CHANGES IN BONE-MINERAL DENSITY IN PATIENTS WITH PAGETS-DISEASE TREATED WITH RISEDRONATE

Objectives-To study changes in bone mineral density (BMD) in patients with Paget's disease of bone treated with risedronate. Methods-Whole b ody dual energy x ray absorptiometry (DXA) scans were carried out on 2 0 patients with Paget's disease treated with oral risedronate. DXA sca nning was carried out at baseline and 11 months. Whole body bone miner al content (BMC) was measured. In addition, regions of interest were d rawn around the skull, individual lumbar vertebrae, hemi-pelvis, femor a, and tibiae to obtain BMD for these sites. An uncoupling index was a lso calculated as the area under the curve for serum alkaline phosphat ase (ALP) divided by the area under the curve for hydroxyproline excre tion (HYPRO) for the period of treatment. Results-Median whole body BM C increased from 3057 g to 3156 g (p < 0.001) resulting from an increa se in pagetic and non-pagetic BMD. From the analysis of regions of int erest it was found that pagetic trabecular bone showed the largest inc rease in BMD. The pretreatment HYPRO and the uncoupling index were sig nificantly related to the change in EMD for all pagetic sites for a pa tient (r = 0.65, p < 0.01 and r = 0.57, p < 0.05 respectively). Conclu sion-Bisphosphonate treatment of Paget's disease results in an increas e in EMD of pagetic bone without redistribution of mineral from non-pa getic bone. The remodelling space and extent of uncoupling are signifi cantly related to increases in BMD at pagetic sites.