Bone Parameters in Anorexia Nervosa and Athletic Amenorrhea: Comparison of Two Hypothalamic Amenorrhea States

We have reported low bone mineral density (BMD), impaired bone structure, and increased fracture risk in participants with anorexia nervosa (AN) and normal-weight oligoamenorrheic athletes (OAs). However, data directly comparing compartment-specific bone parameters in participants with AN, OAs, and controls are lacking.

A total of 468 female participants 14 to 21.9 years old were included: 269 with AN, 104 OAs, and 95 normal-weight eumenorrheic controls. Dual-energy x-ray absorptiometry was used to assess areal BMD (aBMD) of the whole body less head (WBLH), spine, and hip. High-resolution peripheral quantitative computed tomography was used to assess volumetric BMD (vBMD), bone geometry, and structure at the non-weight-bearing distal radius and weight-bearing distal tibia.

Participants with AN had lower WBLH and hip aBMD z scores than OAs and controls (P < 0.0001). Participants with AN and OAs had lower spine aBMD z scores than controls (P < 0.01). At the radius, total and cortical vBMD, percentage cortical area, and thickness were lower in the AN and OA groups than in controls (P ≤ 0.04); trabecular vBMD was lower in participants with AN than controls. At the tibia, participants with AN had lower measures for most parameters compared with OAs and controls (P < 0.05); OAs had lower cortical vBMD than controls (P = 0.002). Participants with AN and OAs had higher fracture rates than controls. Stress fracture prevalence was highest in OAs (P < 0.0001); nonstress fracture prevalence was highest in participants with AN (P < 0.05).

AN is deleterious to bone at all sites and both bone compartments. A high stress fracture rate in OAs, who have comparable WBLH and hip aBMD measures to controls, indicates that BMD in these women may need to be even higher to avoid fractures.