Positive effects of brown adipose tissue on femoral bone structure.

Abstract

Recent studies suggest a link between brown adipose tissue (BAT) and bone. The purpose of our study was to investigate the effects of BAT on femoral bone structure. We studied 105 patients (19 m, 86 f. mean age 45.5±16.1 years) who underwent F18-FDG positron emission tomography/computed tomography (PET/CT) for benign etiologies (n=20) or follow-up of successfully treated malignancies (n=85); mean time between PET/CT and last form of treatment was 14.8±18.0 months. BAT volume by PET/CT; femoral bone structure by CT (total femoral cross-sectional area (CSA), cortical CSA); and thigh muscle CSA and thigh subcutaneous fat CSA by CT was assessed. There were positive correlations between BAT volume and total femoral CSA and cortical CSA, independent of age, BMI and history of malignancy (p<0.05). BAT volume correlated positively with thigh muscle CSA and thigh fat CSA (p<0.05). When total femoral CSA was entered as a dependent variable and BAT volume, age and BMI as independent variables in a forward stepwise regression model, BAT volume was the only predictor of total femoral CSA. When femoral cortical CSA was entered as a dependent variable and BAT volume, age and BMI as independent variables, BAT volume was the only predictor of femoral cortical CSA. BAT volume is a positive predictor of femoral bone structure and correlates positively with thigh muscle and subcutaneous fat, possibly mediated by muscle. These results provide further evidence of a positive effect of BAT on bone.