Dialysis encephalopathy in a non-dialysed uraemic boy treated with aluminium hydroxide orally

Intestinal absorption of aluminium in rats

To study the mechanism of intestinal aluminium (Al) absorption, an experimental investigation into the uptake of Al from the rat gut was undertaken. The small intestine was perfused in situ for 60 min with isotonic media containing 4.63, 9.25, and 18.50 mmol/l Al chloride at pH 4.0 and 7.0. Portal and systemic blood were sampled and analysed for its Al content by flameless atomic absorption spectrophotometry. It was found that the intestinal absorption of Al in rats is concentration and pH dependent.

Role of aluminum hydroxide in raising serum aluminum levels in children undergoing continuous ambulatory peritoneal dialysis

Serum aluminum concentrations were measured in 16 children undergoing continuous ambulatory peritoneal dialysis after 7.9 +/- 2.1 (mean +/- SE) and 16.6 +/- 2.3 months of therapy, when the estimated simultaneous oral Al intake from Al hydroxide gels was 98 +/- 20 and 104 +/- 32 mg/kg/day, respectively. Serum Al concentrations were 55.2 +/- 11.4 and 59.8 +/- 10.4 micrograms/L, respectively, compared to 8.2 +/- 1.1 micrograms/L in normal children (P less than 0.001). Serum Al levels correlated with oral Al intake (r = 0.86, P less than 0.001) and inversely with body weight (r = -0.68, P less than 0.01) and age (r = -0.67, P less than 0.01). The youngest patient with the highest serum Al concentrations (208 and 174 micrograms/L) and greatest Al intake (310 and 192 mg/kg/day) had bone biopsy features characteristic of aluminum-related bone disease. Thus, higher aluminum intake per kilogram body weight given to young children is likely to raise the serum Al levels and increase the risk of osteomalacia. Aluminum-containing antacids should be used with caution in infants and young children with renal failure.

A method of studying the intestinal absorption of aluminium in the rat

Aluminium (Al) intoxication in dialysis patients is held to be caused not only by Al in the dialysis fluid but also by Al from orally administered phosphate binders. Studies on Al absorption in patients and healthy individuals as well as in animals are still scarce, and do not provide sufficient data to characterize the absorption process. This paper presents a method of studying the process of Al absorption in a perfusion system of rat small intestine in vivo, in combination with a cannulation system of the portal vein for serial blood sampling. Determination of concentrations of an absorbed substance in samples of both the perfusion medium and the portal blood, collected during the perfusion medium and the portal blood, collected during the perfusion period, may clarify the nature of the absorption process. Although this method appears to be useful for the study of the intestinal absorption of any substance, it was adapted for the study of the intestinal absorption of Al compounds. The usefulness of this method for studying Al absorption was demonstrated in an experiment in which Al chloride (0.5 g/l) in buffered media of pH 7.0, 7.5, and 8.0 was perfused through the rat small intestine over a period of at least 30 min. The results of this experiment indicate that a decrease in pH of the perfusion medium leads to an increase in absorption of Al in the portal blood.

Aluminum loading in children with chronic renal failure

Plasma aluminum levels were measured in 17 children with chronic renal failure who were receiving aluminum containing antacids for the control of hyperphosphatemia. Seven children were on hemodialysis, five on peritoneal dialysis, and five were awaiting dialysis with creatinine clearances between 10 to 20 cc/min/1.73 m2. Plasma aluminum levels correlated directly with oral aluminum dosage; extremely high levels were documented in small, nondialyzed children. Bone aluminum levels were measured in four children with high plasma levels and confirmed significant aluminum loading. Other factors such as the level of aluminum in dialysate and tap water were measured and were not contributory. All patients with plasma aluminum levels greater than 100 micrograms/liter had signs of aluminum toxicity and were receiving greater than 75 mg/kg/day of elemental aluminum orally. We concluded that children who require greater than 30 mg/kg/day of elemental aluminum to control hyperphosphatemia should have plasma aluminum levels monitored and/or be considered for other forms of therapy including more restricted diets and earlier or more aggressive dialysis.

Aluminium concentrations in the brain and bone of rats fed citric acid, aluminium citrate or aluminium hydroxide

Male Sprague-Dawley rats were treated daily by gastric intubation (6 days/wk) with 100 mg aluminium/kg body weight in the form of aluminium hydroxide (9 wk) or aluminium citrate (4 wk), with citric acid (4 wk) or with tap-water (control, 9 wk). Young adult and aged Wistar rats were treated with 100 mg aluminium/kg body weight as aluminium hydroxide or with carboxymethylcellulose (vehicle controls). The cerebral cortex, hippocampus, cerebellum and samples of bone from each rat were analysed for aluminium, after digestion with nitric acid, using graphite furnace atomic absorption spectroscopy. The mean aluminium concentrations detected in the control Sprague-Dawley rats were 0.013-0.022 microgram/g wet weight in the various brain regions and 0.355 microgram/g in the bone. No significant increase in tissue aluminium concentrations was observed in Sprague-Dawley or Wistar rats after treatment with aluminium hydroxide. However the rats treated with aluminium citrate showed significantly increased concentrations of aluminium in all the brain regions studied (0.057-0.121 microgram A1/g) and in the bone (12.9 micrograms A1/g). Elevated aluminium concentrations in the cerebral cortex and bone were also observed in the animals fed citric acid suggesting possible absorption of the citrate chelate presumably formed with the traces of aluminium present in the diet.

