Abstract
Low bone mineral density (BMD) is a frequent complication in anorexia nervosa (AN). There are controversial points of views regarding the restoration of bone mineralization after recovery in AN. We aimed to assess changes of BMD at 3 years in patients with AN and to explore the relationships between body composition, physical activity, and BMD. Patients with AN were included from 2009 to 2011 in a first visit (T0) with evaluation of weight, height, body mass index (BMI), body composition [fat mass (FM) and fat-free mass], and BMD. Those who had low BMD, either osteoporosis or osteopenia, were admitted in a second visit (T1) to carry out a new bone densitometry examination and body composition; they were also asked for their physical activity. At T0, our study involved 160 patients. Low BMD was observed in 53.6% of them and significant factors associated with demineralization were lower BMIs (16.5 ± 2.1 vs 17.3 ± 2.3 kg/m2, p = 0.01) and higher duration of AN (11.4 ± 10.5 vs 6.4 ± 6.5 years, p = 0.001). At 3 years follow-up (T1), 42 patients were involved and no significant changes in BMD were observed despite body weight increase (3.8 ± 6.1 kg). Interestingly, FM gain was a significant factor associated with BMD improvement at follow-up (8.0 ± 9.1 vs 3.0 ± 3.5 kg, p = 0.02). Our findings suggest that the restoration of normal bone values is not related to the increase of body weight, at least after 3 years. FM seems to play an important role in the pathophysiological mechanism of osteoporosis and osteopenia in AN.
Highlights
Anorexia nervosa (AN) is characterized by a difficulty to maintain minimal weight, a fear of gaining weight, a disturbed body image, often associated with denial based on criteria from the Diagnostic and Statistical Manual of Mental Disorders [1]
In a first visit (T0), every patient has been evaluated for weight, height, body mass index (BMI), body composition [fat mass (FM) and fat-free mass (FFM)], and bone mineral density (BMD)
The results of BMD were expressed as T-scores and we considered that patients with −2.5 ≤ T-score < −1 had osteopenia and patients with T-score < −2.5 had osteoporosis
Summary
Anorexia nervosa (AN) is characterized by a difficulty to maintain minimal weight, a fear of gaining weight, a disturbed body image, often associated with denial based on criteria from the Diagnostic and Statistical Manual of Mental Disorders [1]. AN is associated with multiple and severe somatic complications related to malnutrition including bradycardia, hypotension, anemia, and hormonal imbalance [4]. Conventional bed rest imposed to patients with AN is probably detrimental on BMD, since immobilization is a well-established risk factor for bone loss [10]. The benefit of bisphosphonates for the treatment of BMD during AN is not established [14], Miller et al have previously reported a significant increase in BMD in adult women with AN with risedronate compared with placebo in a 1-year follow-up study [15]. Other studies have reported a decrease in bone turn-over with bisphosphonates, in adolescent patients with AN [16]
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