With osteopenia, how long does it take to lose bone, like wrists to become thinner?

Osteopenia: Osteopenia probably means nothing at your age and you do not need to worry or have any clinical exams or bone density studies. Are you so concerned because family members have been diagnosed as having osteoporosis? If so you should still not have any worries. Bones can become fragile later in life but bone loss does not include thinning other than inside the main part of the wrist or other bone.