/Ciclosporin and Calcium Metabolism in Renal Transplanted Patients

The impact of ciclosporin on bone mineral metabo lism in renal transplanted patients is still debated. High serum levels of bone alkaline phosphatases and osteocal cin in ciclosporin-treated renal transplanted patients are reported by several authors, but the clinical meaning of this finding is controversial [1-3]. Some authors suggest that the rise of alkaline phosphatases and osteocalcin in ciclosporin-treated patients reflects an increase of both osteoblast activity and bone formation rate. Therefore, ciclosporin should exert a beneficial effect on bone min eralization [3] and/or a potential protection against the corticoid-induced osteoporosis [4], On the other hand, histomorphometric findings in man [5] and in rat [6] argue against the ‘increased repair hypothesis’, demonstrating a delayed healing of bone lesions in ciclosporin as com pared to azathioprine-treated renal transplanted pa tients. We studied 26 transplanted patients, 14 treated with ciclosporin and prednisolone (CS) and 12 treated with azathioprine and prednisolone (Aza). These two groups were homogeneous regarding age, sex, duration of trans plantation, plasma creatinine, and maintenance daily dose of prednisolone. Significantly higherserum alkaline phosphatase levels were observed in CS patients (230±55 vs. 160± 24 U /l; p<0.005). A sodium (150 mEq/day)and calcium (500 mg/day)-restricted diet was then given to all patients for 10 days. A reduced calcemic and calciuric response in the 4 h following an oral cal cium load (1 g) was observed in CS vs. Aza group [7]. These findings suggested the prevalence of a reduced intestinal calcium absorption and/or a high turnover osteopathy with ‘hungry bone condition' in the CS group. Fig. 1. Mean plasma activities (±SD) of ",7Ca at I and 2 h. expressed as percent of administered dose in 6 CS-treated renal transplanted patients (■. I h 30±2%, 2 h 27±3%), compared to 6 Aza-treated renal transplanted patients ( • , I h 29± 7%, 2 h 27± 4%) (p = NS).