Endocrine Abstracts

Background: There is growing awareness of skeletal impairment in individuals with Klinefelter syndrome (KS), involving both quantitative and qualitative alteration of the bone as well as an increased prevalence of vertebral fractures (VFs). Beyond hypogonadism, considerable evidence suggests that other factors may be responsible for the skeletal fragility observed in these patients. Abnormal body composition is a common finding in KS subjects, characterized by an unfavourable muscle/fat ratio with an increase in total and abdominal fat mass, but evidence of its relationship with bone health is scant.

Purpose: Based on the emerging evidence of a close relationship between bone and soft tissues with possible detrimental effect of body fat distribution on bone metabolism, we aimed at assessing the impact of body composition parameters on bone health in terms of bone mineral density (BMD), microarchitecture, and radiological VFs in adult subjects with KS.

Methods: Seventy-three adult males with KS were consecutively enrolled by two Endocrinology and Andrology Units (IRCCS Humanitas Research Hospital in Milan and ASST Spedali Civili in Brescia). Whole body dual-energy X-Ray Absorptiometry (DXA) was performed to assess lumbar spine, femoral neck and total hip BMD, trabecular Bone Score (TBS) and body composition. Prevalence of VFs was assessed by quantitative morphometry on lateral spine X-rays.

Results: Low BMD was observed in 16 patients (23%). No significant differences were found in body mass index (BMI) and several body composition parameters between KS subjects with normal and low BMD. Degraded TBS was found in 16 patients (26%) with a prevalence which resulted significantly higher in individuals with higher BMI (P=0.001), fat body mass (FBM) (P<0.001), visceral adipose tissue (VAT) (P<0.001) and/or fat mass index (P<0.001). VFs were detected in 14 patients (19%), without significant associations with BMD (P=0.983) and TBS (P=0.371). However, subjects with VFs had significantly higher percentage of truncal/leg fat ratio (P=0.011) as compared to those without VFs.

Conclusion: This study provides a first evidence that abdominal adiposity might be a determinant of VFs in KS patients, consistent with the working hypothesis that alterations in body composition could negatively affect bone health in this clinical setting. The value of TBS in predicting fractures in KS without possible interference of body composition remains to be clarified in future longitudinal studies.