2009 February | Female Athlete Triad Coalition

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Distal radius in adolescent girls with anorexia nervosa: trabecular structure analysis with high-resolution flat-panel volume CT

By Bredella MA, Misra M, Miller KK et al. in Radiol 2008; 249(3):938-946.

This study investigated the microarchitecture of the trabecular bone network in adolescents with mild anorexia nervosa (body weight>80% ideal weight for age). Trabecular bone is found in vertebral bodies and extremities of long bones. It is composed of a complex network of trabeculae and looks like a sponge -hence the term ‘spongious bone’ to describe trabecular bone. The trabecular bone microarchitecture has been relatively less well studied than cortical bone due to the limitations of bone imaging techniques in vivo. The size of the trabeculae varies between 50 to 300 µm, which explains why techniques such as DXA or pQCT cannot be used to analyze the trabecular network. The authors used flat panel volume computed tomography which provides a resolution of 150µm³. The authors demonstrated that trabecular bone microarchitecture was affected in girls with mild anorexia nervosa despite normal BMD (as measured by DXA), and that the anorectic girls had thinner trabeculae with larger spaces between the trabeculae than normal-weight girls. These adaptations are similar to what is observed after menopause, leading to increased skeletal fragility. This study showed that trabecular bone microarchitecture was affected before a decrease in BMD could be detected by DXA. Given that the subjects suffered from mild anorexia nervosa, these findings are of great concern for adolescents who suffer from more severe forms of the disease.

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Calcium and vitamin D supplementation decreases incidence of stress fractures in female navy recruits

By Lappe JM, Cullen D, Haynatzki G et al. in J Bone Miner Res 2008; 23(5):741-749.

This randomised double-blind placebo-controlled study investigated the effect of 2000 mg calcium and 800 IU vitamin D of daily supplementation on the incidence of stress fractures in 5,201 female military recruits. Supplementation was initiated at the beginning of the 8-week basic training program. A total of 3,700 recruits completed the study and stress fracture incidence was 21% lower in the treated group (6.8% vs. 8.6% in the placebo group, p=0.02). Most of the fractures were at the tibia or fibula. Unfortunately vitamin D levels could not be measured. The recruits had a median dairy intake <1 serving/day, which provides ~300 mg of calcium. This could partly explain why the supplementation was so efficient. During training 2,786 subjects reported having no menstrual periods. The risk of fracture in those with amenorrhea was 91% higher than those with one or more menstrual periods during training (RR, 1.91, 95% CI = 1.47-2.47, p<0.0001). The only factor that was protective of fracture was history of exercise. Although the outcomes of the study – and the sample size – are impressive, the mechanisms by which the supplementation helped to prevent stress fractures are still unclear.

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The Menstrual Cycle and Adolescent Health

Edited by, Catherine M. Gordon, Corrine Welt, Robert W. Rebar, Paula J.A. Hillard, Martin M. Matzuk, and Lawrence M. Nelson in the Annals of the New York Academy of Sciences, June 2008, Vol. 1135

A group of basic scientists, clinicians, clinical investigators, psychologists, patient advocacy groups, and representatives from professional societies and governmental agencies met at the National Institutes of Health in October, 2007 with the long-term goal of having the menstrual cycle accepted and understood as a marker of general health in adolescent girls.

A compilation of this meeting is presented in this special issue, which is divided into five sections: 1) The Normal Adolescent Menstrual Cycle, 2) Disease Processes and the Adolescent Menstrual Cycle, 3) Bridging Normal and Abnormal Menstrual Cycle Processes,4) Modern Dilemmas and the Adolescent Menstrual Cycle, and 5) Conclusions and Reflections for Future Research in this Area.