BRD2 and Osteopenia: Recent reports indicated that the increased FSH, although mild, could contribute to increased bone resorption and bone loss to some extent.(35) However, serum estradiol levels, which are felt to represent the major factor associated with bone loss in hypogonadal males,(36,37) were not significantly different between the hyponatremic and control rats, and the decreased bone-formation indexes argue against a high-turnover type of osteopenia.