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Medical Author:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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Medical Editor:

Dennis Lee, MD

Dennis Lee, MD

Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.

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Medical Editor:

Catherine Burt Driver, MD

Catherine Burt Driver, MD

Catherine Burt Driver, MD, is board certified in internal medicine and rheumatology by the American Board of Internal Medicine. Dr. Driver is a member of the American College of Rheumatology. She currently is in active practice in the field of rheumatology in Mission Viejo, Calif., where she is a partner in Mission Internal Medical Group.

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In this Article

• What is osteoporosis?
• What are osteoporosis symptoms and signs?
• What are the consequences of osteoporosis?
• Why is osteoporosis an important public health issue?
• What factors determine bone strength?
• What are osteoporosis risk factors and causes?
• How is osteoporosis diagnosed?
• Who should have bone density testing?
• What is the treatment for osteoporosis, and can osteoporosis be prevented?
• Exercise, quitting cigarettes, and curtailing alcohol
• Calcium supplements
• Vitamin D
• Hormone therapy (hormone replacement therapy, menopausal replacement therapy)
• Medications that prevent bone loss and breakdown
• Choosing an osteoporosis medication
• Prevention of osteoporosis caused by long-term corticosteroids
• Monitoring osteoporosis therapy medication
• Prevention of hip fractures in elderly people with osteoporosis
• Osteoporosis At A Glance
• Find a local Internist in your town

What factors determine bone strength?

Bone mass (bone density) is determined by 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, which in turn are sometimes modified by environmental factors and medications. For example, men have a higher bone density than women, and African Americans have a higher bone density than Caucasian or Asian Americans.

Normally, bone density accumulates during childhood and reaches a peak by around age 25. Bone density then is 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.

Estrogen is important in maintaining bone density in women. When estrogen levels drop after menopause, loss of bone density 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. The accelerated bone loss after menopause is a major cause of osteoporosis in women, referred to as postmenopausal osteoporosis.

What are osteoporosis risk factors and causes?

The following are factors that will increase the risk of developing osteoporosis:

• Female gender



• Caucasian or Asian race



• Thin and small body frame



• 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



• Malabsorption (nutrients are not properly absorbed from the gastrointestinal system) from conditions such as celiac sprue



• Low estrogen levels in women (such as occur in menopause or with early surgical removal of both ovaries)



• Low testosterone levels in men (hypogonadism)



• Chemotherapy that can cause early menopause due to its toxic effects on the ovaries



• Amenorrhea (loss of the menstrual period) in young women associated with low estrogen and osteoporosis; amenorrhea can occur in women who undergo extremely vigorous exercise training and in women with very low body fat, for example, women with anorexia nervosa



• Chronic inflammation, due to chronic diseases such as rheumatoid arthritis or liver diseases



• Immobility, such as after a stroke, or from any condition that interferes with walking



• Hyperthyroidism, a condition wherein too much thyroid hormone is produced by the thyroid gland (as in Grave's disease) or is ingested as thyroid hormone medication



• Hyperparathyroidism is a disease wherein there is excessive parathyroid hormone production by the parathyroid gland, a small gland located near or within the thyroid gland. Normally, parathyroid hormone maintains blood calcium levels by, in part, removing calcium from the bone. In untreated hyperparathyroidism, excessive parathyroid hormone causes too much calcium to be removed from the bone, which can lead to osteoporosis.



• When vitamin D is lacking, the body cannot absorb adequate amounts of calcium from the diet to prevent osteoporosis. Vitamin D deficiency can result from lack of intestinal absorption of the vitamin such as occurs in celiac sprue and primary biliary cirrhosis.
  
  
• Certain medications can cause osteoporosis. These include long-term use of heparin (a blood thinner), antiseizure medications such as phenytoin (Dilantin) and phenobarbital, and long-term use of oral corticosteroids (such as prednisone).