Aluminum-related osteomalacia in renal-failure patients

Abstract

The pathophysiology, clinical presentation, prevention, and treatment of aluminum-related osteomalacia in renal-failure patients are reviewed. Aluminum-related osteomalacia can develop in patients exposed to high concentrations of aluminum either in dialysis solutions or through gastrointestinal aluminum absorption from aluminum-containing antacids used to treat hyperphosphatemia. Although the exact etiology of aluminum-related osteomalacia is unknown, aluminum is believed to inhibit bone mineralization by forming an inhibitory complex with citric acid at physiologic concentrations. The complex is deposited along bone mineralization fronts and in bone marrow. The major symptoms of aluminum-related osteomalacia include skeletal pain, fractures, and vertebral collapse. The disease is difficult to diagnose because patients may have normal or slightly elevated serum concentrations of calcium, phosphate, alkaline phosphatase, and parathyroid hormone. Direct measurement of bone aluminum content (using biopsy) is often needed to confirm diagnosis. The aluminum-chelating agent deferoxamine mesylate can be used to measure bone aluminum content indirectly. Aluminum intoxication can be managed either by preventing exposure to aluminum or by removing deposited aluminum from bone. New standards restrict aluminum content in dialysis solutions, and prevention now focuses on the use of aluminum-free phosphate binders for treatment of hyperphosphatemia. Calcium carbonate may be as effective as aluminum-containing antacids in controlling serum phosphate concentrations, but it should be used cautiously in patients who are hypercalcemic or at risk of developing metastatic calcification. Chelation therapy with deferoxamine has improved the symptoms and bone histology in a small number of patients. Clinical improvements have been seen in patients receiving intravenous deferoxamine 2-6 g per week for 20 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)