Aging & Health A to Z

Osteoporosis

Basic Facts & Information

What is Osteoporosis?

Osteoporosis refers to the thinning of the bones, loss of bone density, and increasingly fragile bones. Osteoporosis is a process that develops gradually over many years as we age.

Our bones are made of living tissue. Our bodies are constantly renewing and repairing bone tissue through the action of bone cells that break down old damaged bone allowing the osteoblasts to produce healthy new bone in its place. This process of bone removal and renewal is called “bone remodeling”. Bone remodeling occurs in response to physical stress or damage—from exercise or simply from the weight of our bodies—and to hormones and other chemicals circulating in our blood. Our damaged bones are repaired and stay healthy thanks to bone remodeling.

As we age, however, bone remodeling becomes unbalanced, and more bone is lost than new bone is formed. This “age-related bone loss” is especially noticeable in women after menopause, when the hormone estrogen is no longer produced. Older women can lose up to 7% of their bone every year. Older men also lose bone, as less of the hormone testosterone is produced, although the bone loss is more gradual in men.

Often osteoporosis has no symptoms and you may be unaware that your bones have become thin and unstable.

Osteoporosis Can Lead to Fractures

The first sign that bones are thin or fragile may be a sudden fracture after a minor bump, strain, fall, bend, or even a cough. A fracture usually means that your osteoporosis is serious.

Hip fractures leave about half of patients with walking problems. About one quarter of people with hip fractures are unable to live independently afterwards, and a hip fracture is one of the main reasons that older people move into nursing homes. Spinal fractures also reduce quality of life, and may make it hard to bathe, dress, or walk independently. Such fractures also increase the risk of a fall.  

The Most Common Types of Bone Loss

There are three commonly types of bone thinning:

• Osteopenia: moderate bone loss with an increased risk of fracture.
• Osteoporosis: more severe bone loss associated with a higher risk of fracture.
• Osteomalacia: much less common than osteoporosis or osteopenia, osteomalacia refers to problems of bone mineralization. It causes pain, muscle weakness, and fractures. In older adults, a deficiency of vitamin D is at the root of most cases, but it also may result from overuse of some medications, kidney or liver disease, or problems absorbing nutrients through the intestines.

How Common is Osteoporosis?

Osteoporosis is the most common bone disease, affecting approximately 10 million people of all ethnic backgrounds in the US. Another 33 million people have less severe bone loss (osteopenia). Osteoporosis affects men and women, but most cases—about 80%—are diagnosed in women. Research has found that about one out of every five American women over the age of 50 already has osteoporosis. 

Updated: March 2012
Posted:  March 2012