Aluminium toxicity in dialysis patients

Aluminium toxicity in dialysis patients is a serious medical condition that arises when aluminium accumulates in the body due to exposure during hemodialysis or peritoneal dialysis. The condition was first recognized in the 1970s and has since been significantly reduced with improved water treatment and monitoring practices.

Overview

Aluminium is a ubiquitous metal found in the environment and is used in many industrial and consumer products. Although aluminium has no known biological function in humans, its accumulation in the body can lead to toxic effects, particularly in chronic kidney disease (CKD) patients undergoing dialysis.

Patients with end-stage renal disease (ESRD) are particularly vulnerable to aluminium toxicity because their kidneys cannot effectively excrete this metal. The primary sources of aluminium exposure in dialysis patients include:

• Dialysis water containing aluminium from untreated or poorly treated municipal water supplies.
• Phosphate binders containing aluminium hydroxide.
• Contamination of dialysate.

Pathophysiology

Aluminium toxicity occurs when aluminium is absorbed into the bloodstream and deposits in various tissues, including bones, brain, and other organs. The inability of dialysis patients to excrete aluminium exacerbates its accumulation.

Effects on Bones

• Aluminium interferes with bone mineralization, leading to a condition known as osteomalacia.
• It inhibits the activity of osteoblasts and affects the metabolism of vitamin D, further contributing to renal osteodystrophy.

Effects on the Brain

• Aluminium is neurotoxic and can lead to dialysis encephalopathy, also known as dialysis dementia.
• Symptoms include speech disorders, myoclonus, seizures, and confusion.
• Chronic exposure may increase the risk of neurodegenerative diseases like Alzheimer's disease.

Other Systemic Effects

• Anemia: Aluminium interferes with erythropoiesis, leading to microcytic anemia.
• Cardiomyopathy and other cardiovascular complications have also been reported in severe cases.

Diagnosis

The diagnosis of aluminium toxicity involves clinical evaluation and laboratory tests. Key diagnostic methods include:

• Serum Aluminium Levels: Elevated serum aluminium concentrations (>60 µg/L) indicate toxicity.
• Bone Biopsy: Aluminium staining in bone biopsies confirms aluminium deposition in bone tissue.
• Neurocognitive Testing: Used to assess the effects of aluminium on the central nervous system.

Management and Prevention

Prevention and management of aluminium toxicity focus on minimizing exposure and removing accumulated aluminium.

Prevention

• Water Treatment: Advanced water purification techniques, including reverse osmosis, ensure that dialysis water is free from aluminium contamination.
• Alternative Phosphate Binders: Non-aluminium phosphate binders, such as calcium carbonate or sevelamer, are recommended for dialysis patients.
• Routine Monitoring: Regular testing of dialysis water and serum aluminium levels.

Treatment

• Chelation therapy: Administration of deferoxamine (DFO), an iron-chelating agent, binds aluminium and facilitates its removal via dialysis.
• Dialysis: High-efficiency and high-flux dialysis can enhance aluminium clearance.

Historical Context

Before the 1980s, aluminium toxicity was a common problem among dialysis patients due to inadequate water treatment and the widespread use of aluminium-based phosphate binders. The introduction of stricter standards for dialysis water and the availability of alternative phosphate binders have significantly reduced the prevalence of this condition.

See Also

• Hemodialysis
• Chronic kidney disease
• End-stage renal disease
• Phosphate binders
• Dialysis dementia
• Osteomalacia

External Links

• Kidney Disease Resources - National Kidney Foundation
• World Health Organization Guidelines for Water Quality
• Nephrology Journal - Research on Dialysis and Aluminium Toxicity