Bone Abstracts

Objectives: Anorexia nervosa (AN) is condition of severe low body weight as a result of impaired body image and a fear of gaining weight, often occurring during adolescence, a critical time for bone development. AN has been associated with low bone mass and impaired bone strength. However, many studies have failed to consider body composition, particularly lean mass when assessing bone health. The purpose of this study was to assess if females with AN have an appropriate amount of muscle and bone for their height.

Methods: Twenty adolescent females aged 13–19 with AN were compared with age and height matched controls from the Pediatric Bone Mineral Accrual Study. DXA scans were obtained for total body lean mass and bone mineral content (BMC), as well as hip and spine BMC. Bone variables were compared between groups using independent sample t-tests. Z-scores were calculated adjusting for the participant’s race, sex, height, weight, actual BMC and predicted BMC using published international pediatric reference standards. Hip structural analysis (HSA) was also applied to all hip scans.

Results: By design there was no significant difference in age and height between groups. Females with AN had a lower body weight (52.3 vs 65.5 kg) and lower body fat (23 vs 33%) (P<0.05), but no difference in lean mass. Females with AN were found to have significantly lower total body bone area (1861 vs 1984 cm²); however, had significantly greater total body aBMD (1.07 vs 1.00 g/cm²) and lumbar spine area (59.1 vs 51.2 cm²) (P<0.05). AN females had normal BMC z-scores for total body, total hip and lumbar spine (+0.77, −0.20, +0.32, respectively). HSA analysis revealed a reduced aBMD, increased cross-sectional area, and increased sectional modulus in AN females (P<0.05).

Conclusions: We found, on average, females with AN had an adequate amount of bone for their size. In this group there was no difference in lean mass between controls and females with AN. Thus, it may be that a higher lean mass is associated with preserved bone health parameters in this population despite a low body weight and fat mass.

Disclosure: The authors declared no competing interests.