What Factors Determine Bone Strength?

Bone mass (bone density) is the amount of bone present in the skeletal structure. Generally, the higher the bone density, the stronger the bones. Bone density is greatly influenced by genetic factors and can be affected by environmental factors and medications. For example, men have a higher bone density than women. African Americans have a higher bone density than Caucasian or Asian Americans. Normally, bone density accumulates during childhood and reaches a peak by around 25 years of age. Bone density is then maintained for about 10 years. After age 35, both men and women will normally lose 0.3%-0.5% of their bone density per year as part of the aging process.

Menopause, Estrogen, and Osteoporosis

Estrogen is important in maintaining bone density in women. When estrogen levels drop after menopause, bone loss accelerates. During the first five to 10 years after menopause, women can suffer up to 2%-4% loss of bone density per year! This can result in the loss of up to 25%-30% of their bone density during that time period. Accelerated bone loss after menopause is a major cause of osteoporosis in women.

What Are the Risk Factors for Developing Osteoporosis?

• female gender
• Caucasian or Asian race
• thin and small body frames
• family history of osteoporosis (for example, having a mother with an osteoporotic hip fracture doubles your risk of hip fracture)
• personal history of fracture as an adult
• cigarette smoking
• excessive alcohol consumption
• lack of exercise
• diet low in calcium
• poor nutrition and poor general health

What Are the Risk Factors for Developing Osteoporosis? (continued)

• malabsorption (nutrients in the bowels are not properly absorbed)
• low estrogen levels
• chemotherapy
• loss of the menstrual period (amenorrhea)
• chronic inflammation
• immobility, such as after a stroke or any condition that interferes with walking
• hyperthyroidism (excessive thyroid hormone)
• hyperparathyroidism (excessive parathyroid hormone production causes too much calcium to be removed from the bone)
• vitamin D deficiency (vitamin D helps the body absorb calcium)
• certain medications can cause osteoporosis such as long-term use of heparin (a blood thinner), antiseizure medications phenytoin (Dilantin) and phenobarbital, and long-term use of oral corticosteroids (such as prednisone)