The association between gonadal status, body composition and bone mineral density in transfusion-dependent thalassemia

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 248-267-Osteoporosis II
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-255
Phillip Wong*1, Peter J Fuller2, Matthew T Gillespie1, Vicky Kartsogiannis1, Boyd Strauss3, Donald Bowden4 and Frances Milat1
1Prince Henry's Institute of Medical Research, Clayton VIC, Australia, 2Prince Henry's Institute, Clayton VIC, Australia, 3Monash University, Clayton VIC, Australia, 4Monash Medical Centre, Clayton VIC, Australia

Introduction: Thalassemia is a disorder of haemoglobin synthesis requiring regular transfusion therapy in its more severe form. Multiple hormonal complications, in particular hypogonadism and severe osteoporosis, can lead to changes in body composition and bone mineral density (BMD). We investigated the relationship between skeletal muscle mass, fat mass and BMD in subjects with transfusion-dependent thalassemia based on their gonadal status.

Method: A retrospective cross-sectional cohort study of 186 young adults with transfusion-dependent thalassemia at a single academic centre was analysed. Body composition and BMD (lumbar spine, femoral neck and total body) were measured using Dual energy X-ray absorptiometry (DXA) along with anthropometric measures. Intermuscular adipose free skeletal muscle mass was calculated. The association between muscle, fat and BMD was investigated through uni-, multi- and step-wise regression analyses after adjusting for multicollinearity.

Results:  43.5% were males and 56.5% were females with a median age of 36.5 and 35.4 years, respectively. Hypogonadism was reported in 44.4% of males and 44.7% of females. Skeletal muscle mass and BMD were positively correlated and were strongest in eugonadal males (0.36≤R2≤0.59) but the association was attenuated in hypogonadal males. Skeletal muscle mass (0.27≤ R2≤0.69) and total fat mass (0.26≤R2≤0.55) were positively correlated with BMD in hypogonadal females but the correlation was less pronounced in eugonadal females. Leg lean tissue mass and arm lean tissue mass in males and females, respectively, were most highly correlated to BMD in the stepwise regression analysis.

Conclusion: Skeletal muscle is positively correlated and accounts for the largest variance in BMD in males regardless of gonadal status. Fat mass and skeletal muscle mass were positively but weakly correlated to BMD in eugonadal females but the association was stronger in the hypogonadal state. Hypogonadism attenuates the strength of the muscle-bone relationship in males but strengthens the positive correlation of skeletal muscle mass and fat mass in female subjects. This study supports the notion that exercise is important for maintaining BMD and the need to optimize treatment of hypogonadism in patients with transfusion-dependent thalassemia.

Nothing to Disclose: PW, PJF, MTG, VK, BS, DB, FM

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