Bone growth is an ongoing process that relies on a balance of new bone deposition and old bone resorption. These processes are carried out by two types of cells: osteoblasts, which help generate new bone tissue, and osteoclasts, which break down aged bone tissue. If the balance between osteoblast and osteoclast activity becomes dysregulated, bone mass and density can fluctuate and become too high or too low. A number of conditions or disorders can lead to decreased bone density.
Aging
Aging is a natural process that decreases bone density. As a person ages, the relative activity levels of osteoblasts and osteoclasts change, so the osteoclasts become more active as the person gets older. The result is a loss of bone mass and a decrease in bone density. The University of Washington indicates that bone density loss is progressive, starting at age 20 and persisting throughout a person's entire life. The loss of bone density increases the risk of stress fractures due to bone weakness. The rate at which bone loss occurs during aging can depending on a number of lifestyle factors. Maintaining an active lifestyle and performing a fitness routine with strength training coupled with a healthy diet rich in vitamins and minerals can help maintain bone density.
Hormonal Changes
Hormonal imbalance or a rapid change in hormone levels is another potential cause of low bone density. Hormones like estrogen, a female hormone produced in the ovaries during a woman's fertile life, help regulate bone density. Specifically, estrogen signals for an increase in bone density and helps maintain a woman's bone density. Women entering menopause experience a dramatic drop in estrogen levels because their ovaries begin to shut down and stop producing estrogen. This loss of estrogen is followed by a loss of bone density and increased risk of bone fracture. The University of Washington indicates that estrogen therapy can effectively improve bone density in post-menopausal women.
Osteolytic Bone Metastases
Some types of cancer can also lead to a decrease in bone density. A number of cancer types, such as breast cancer, can spread or metatasize to the bone, disrupting the normal process of bone turnover. Breast cancer readily metastasizes to bone tissue. Once the breast cancer cells have colonized on the bone, the cancer attacks the bone tissue with the help of osteoclasts, leading to a breakdown of the bone structure, reports a study published in the"Clinical Orthopaedics and Related Research" in 2003. For this reason, patients with metastatic breast cancer may have decreased bone density and an increased risk for bone fracture due to bone damage from tumor growth.