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.

The health effects of aluminum compounds in mammals

This review, which is based on evaluation of information published in the last decade related to the health effects of aluminum compounds in mammals, directs attention to the well-documented effects of A1(III) compounds on phosphate metabolism. It is suggested that the toxic effects currently associated with A1(III) compounds are dependent upon the nature of A1(III) complexes formed from electron donating groups, rather than restricted to the presence of the high charge density matrix of A1(III) itself.

Pattern-reversal visual evoked potentials in patients with chronic renal insufficiency

Visual evoked potentials (VEPs) were recorded from 88 patients with chronic renal insufficiency twice at a 6 month interval. In dialysed patients statistically significant decreases in amplitudes and prolongations of VEP peak latencies were found. Azotaemic non-dialysed patients showed related, but smaller, changes in their VEPs. In patients after kidney transplantation the VEP amplitudes were normal but peak latencies were prolonged. No systematic significant relationship between the VEPs and creatinine and urea levels in the blood could be shown.

The prophylactic reduction of aluminium intake

The use of modern analytical methods has demonstrated that aluminium salts can be absorbed from the gut and concentrated in various human tissues, including bone, the parathyroids and brain. The neurotoxicity of aluminium has been extensively characterized in rabbits and cats, and high concentrations of aluminium have been detected in the brain tissue of patients with Alzheimer's disease. Various reports have suggested that high aluminium intakes may be harmful to some patients with bone disease or renal impairment. Fatal aluminium-induced neuropathies have been reported in patients on renal dialysis. Since there are no demonstrable consequences of aluminium deprivation, the prophylactic reduction of aluminium intake by many patients would appear prudent. In this report, the major sources of aluminium in foods and non-prescription drugs are summarized and alternative products are described. The most common foods that contain substantial amounts of aluminium-containing additives include some processed cheeses, baking powders, cake mixes, frozen doughs, pancake mixes, self-raising flours and pickled vegetables. The aluminium-containing non-prescription drugs include some antacids, buffered aspirins, antidiarrhoeal products, douches and haemorrhoidal medications. The advisability of recommending a low aluminium diet for geriatric patients is discussed in detail.

The prevalence of bone aluminum deposition in renal osteodystrophy and its relation to the response to calcitriol therapy

A histochemical stain for bone aluminum allowed us to determine the prevalence and staining characteristics of aluminum in renal osteodystrophy. The staining method correlated well with the results of atomic-absorption studies in 96 samples (r = 0.81; P less than 0.001). We examined 315 bone-biopsy samples. No aluminum was seen in controls or patients with nonrenal bone disease. In renal osteodystrophy, the mean level of stainable aluminum was significantly higher in osteomalacic lesions (1.12 +/- 0.09 mm per square millimeter of tissue area) than in mild, mixed, of fibrotic lesions (0.43 +/- 0.06, 0.34 +/- 0.11, and 0.10 +/- 0.03 mm per square millimeter, respectively; P less than 0.001). Seventy per cent of osteomalacic samples had heavy aluminum staining. The bone-apposition rate, measured by double tetracycline labels, was low in 89 per cent of the samples with high levels of aluminum. The mean level of stainable bone aluminum in patients who had a clinical response to calcitriol was significantly lower than in those who did not respond (0.13 +/- 0.4 vs. 1.06 +/- 0.9 mm per square millimeter; P less than 0.01). We conclude that aluminum deposition is associated with impaired bone formation or mineralization and with a poor response to calcitriol therapy.

Progressive encephalopathy in children with chronic renal insufficiency in infancy

A retrospective analysis of children with renal failure during the first year of life revealed that 20 of 23 patients developed profound neurologic abnormalities. The encephalopathy was characterized by developmental delay, microcephaly, hypotonia, seizures, dyskinesia, and EEG abnormalities. No patient had been dialyzed, and four had not received aluminum salts prior to the development of neurologic symptoms. Inadequate statural growth and poor nutrition were present in all patients. It is probable that infants with chronic renal insufficiency are more susceptible to the development of this syndrome than are older children or adults because of the significant growth and maturation of the brain that occurs during the first years of life.