Effect of aluminum on markers of bone formation resorption in chronic hemodialysis patients

Background: The prevalence of aluminum (Al)-related toxicity in hemodialysis (HD) patients has declined. However, some HD patients continue to receive Al-based phosphate binders, in part because of the expense of Al-free binders. Objective: To explore the effect of Al-based binders and their discontinuation on iron status, and markers of bone formation resorption in HD patients. Methods: Following an initial screen of serum Al levels in 37 HD patients, a second screening was performed after discontinuation of Al-based binders in a 2-year follow-up. A desferrioxamine (DFO; 5 mg/kg) test, and assessment of iron status and bone markers were conducted in the second screening. Results: Mean serum Al level was initially 27.8 +/- 10.3 mu g/L. Thirteen patients had a serum Al >30 mu g/L, a level considered possibly toxic. There was a positive correlation between serum Al levels, HD duration, and cumulative dose of Al-based binder. At the second screening, the mean serum Al level decreased to 12.5 +/- 7.4 mu g/L. The mean serum Al level increased to 26.0 +/- 14.7 mu g/L post-DFO, but in none of the patients did the change in serum Al exceed the 50 mu g/L threshold associated with Al-induced bone disease. The decrease in serum Al level was associated with a significant increase in intact parathyroid hormone (iPTH) whereas total alkaline phosphatase did not change. Conclusions: We recommend that if Al-based phosphate binders are used in HD patients, serum Al level, iron, and markers of bone formation resorption be closely monitored to ensure safe use of these drugs.