Aims: To investigate the evolution of renal osteodystrophy in patients on maintenance dialysis, treated with lanthanum carbonate (LC) vs. standard phosphate-binder therapy (Stx).
Materials and methods: This was a 2-year, randomized, prospective, open-label study during which patients on dialysis received LC titrated to a maximum of 3,000 mg/day or their previous phosphate binder treatment with the aim to achieve target phosphorus levels of < or = 5.9 mg/dl. Paired bone biopsy samples for histomorphometric analysis were available at baseline and 1 year (LC 32, Stx 33), and at baseline and 2 years (LC 32, Stx 24).
Results: With similar phosphorus control, Stx was associated with numerically higher serum calcium levels at most visits. Results of osteocalcin and bone-specific alkaline phosphatase in LC patients were higher throughout the study and correlated with parameters of bone formation; however, the differences were not significant. Histological changes in bone turnover and volume were analyzed with respect to normal ranges. There was an improvement in bone turnover in the LC group, which was significant in the 1-year group, and an improvement in bone volume which was significant in the 2-year group. No significant changes in bone turnover or bone volume were observed in the Stx groups. In the 2-year LC group, 1 patient had osteomalacia at baseline and end of therapy, and a mineralization defect developed in 2 other patients. Several possible factors for a mineralization defect were present in these patients, but no single cause could be clearly identified. Histomorphometric parameters of bone, including formation and mineralization, did not correlate with bone lanthanum. No mineralization defect was observed in the Stx groups.
Conclusion: These findings show that similar phosphorus control with Stx and LC results in higher bone turnover after 1 year and higher bone volume after 2 years with LC.