Diagnosis and management of bone disorders in chronic renal failure and dialyzed patients.

Renal osteodystrophy is multifactorial. Decreased calcium absorption from the GI tract, secondary to low calcitriol levels; hyperphosphatemia; skeletal resistance to the action of parathormone; and aluminum deposition on the surface of the bones are its main pathogenetic mechanisms. Its biochemical features include abnormalities in serum calcium, phosphate, alkaline phosphatase, parathormone, calcitriol, and aluminum concentration. Radiographic methods are of little use in the characterization of the type of osteodystrophy present, but they may be of help in assessing mineral loss from the skeleton. Clinical manifestations are from bones (pain, deformities, fractures) or from metastatic calcifications. Bone biopsy is the definitive means of diagnosis. The main histologic types of osteodystrophy include osteitis fibrosa, osteomalacia, mixed form (with features of both osteitis fibrosa and osteomalacia), and aluminum osteodystrophy (presenting as either osteomalacia or aplastic lesion). The management of renal osteodystrophy should address all the pathogenetic mechanisms. Correction of the abnormalities in calcium and phosphate metabolism and prevention of aluminum osteodystrophy are the cardinal rules of management. Specific measures (parathyroidectomy, chelation of aluminum) have clear-cut indications and usually require a bone biopsy.