Abstract
INTRODUCTION: Low levels of sex hormones are common in patients with chronic kidney disease (CKD) and may be a contributing factor to bone fragility. We investigated associations between levels of sex hormones and bone mineral density (BMD) in adult kidney transplantation candidates. METHODS: Volumetric BMD of spine and hip were measured by computed tomography. Parathyroid hormone (PTH), testosterone (T), estradiol (E), and sex hormone-binding globulin were measured from fasting morning blood samples. Bioavailable (Bio) T and E were calculated based on constants for protein binding. RESULTS: A total of 146 patients (102 men and 44 women) were included in the analyses. The median age was 54 years (range, 32-72 years); 32% were diabetic; and 36% received maintenance dialysis therapy. In men, Bio T was positively associated with BMD at the lumbar spine (β = 5.02, P = 0.002), total hip (β = 6.35, P = 0.001), and femoral neck (β = 13.9, P = 0.002), independently of age, body mass index, dialysis, diabetes type 1 and 2, parathyroid hormone, and steroid exposure. Bio E was positively associated with BMD at the lumbar spine (β = 0.23, P = 0.03) and femoral neck (β = 0.61, P = 0.04) using the same fully adjusted model. In postmenopausal women, Bio T was positively correlated with lumbar spine BMD (r = 0.46, P = 0.02). CONCLUSION: High endogenous levels of sex hormones are associated with greater BMD in male kidney transplantation candidates. Disturbances in the gonadal axis may contribute to skeletal fragility in men with late-stage CKD.