Estrogen is essential to good bone density, meaning bones that are saturated with minerals and therefore less likely to break. As estrogen levels fall during menopause, bones can become weaker, leading to a greater risk of fracture, osteopenia (low bone mass), and osteoporosis (weak, brittle bones). A DEXA body scan, which measures bone-mineral density, can indicate whether someone is at risk for developing osteoporosis or experiencing a fracture.