Prevalence and risk factors associated with low bone mineral density in Asian adolescents with anorexia nervosa and atypical anorexia nervosa.

Objective: This retrospective study aimed to evaluate the prevalence and risk factors for low bone mineral density (BMD) at diagnosis in Asian adolescent females with anorexia nervosa (AN) and atypical AN.

Method: We analyzed the BMD results for 213 patients between 10 and 18 years of age, with AN and atypical AN receiving care at a pediatric hospital in Singapore. We used linear regression analyses to determine if type of eating disorder, premorbid weight, and duration of amenorrhea were risk factors for low BMD. For a subset of patients with repeat BMD evaluation, we used paired t-tests to assess the impact of weight or menstrual restoration on the change in BMD.

Results: The prevalence of BMD height-for-age Z-scores <-2 at presentation was higher in patients with AN (13.0%) than atypical AN (2.3%) (p = .034). In multivariate regression, a diagnosis of atypical AN was protective against low BMD at the lumbar spine (B = 0.394, p = .009) and total body less head (B = 0.774, p = .010). Duration of amenorrhea was not associated with BMD across all sites. For those with repeat BMD measures, there was significantly less deterioration in the BMD Z-scores for patients with weight or menstrual restoration (R = -0.22 ± 0.59, NR = -0.69 ± 0.43, p = .029).

Conclusions: Duration of amenorrhea was not associated with BMD in this sample. A diagnosis of AN was correlated with lower BMD than atypical AN. Further research is needed to better understand the relationship between amenorrhea, weight status, and bone health in Asian adolescents with eating disorders.

Public Significance: In this sample, 13% of Asian adolescents with AN and 2.3% of Asian adolescents with atypical AN have low BMD. In our study population, duration of amenorrhea was not correlated with BMD. Among adolescents with AN, a history of being underweight at the highest pre-morbid BMI, is correlated with low BMD. It is important for physicians to take a thorough weight history in evaluating bone health in this population.