Bone mass evolution after renal transplantation

Abstract

To the Editor: Now that tailoring immunosuppression is possible, efforts have concentrated on the prevention of post-transplant complications, including bone demineralization. In this context, the recent study by Westeel et al suggests that cyclosporine-steroid immunosuppression may prevent post-transplant osteopenia1Westeel F.P. Mazouz H. Ezaitouni F. Cyclosporine bone remodeling effect prevents steroid osteopenia after kidney transplantation.Kidney Int. 2000; 58: 1788-1796Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar. Unfortunately, this conclusion is not convincing. It rests only upon data collected between 3 and 24 months post-transplantation. When the first post-transplant months are included, all published studies agree that cyclosporine-steroid–based immunosuppression is consistently associated with bone loss2Julian B.A. Laskow D.A. Dubovsky J. Rapid loss of vertebral mineral density after renal transplantation.N Engl J Med. 1991; 325: 544-550Crossref PubMed Scopus (607) Google Scholar,3Almond M.K. Kwan J.T.C. Evans K. Cunningham J. Loss of regional bone mineral density in the first 12 months following renal transplantation.Nephron. 1994; 66: 52-57Crossref PubMed Scopus (191) Google Scholar. We have confirmed this conclusion in 44 unselected graft recipients Figure 1. The bone loss between 3 and 24 months post-transplantation that can be anticipated from the results of previous studies averages 1.5%2Julian B.A. Laskow D.A. Dubovsky J. Rapid loss of vertebral mineral density after renal transplantation.N Engl J Med. 1991; 325: 544-550Crossref PubMed Scopus (607) Google Scholar,3Almond M.K. Kwan J.T.C. Evans K. Cunningham J. Loss of regional bone mineral density in the first 12 months following renal transplantation.Nephron. 1994; 66: 52-57Crossref PubMed Scopus (191) Google Scholar. The results of Westeel et al that were collected during this interval are thus of borderline significance when the precision error of the methods used to evaluate bone mass is considered (0.4 and ± 2 to 4% for the dual energy x-ray absorptiometry and the quantitative computed tomography4Blake G.M. Wahner H.W. Fogelman I. Technical principles of x-ray absorptiometry.The Evaluation of Osteoporosis: Dual Energy X-ray Absorptiometry and Ultrasound in Clinical Practice. Martin Dunitz Ltd., London1999: 45-72Google Scholar, respectively). Finally, these authors' conclusions are limited by patient selection, specifically excluding osteopenic post-menopausal women. Indeed, the independent effect on bone mass when the normal ovarian cycle is resumed in pre-menopausal women, as well as the prescription of potential osteogenic drugs (such as statins or thiazides) and the increased mobilization associated with successful renal transplantation, is not considered. The clinician concerned with the fate of the patient throughout the first post-transplant year will find minimal data to rely on cyclosporine to specifically protect bone structure.