bone aluminum content (r = -0.42, P less than 0.01), even in patients with OF (r = -0.66, P less than 0.05). All patients with SA greater than 30% had normal or reduced BFR when compared to those with SA less than 30%; chi 2 = 12.2, P less than 0.005. Based on SA greater than 30%, six patients were classified as aluminum-related bone disease: three OM, one AP, and two NH. Two-thirds of pediatric patients undergoing CAPD/CCPD have persistent hyperparathyroidism despite treatment with calcitriol, but aluminum can adversely affect BFR when SA exceeds 30% regardless of histologic lesion or serum PTH level.

Dentin in chronic renal failure: an ultrastructural study

Disturbances in the mineralization of hard tissues in patients suffering from chronic renal failure and in patients undergoing chronic hemodialysis are a well-established phenomenon. These disturbances are the result of complex pathophysiologic alterations in calcium and phosphorus metabolism. Disturbances in the dentin of teeth, analagous to those occurring in bone, were not recognized until 1983 when it was reported that a significantly thicker predentin layer was present in the teeth of patients with chronic renal failure and in patients being treated with chronic hemodialysis (1). The aim of the present study was to conduct a comparative ultrastructural (SEM) analysis of dentin in this group of patients. A wide spectrum of changes was detected, ranging from mild disturbances with increasing tubule irregularity and focal obliteration of tubule lumens, to widespread formation of dysplastic dentin exhibiting numerous mineralized, largely atubular globules with only occasional large, irregular tubules. In general, these changes appeared to reflect the type and effectiveness of treatment rendered (renal transplant or hemodialysis therapy). The findings suggest that dentin exhibits significant ultrastructural alterations when the underlying homeostatic regulation of calcium and phosphorus metabolism is disturbed in systemic disorders such as chronic renal failure.

Surgery in the patient with acute or chronic renal failure

Medical management of the surgical patient with renal dysfunction revolves primarily around the application of sound medical principles used in the care of all patients. In this article, the unique peculiarities associated with renal failure are stressed. Knowledge of these points is vital in securing a favorable outcome for the patient.

Radiographic manifestations of experimental aluminum toxicity in growing bone

To evaluate the effect of aluminum on growing bone in the presence of normal renal function, the following experiment was performed. Eight littermate pair-fed pigs (5 weeks old) were randomly assigned to one of two study groups: control C, n = 4, or aluminum treated Al, n = 4. Daily intravenous injections of either aluminum 1.5 mg/kg/day (Al group) or vehicle only (C group) were given during the 8-week duration of the study. The radiographic findings which appeared in the aluminum-treated group and not in the controls consisted of areas of sclerosis in the submetaphyseal regions and the periphery of epiphyses. In addition there was separation of the anterior tibial tubercle. The growth plates did not increase in width despite the presence of osteomalacia and histologic evidence of extensive deposition of aluminum in bone. The area of sclerosis visualized in the radiographs correlated histologically with thickened bony trabeculae. The increased width of these trabeculae is attributable to an increase in primary spongiosum and broadened seams of osteoid.

Laser microprobe mass analysis (LAMMA) to verify the aluminon staining of bone

Triammonium aurin tricarboxylate (aluminon) has been used to localize aluminum in 2 micron sections of undecalcified, methyl methacrylate embedded bone obtained from patients with terminal chronic renal failure. Aluminum appeared in four cases as bright red lines at the mineralized-bone boundary. In two cases, however, purplish lines were found and one patient showed red as well as purplish lines. Laser microprobe mass analysis (LAMMA) identified aluminum at the location of the red lines and both aluminum and iron at the purplish lines. Furthermore, both iron and aluminum were found in histiocytic bone marrow cells, which showed brownish aluminon staining. It appears that when aluminum and iron occur together, aluminon staining may yield aberrant results. This study shows that LAMMA can be used for the identification of elements sought by histochemical methods and thus permits the evaluation of their staining effects.

