Impaired bone metabolism following augmentation cystoplasties in growing rats

Objective: The aim of this study was to evaluate the possible risk of im pa ired bone metabolism following augmentation cystoplasties with different ga strointestinal segments. Method: 60 young rats underwent augmentation cystoplasties using gastric, i leal or sigma segments, or sham operations. An additional group undergoing sigma-cystoplasty received the bisphosphonate ibandronate to inhibit osteoc last-mediated bone resorption. Bone mass in the lumbar spine and tibia was analyzed monthly by in vivo densitometry. Bone turnover was assessed monthl y using current bone metabolism markers for a period of 16 weeks. Bone ashi ng and serum analyses of the osteotropic hormones parathyroid hormone (PTH) , and 25-OH vitamin D3 were performed at study conclusion. Results: Following ileocystoplasty, reduced bone mineral density (BMD) was seen throughout the observation period; this was pronounced in the trabecul ar bone. The decline in BMD was associated with decreased serum 25-OH vitam in D3 levels. Following sigmacystoplasty, bone calcium content was signific antly decreased; this could be prevented by ibandronate. No skeletal change s occurred in the gastrocystoplasty group. Serum pH was not altered in any group, and markers of bone resorption indicated normal bone resorption rate s. Conclusion: There is a significant correlation between impaired bone metabo lism and the type of segment used for bladder augmentation. While the use o f the ileum (and probably the colon too) causes osteopenia, gastrocystoplas ties seem to have little influence on bone turnover. Copyright (C) 2000 S. Karger AG. Basel.