Stainable aluminum and not aluminum content reflects bone histology in dialyzed patients

Quantitative evaluation of stainable bone aluminum and measurement of bone aluminum content were done in 55 patients on chronic maintenance dialysis. All patients underwent bone biopsies. Histomorphometry of static and dynamic parameters of bone structure, bone formation and resorption, and quantitation of stainable bone aluminum at the osteoid-bone interface were performed. In addition, bone aluminum content was measured by atomic absorption spectrophotometry. Bone aluminum content was elevated in all patients (81±9.6 vs. 18±6 μg/g dry wt) and stainable aluminum was found in 47% of them. All patients with predominant low-turnover osteomalacia or adynamic bone disease displayed stainable bone aluminum. In contrast, stainable bone aluminum was not present in individuals with predominant-hyperparathyroid bone disease. Patients with stainable aluminum had lower bone mass (P<0.05), higher volume and surface of lamellar osteoid (P<0.01), less volume and surface of woven osteoid (P<0.05 and P<0.01), lower osteoblastic and osteoclastic indices (P<0.01), less doubly labelled osteoid seams, lower mineral apposition rate and lower bone formation rates (P<0.05 to P<0.01). Stainable aluminum correlated with volume of lamellar osteoid and cellular parameters of bone formation and resorption, mineral apposition rate, and bone formation rates (P<0.05 to P<0.001). In contrast, bone aluminum content correlated with volume of lamellar osteoid only (P<0.001). These findings indicate that stainable aluminum at the mineralization front and not aluminum content of bone reflects the histopathologic changes found in bone of dialyzed patients.