Final answer:
The disorder that involves the loss of bone density is osteoporosis, which is caused by an imbalance between bone resorption and bone formation, leading to weakened and brittle bones.
Step-by-step explanation:
The disorder that involves the loss of bone density is osteoporosis. This condition leads to weakened and brittle bones due to an imbalance in bone remodeling. Bone remodeling consists of bone resorption and bone formation, processes carried out by osteoclasts and osteoblasts, respectively. In osteoporosis, there is excessive bone resorption or insufficient bone formation, or sometimes both. This can be exacerbated by factors such as hormonal changes, diseases, and certain medications. Unlike osteoarthritis, which is a joint disorder resulting from the breakdown of cartilage and bone typically due to wear and tear, and rheumatoid arthritis and gout, which are inflammatory conditions, osteoporosis specifically refers to the decrease in bone density that can lead to fractures. It's a common misconception that bone mass does not decrease in men as they age, but this is false, as men can also experience decreased bone mass, though less commonly than women.