Endocrine Abstracts

JOINT772

Anorexia nervosa (AN) is a psychiatric disorder characterized by self-imposed fasting leading to significant weight loss and consequently nutrient deficiencies that disrupt the bone metabolism. Also, the catabolic processes in muscle and adipose tissue are associated with bone loss. Curiously, caloric restriction leads to marrow adipose tissue (MAT) expansion, which is associated with low bone mineral density (BMD). This cross-sectional observational study aimed to evaluate MAT in the tibia and explore the relationships between 3D shaper parameters, dual-energy-X-ray absorptiometry (DXA), body composition, and trabecular bone score (TBS). Both groups underwent blood sampling, DXA scans, TBS assessments, magnetic resonance ¹H spectroscopy of the tibia, and 3D shaper analysis. The study included 12 women with AN, monitored by a multidisciplinary team, and 11 healthy controls (C), matched by age (C:25. 6±8. 6; AN:24. 2±10. 0 years) and height (C:1. 62±0. 05; AN:1. 59±0. 09 m). The total MAT was significantly higher in the AN (93. 2±6. 4 %) than C (87. 0±8. 5 %). Total hip (TH) BMD (C:0. 96±0. 07; AN:0. 81±0. 16 g/cm²), TH Z-score (C:-0. 32±0. 57; AN:-1. 49±1. 18), femoral neck (FN) BMD (C:0. 98±0. 06; AN:0. 81±0. 17 g/cm²), and FN Z-score (AN:-0. 35±0. 57; C:-1. 21±0. 99) were significantly lower in AN. Additionally, fat mass index was reduced in women with AN (C:7. 70±1. 44;AN:5. 56±1. 96 kg/m², P < 0. 01), while the appendicular lean mass index (ALMI) was similar between both groups (C:5. 88±0. 71; AN:5. 68±1. 25 kg/m²). The 3D shaper parameters tended to be lower in the AN [e. g. cortical sBMD total (C:151±14; AN:129±26 mg/cm²) and trabecular vBMD total (C:194±25; AN:153±53 mg/cm³)]. A negative association was observed between MAT and FNBMD (R²=0. 3, P = 0. 02). There was association between total cortical volumetric BMD (vBMD) (P = 0. 02, R²=0. 26), cortical surface BMD (P = 0. 01, R²=0. 31), integral vBMD (P = 0. 03, R²=0. 24), and TBS. FN Z-score had a trend of association with ALMI (P = 0. 05, R²=0. 19) and was related with FMI (P = 0. 04, R²=0. 20). In addition, it was observed a negative relationship of total cortical thickness with ALMI (P = 0. 04, R²=0. 21) and FMI (P = 0. 04, R²=0. 21). The results suggest that women with AN exhibit reduced BMD compared to healthy controls, beside compromised 3D-DXA parameters of the proximal femur and decreased TBS. The present study is the first to show that the tool 3D shaper potentially can detect bone impairment in AN. Moreover, it suggests that fat mass has a stronger association with FN BMD than lean mass in AN and confirms a negative relationship between MAT and bone mass in AN.