Purpose: Low areal bone mineral density (aBMD) is a well-known consequence of anorexia nervosa (AN). However, the impact of reduced energy expenditure on bone metabolism is unknown. This study assessed the effects of energy deficiency on bone remodelling and its potential interactions with glucose homeostasis and adipose tissue-derived hormones in AN, a clinical model for reduced energy expenditure.
Methods: 50 women with AN and 50 age-matched controls (mean age 18.1±2.7 and 18.0±2.1 years respectively) were enrolled. aBMD were determined with DXA. Resting energy expenditure (REEm), a marker of energy status, was indirectly assessed by calorimetry. Bone turnover markers, undercarboxyated osteocalcin (ucOC), parameters of glucose homeostasis, adipokines and growth factors were concomitantly evaluated.
Results: AN patients presented low aBMD at all bone sites. REEm, bone formation markers, ucOC, glucose, insulin, HOMA-IR, leptin and, IGF-1 were significantly reduced, whereas the bone resorption marker, leptin receptor (sOB-R) and adiponectin were elevated in AN compared with CON. In AN patients, REEm was positively correlated with weight, BMI, whole body (WB) fat mass, WB fat-free soft tissue, markers of bone formation, glucose, insulin, HOMA-IR, leptin, and IGF1, and negatively correlated with the bone resorption marker and sOB-R. Biological parameters, aBMD excepted, appeared more affected by the weight variation in the last 6 months than by the disease duration.
Conclusions: The strong interrelationships between REEm and bone remodelling, glucose homeostasis and adipokines underscore the importance of preventing energy deficiency to limit short- and long-term bone demineralisation and hormonal alterations in AN patients.
Funding: This work was supported by the Centre Hospitalier Regional Universitaire (CHRU) of Montpellier (AOI UF 8751 and UF 8854) and a grant from the Société Française dEndocrinologie Pédiatrique (SFEDP).
01 Oct 2015 - 03 Oct 2015