Bone loss after orthotopic liver transplantation.

PURPOSE

We assessed changes in body composition and bone loss following liver transplantation to determine if bone loss is related to the underlying liver disease or to other factors such as sex, menopause, or graft rejection episodes.

PATIENTS AND METHODS

Our cross-sectional study component compared bone mass and body composition in 31 patients at 1 year after liver transplantation versus 33 pregraft patients with chronic liver disease. Bone mass was measured by dual energy X-ray absorptiometry (DXA) using anteroposterior views of the total body to determine bone mineral content (BMC), and of the lumbar spine to assess bone mineral density (BMD). The body fat content was also determined by DXA. Radiographs of the thoracic and lumbar spine were also obtained. In our longitudinal study component, 16 patients from the pregraft group underwent bone mass assessment again 1 year after transplantation.

RESULTS

Graft patients and pregraft patients both had reduced lumbar spine BMD compared to age- and sex-matched normal values (P < 0.001). A 4.75% increase in body fat content was observed after liver transplantation (P < 0.05). In the cross sectional study, bone mass of the spine and total body were not different in pre- and posttransplantation patients. However, the longitudinal study revealed significant decreases in spinal BMD and total body BMC, with a mean 3.5% decrease and a rate of loss of 0.55% per month. In addition, a dramatically high prevalence (29%) of vertebral fractures was observed in grafted patients, contrasting with a low prevalence (8.4%) of fractures in pregraft patients. Menopause, primary biliary cirrhosis, and chronic alcohol abuse were the principal contributing factors for osteoporosis. Patients with vertebral fractures had a marked 17.4% decrease of the lumbar spine BMD (P < 0.001) and a 22% decrease in total BMC when compared to patients without fractures (P < 0.01).

CONCLUSION

Patients with orthotopic liver transplantation for chronic liver disease evaluated 1 year after transplantation have a high prevalence of vertebral fractures. Cross sectionally, bone mass was not different in patients before and after transplantation, but the longitudinal study showed that liver transplantation induced a marked and rapid bone loss. Bone loss due to transplantation could enhance the risk of new vertebral fractures, as shown by the high prevalence of vertebral fractures. These results emphasize the need to identify patients with low bone mass by bone densitometry before transplantation.