Risk of adynamic bone disease in dialyzed patients

Renal osteodystrophy presents with a spectrum of histologic abnormalities. A new entity characterized by a marked decrease in bone turnover without osteoid accumulation, that is, adynamic bone disease, has recently emerged. This new form was thought to be primarily related to aluminum accumulation. Since aluminum-containing phosphate binders have been widely replaced by calcium salts, adynamic bone disease would be expected to disappear over time. However, not only is adynamic bone disease observed in the absence of aluminum intoxication, its incidence does not seem to have decreased. We conducted a retrospective study in 1,803 patients on chronic maintenance dialysis who were biopsied during the last 10 years and assessed the incidence of adynamic bone disease over time in an effort to elucidate the factors associated with its occurrence. Adynamic bone disease was first seen in 1984 in the laboratory. Its incidence increased gradually over the years and, in 1991, still affected approximately 20% of the patients. The primary factors associated with the occurrence of adynamic bone disease include: (a) aluminum accumulation which is currently found in 60% of the patients on chronic maintenance dialysis undergoing biopsies, (b) increasing age of the patients on dialysis, (c) diabetes, and, possibly, (d) chronic ambulatory peritoneal dialysis. The clinical relevance of adynamic bone disease deserves further study. At present, this entity is associated with a tendency towards hypercalcemia, aging of bone due to stunted bone remodeling, a condition which might be associated with impaired repair of physiologic microdamages, and accumulation of microfractures leading to mechanical incompetence and ultimately to higher risk of fractures.