Bones are the framework for your body. Bone is living tissue that changes constantly, with bits of old bone being removed and replaced by new bone. You can think of bone as a bank account, where you make “deposits” and “withdrawals” of bone tissue.
During childhood and adolescence, much more bone is deposited than withdrawn, so the skeleton grows in both size and density. Up to 90 percent of peak bone mass is acquired by age 18 in girls and age 20 in boys, which makes youth the best time to “invest” in your bone health.
A bone density scan can detect thinning bones at an early stage. If you already have osteoporosis, bone scans can also tell you how fast the disease is progressing.
But an abnormal bone scan can create as many questions as it answers. Who should get a bone density scan, and what do the results mean? If your bone density is below normal, what can you expect, and what should you do?
The amount of bone tissue in the skeleton, known as bone mass, can keep growing until around age 30. At that point, bones have reached their maximum strength and density, known as peak bone mass. In women, there tends to be minimal change in total bone mass between age 30 and menopause. But in the first few years after menopause, most women experience rapid bone loss, a “withdrawal” from the bone bank account, which then slows but continues throughout the postmenopausal years. This loss of bone mass can lead to osteoporosis. Given the knowledge that high peak bone density reduces osteoporosis risk later in life, it makes sense to pay more attention to those factors that affect peak bone mass.
Factors Affecting Peak Bone Mass
Peak bone mass is influenced by a variety of genetic and environmental factors. It has been suggested that genetic factors (those you were born with and cannot change, like your gender and race) may account for up to 75 percent of bone mass, while environmental factors (like your diet and exercise habits) account for the remaining 25 percent.
Gender: Peak bone mass tends to be higher in men than in women. Before puberty, boys and girls acquire bone mass at similar rates. After puberty, however, men tend to acquire greater bone mass than women.
Race: For reasons still not known, African American females tend to achieve higher peak bone mass than Caucasian females. These differences in bone density are seen even during childhood and adolescence.