The bone that makes up your skeletal framework is a dynamic structure that is constantly evolving throughout your lifetime. Bone is composed of a complex matrix of minerals like calcium and phosphate, specialized molecules and proteins, and a distinct subset of bone-specific cells. The overall health of your bones is important for a number of essential biological processes, including your immune system and blood cell production. As you age, it is important to maintain healthy bones, which can be evaluated by your bone density.
Bone Building and Resorption
Your bones contain specialized cells that are responsible for building bone structure and breaking it down. Osteoblasts are cells that are responsible for building the complex structure of your bones in a process that is tightly regulated by small signaling molecules and proteins that tell them where and how much to build. Conversely, osteoclasts are the types of cells that break down bone to reshape it and allow blood vessels to grow and feed the bone tissue in a process called resorption.
Osteoporosis
When you are young, your osteoblast activity is much greater than your osteoclast activity, which allows for the growth of your bones and sustained bone density. As you age, the balance between osteoclast and osteoblast activities changes, which is why there is a decrease in bone density. When osteoblast activity becomes completely unregulated, your bones become holey and porous in a process called osteoporosis. According to MayoClinic.com, individuals who suffer from osteoporosis have bones that are brittle and weak, and are at increased risk for fracture. To determine your risks for developing osteoporosis, have bone density scans performed to assess the health of your bones.
Bone Density Scanning
While women are more at risk for developing osteoporosis, it does occur in men as well. Bone density scanning, also known as dual-energy x-ray absorption, or DEXA, is the standardized method for determining bone density. According to Medline Plus, women over the age of 65 and men of the age of 70 are at risk for having osteoporosis and should have their bone density evaluated. Your physician may order a bone density scan earlier if you have other risks, including smoking or alcohol addictions, chronic kidney disease, rheumatoid arthritis, family history of osteoporosis or have had a bone fracture after the age of 50.
T Score and Z Score
The bone density scan usually takes a picture of your lower spine and hip area and uses software to calculate your bone density. The results are reported as both a T score and a Z score. The T score is a value that compares your bone density to that of a healthy 30-year-old individual. A T score of zero means that your bone density is equal to that of a young adult, whilst a score of -2.5 or lower indicates osteoporosis. A Z score is similar to the T score, except that your bone density is compared to a healthy individual who is closer to your age. However, according to the Osteoporosis and Related Bone Diseases National Resource Center, older people who are healthy also lose some bone mass, so the Z score can be misleading and may not accurately reflect the status of your bone health.
