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Long-term Effects of Anorexia Nervosa on Bone Health

Changes were traced after 5 and 10 years of recovery.

Interference with bone development and attaining peak bone mass and peak bone strength can have dramatic effects on development of osteoporosis and fracture risk later in life. Development of effective treatment has proven to be highly difficult, and we still know too little about the long-term course of bone health among those who once had AN.

Interference with bone development and attaining peak bone mass and peak bone strength can have dramatic effects on development of osteoporosis and fracture risk later in life. Results of a longitudinal study that followed 41 teenage girls with AN for 5 and 10 years after recovery has shown persistent negative effects on bone health (J Adolesc Health. 2019; 64:305).

A team of Australian researchers led by Jessica Mumford, MBBS followed the participants for 5  (28 girls) or 10 years (13 girls) using dual-energy x-ray absorptiometry (DXA) of the total body, lumbar spine, and proximal femur, and with peripheral quantitative computed tomography (pQCT) at the radius and tibia, along with serum biochemistry, physical measurements (height, weight, and body mass index), and  patient questionnaires, including the Eating Disorder Examination Questionnaire and a customized questionnaire to assess menstrual, fracture, and exercise history. pQCT is a radiographic scanning modality that enables discrete analysis of the cortical and trabecular bone compartments

DXA body composition was done using retrospective data (obtained at the initial diagnosis of AN), and from the 5- and 10-year follow-up data. Baseline mean age was 14.6 years, mean body mass index, or BMI (kg/m2) was 16.6, and mean Fat % was15.9%. At the follow-up appointments, mean BMI was 21.2 and Fat% was 30.5%. At baseline, the entire cohort’s body weight, BMI, Fat%, were lower than those of controls. While there was no significant reduction in BMD, BMD in the upper arms, RFN, and spine were significantly reduced across the cohort.

BMI and body weight returned to healthy values in the 5- and 10-year cohorts,; however, bone health appeared to be impaired compared to normal standards, suggesting that adolescent AN has an impact on long-term bone health. The prevalence of fractures in the study cohort was 36%, similar to the normal range of between 30% and 50% in the general female population. However, among the study participants one subset reported 4-6 fractures, an abnormally high number.

One unexpected finding, according to the authors, was that serum-insulin-like growth factor-1 (IGF-1) showed a strong correlation with BMD. IGF-1 is a circulating hormone that plays a critical role in childhood growth and is reported to have an anabolic effect on adults and is a primary mediator of the effects of growth hormone. These are important and concerning findings.

In an editorial in the same issue, Drs. Amy D. DiVasta and Catherine M. Gordon of Boston Children’s Hospital and Harvard Medical School point out that this study’s results once more remind clinicians  of the importance of helping teenagers with eating disorders “get on the road to recovery just as soon as possible.”