Part 1: Understanding Osteoporosis

Yes, the correct answer is "long-standing testosterone deficiency."

A deficiency of testosterone is a significant risk factor for hip fracture in elderly men. This deficiency can lead to an increase in bone turnover with bone formation at levels below normal leading to a net loss of bone. This problem can be corrected in men with testosterone replacement therapy, just as women can partake in estrogen replacement therapy (to be discussed later in this course).

A serious problem in men which accounts for almost 50% of their cases of osteoporosis is "idopathic" osteoporosis - meaning there is no known cause. Age-related bone loss in men can be due to:

the decrease in osteoblast function as a person ages
spending less time engaging in physical activity such as exercise
a decrease in consumption of calcium, coupled with the inability of their body to absorb calcium optimally
the decrease in testosterone levels which occurs with age