Removal of aluminum during hemodialysis: effect of different dialyzer membranes

Aluminum toxicity is now widely recognized as a major cause of morbidity in patients on maintenance hemodialysis. Desferrioxamine (DFO) chelation therapy has been suggested as a method of AI removal in such patients, though the most appropriate treatment schedule is yet to be established. In the present study, AI removal following DFO infusion was evaluated using two different dialyzer membranes to test the hypothesis that polyacrilonitrile (PAN) membranes permit better AI clearance. All patients studied had significantly elevated plasma AI concentrations (1.22 to 9.45 mumol/L; normal less than 0.56 mumol/L). Plasma AI did not correlate with estimated total AI intake. During hemodialysis with a cuprophane membrane, AI clearance ranged from 33.5 to 42.1 mL/min. Total AI removal was 192.2 +/- 90.4 mumol during cuprophane dialysis. During hemodialysis with a PAN membrane, AI clearance ranged from 35.7 to 54 mL/min. Total AI removal was 154.2 to 93.9 mumol during PAN dialysis. The differences in AI clearance and total AI removal were not statistically significant. It is concluded that use of a PAN membrane does not significantly enhance DFO-AI clearance.

Elevated bone aluminum content in dialysis patients without osteomalacia

In almost all dialysis patients, bone aluminum content (BAC) is elevated in comparison with levels in normal subjects. Extremely high BAC (200 micrograms or more of aluminum per gram of bone) is significantly associated with classic aluminum-related osteomalacia. We noted three patients with elevated BAC but without histologic evidence of typical osteomalacia. Two of the patients had moderately severe osteitis fibrosa (hyperparathyroidism), and one patient had mixed uremic bone disease--predominantly hyperparathyroidism but some impairment of bone mineralization as well. As has recently been reported by others, the deferoxamine infusion test yielded unusual results in these patients. On the basis of our observations, we believe that an isolated measurement of BAC to determine whether aluminum-related osteomalacia is present has certain limitations. Aluminum-related bone disease can be accurately diagnosed only with use of bone histomorphometry. Elevated levels of immunoreactive parathyroid hormone may offer protection from the toxic effects of aluminum.

Aluminum intake from non-prescription drugs and sucralfate

The use of non-prescription antacids to control hyperphosphatemia has been implicated as a primary cause of aluminum intoxications in patients with reduced renal function. Additional reports suggest that oral aluminum intake may have adverse effects on mineral metabolism of patients with normal renal function. The non-prescription drugs that contain substantial quantities of aluminum salts include some antacids, buffered aspirins, antidiarrheals, and vaginal douches. Sucralfate, an anti-ulcer drug available by prescription, is the aluminum salt of sucrose sulfate. If taken as directed, the daily aluminum intake from the antacids can be as much as 5,000 mg. When aluminum buffered aspirins are used as part of the drug therapy for rheumatoid arthritis, aluminum intake can be elevated by 700 mg/day. Although aluminum intoxications have been reported among patients with reduced renal function, existing reports are not sufficient to estimate whether the chronic elevation of aluminum intake from drugs is causing adverse health effects among other patient populations.

Aluminum intoxication from aluminum-containing phosphate binders in children with azotemia not undergoing dialysis

Aluminum intoxication developed in three infants with azotemia who were not undergoing dialysis and who had been treated with aluminum hydroxide from the first month of life. Biopsies of the iliac crest demonstrated the presence of severe osteomalacia and massive deposition of aluminum in the bone. Serum aluminum levels were significantly (P less than 0.001) higher in these 3 infants and in 1 other, all of whom received more than 100 mg of elemental aluminum per kilogram of body weight per day (mean +/- S.D., 371.0 +/- 178.9 ng per milliliter [13.75 +/- 6.6 mumol per liter] ) than they were in 8 older children with azotemia who were not undergoing dialysis and who received less than 100 mg of elemental aluminum per kilogram per day (27.0 +/- 18.6 ng per milliliter [1.0 +/- 0.68 mumol per liter] ), 7 such children who did not receive aluminum hydroxide (20.28 +/- 9.2 ng per milliliter [0.75 +/- 0.34 mumol per liter] ), and 16 children with normal renal function (21.04 +/- 4.9 ng per milliliter [0.78 +/- 0.18 mumol per liter] ). In all the children with azotemia who were treated with aluminum hydroxide, there was a positive correlation (r = 0.90; P less than 0.01) between the serum aluminum level and the daily dose of elemental aluminum. These studies indicate that gastrointestinal absorption of aluminum can lead to aluminum intoxication in children with azotemia, and that infants may be particularly susceptible to this complication of therapy.