Evaluation of bone mineral density after renal transplantation under a tacrolimus-based immunosuppression: a pilot study.

BACKGROUND: Progressive bone loss consistently complicates renal transplantation (TP) in patients given an immunosuppression including prednisolone. The adjunction of cyclosporine in the immunosuppressive regimen does not reverse the negative impact of renal TP on the skeleton. The post-transplant effect of tacrolimus on bone mass is still unknown. METHODS: We evaluated the evolution of bone mineral density (BMD) and various biochemical markers over the first 12 months following renal TP in 23 patients given an immunosuppression combining tacrolimus and low-dose prednisolone. BMD of lumbar spine, total hip and hip subregions was measured by dual-energy X-ray absorptiometry within the first 15 days and 1 year after TP. RESULTS: At the time of TP, the average BMD was low in both the lumbar spine and the hip. After TP, a normalization of serum creatinine and a decrease in serum phosphate and iPTH levels occurs. Serum alkaline phosphatase level significantly rose transiently within the first 6 months and decreased thereafter. At 1 year post TP, BMD remained unchanged in the lumbar and in the trochanter subregions and rose in the other sites. BMD increased by at least 2% in 8, 13, 10 and 10 out of the 23 patients in the lumbar, neck, trochanter and total hip subregions, respectively. No correlation was found between evolution in BMD and age, sex, dialysis duration, level of hyperparathyroidism, prednisolone and tacrolimus cumulative intake and prescription of calcium, vitamin D or hormone replacement therapy. CONCLUSIONS: An immunosuppression combining tacrolimus and low-dose prednisolone might avoid the usual post-TP bone loss. Further randomized double-blind studies evaluating a larger cohort of patients should be undertaken to compare the effect of cyclosporine and tacrolimus on bone mass.