Sex-hormone-binding globulin is negatively correlated with femoral bone-mineral density in male cardiac-transplant recipients.

BACKGROUND: Osteoporosis and the subsequent increase in incidence of fractures are a common problem after cardiac transplantation.
DESIGN: We performed a cross-sectional evaluation of male cardiac-transplant recipients in a late post-transplantation period (4.2 +/- 2.6 years after cardiac transplantation, n = 21). Bone-mineral density was measured by dual-energy X-ray absorptiometry and by quantitative heel ultrasound, and the endocrine characteristics of cardiac-transplant recipients with and without vertebral fractures were investigated.
RESULTS: A significant negative correlation was observed between sex-hormone-binding globulin and femoral-neck bone-mineral density (rs = -0.699; p value = 0.001). Linear regression analysis controlling for age and body-mass index proved sex-hormone-binding globulin to be an independent negative predictor for femoral-neck bone-mineral density (r = -0.474; p value = 0.035). Patients with vertebral fractures had significantly lower femoral-neck bone-mineral density (pvalue = 0.035). However, sex-hormone-binding globulin, total and free testosterone, and estradiol did not exhibit significant associations with vertebral fractures in our patients.
CONCLUSION: This investigation demonstrates for the first time an association between high sex-hormone-binding globulin levels and low femoral-neck bone-mineral density in a cohort of male cardiac-transplant recipients. Our data support the important role of sex-hormone-binding globulin in the pathogenesis of post-transplantation bone disease, although--possibly because of the small number of patients--we could not prove an interrelation of sex-hormone-binding globulin with vertebral fractures.