How does osteomalacia present? What role does aluminum play in this type of renal osteodystrophy?
In renal failure or hemodialysis, dietary aluminum is not adequately cleared and deposits in the osteoid lamellae of newly formed bone, inhibiting mineralization, which leads to osteomalacia. Therefore in patients with ESRD, osteomalacia may be related to aluminum toxicity although it can occur without aluminum toxicity. Therefore, other common causes of osteomalacia, such as vitamin D deficiency, need to be considered, although this is now uncommon with the routine supplementation of vitamin D in patients on dialysis. Chronic hypophosphatemia and metabolic acidosis can also cause osteomalacia in some patients.
Clinically, aluminum-induced osteomalacia presents as diffuse bone pain and predisposes to insufficiency fractures. Aluminum levels, PTH, and bone-specific alkaline phosphatase (BSAP) levels are increased. Radiographic findings are osteopenia and Looser’s zones. Bone biopsy with aluminum staining is diagnostic and should be done for confirmation. Other manifestations of aluminum toxicity include an acute or chronic encephalopathy. Deferoxamine chelation therapy may be beneficial. This type of renal bone disease is becoming less common because aluminum-containing phosphate binders and antacids (including sucralfate) are now avoided and aluminum levels are monitored in patients on dialysis.
