Bone density test

Bone density is an index that evaluates the mineral components of bone, such as calcium (bone mass), as the amount per unit area on an X-ray image. It is calculated as the degree of relative deviation from the overall average, taking into consideration background factors such as age, sex, and race.

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Human bone mass changes with age. In women, bone mass increases significantly around the onset of menstruation and peaks at around 18 years of age. In men, peak bone mass is reached around age 20. Afterward, bone mass remains relatively stable or slightly declines in both men and women until the early 40s, after which bone density begins to noticeably decrease. Bone density drops sharply, particularly in women upon reaching menopause. Men also begin to see a decline in bone mass as they age. The age-related decrease in bone mass is associated with: 1) a decline in the function of osteoblasts (bone-forming cells); 2) decreased calcium absorption from the intestinal tract; 3) a decrease in vitamin D within the body; and 4) estrogen deficiency due to menopause.

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When bone density decreases and bones become fragile, fractures become more likely. If elderly individuals suffer from osteoporosis due to bone loss, the risk of triggering a fracture from events such as falls increases significantly. Common fractures in the elderly include femoral neck fractures and vertebral compression fractures. Both of these severely impair physical support and mobility, frequently resulting in individuals becoming bedridden.

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It is not just an issue for the elderly. When bone density declines, people often first begin to feel a chronic, dull pain in the back or lower back. As the deterioration of bone quality progresses, the pain becomes sharp. This occurs because nerves are stimulated by bone deformation known as spondylosis. With further decreases in bone density, vertebral compression fractures ultimately occur, causing the lower back or spine to curve and interfering with daily life. Therefore, chronic lower back or back pain may be a yellow warning light for osteoporosis.

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Undergoing a bone density test allows for the early detection of osteoporotic changes before subjective symptoms such as lower back pain develop. If an abnormal decrease in bone mass is discovered through a bone density screening, its progression can be prevented by taking appropriate measures. This not only prevents lower back and back pain as well as spinal deformation, but also prevents functional decline in the limbs, gait disturbances, and bedridden states caused by fractures in old age.

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While 90% of osteoporosis cases are primary osteoporosis with no clear cause, undergoing a bone density test can sometimes reveal underlying medical conditions that cause secondary osteoporosis, which has an identifiable cause. In such cases, treating the underlying disease can also help reverse osteoporosis.

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If a decrease in bone mass is found through a bone density test, the fundamental approach is to review lifestyle habits, such as increasing the intake of calcium and vitamin D and committing to appropriate daily exercise. Furthermore, excellent therapeutic medications, such as bisphosphonates, are now available, and taking them orally can actively slow down the progression of osteoporosis.

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Detecting signs of osteoporosis early through a bone density test and formulating bone-strengthening strategies from a young age is essential for ensuring a high quality of life in old age.