Aluminum and renal osteodystrophy

Bone disease is recognized as a major problem in dialysis patients. initially, hyperparathyroidism was thought to be the major cause of bone disease in these patients. However, an aluminum-related bone disease has been identified in dialysis patients receiving exogenous aluminum. Patients with hyperparathyroidism and aluminum toxicity present with similar clinical and laboratory features; therefore, diagnosis of these two bone abnormalities is often difficult. Understanding normal bone development helps to elucidate the distinctions between aluminum and renal osteodystrophy. Patients with either bone syndrome may present with hypercalcemia, elevations in parathyroid hormone levels, bone pain, fractures, and radiographic evidence of subperiosteal resorption. The subtleties of these syndromes must be understood to avoid misdiagnosis. A diagnosis of hyperparathyroidism may lead to a parathyroidectomy, exacerbating the development of aluminum toxicity. Hyperparathyroidism is associated with increased surface osteoid, a high bone formation rate, increased numbers of bone cells, abnormal "twoven" osteoid, and low serum aluminum levels. Aluminum toxicity is associated with a low rate of bone turnover, paucity of bone cells, maintenance of a "laminar" osteoid, and significant aluminum bone deposition. Serum aluminum level measurements are key to the diagnosis of aluminum toxicity. For patients displaying intermediate aluminum values, the deferoxamine (DFO) challenge test is necessary for diagnosis. If noninvasive methods fail to determine a definitive diagnosis, a bone biopsy is required.