Ask An Expert: Early Osteoporosis

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Ask An Expert: Early Osteoporosis

Question:

Why would some 44 year olds and still menstruating have osteoporosis? I had a bone density test, and now am taking Fosamax since there is osteoporosis in my lower back. What causes it to start so early?

Answer:

Osteoporosis is a common condition marked by weak bone that is prone to fracture. Until a fracture occurs, there are usually no symptoms. Most people with osteoporosis are diagnosed after having a fracture, or, preferably, after having a bone mineral density (BMD) test. This special type of X-ray can detect the presence of osteoporosis and guide treatment to prevent fractures in the future.

Osteoporosis is most common among post-menopausal women as it is highly associated with estrogen deficiency (a defining feature of menopause). However, it can occur before menopause in anyone with risk factors, including:

• A family history of osteoporosis

• Caucasian or Asian ethnicity (osteoporosis is less common in African-Americans)

• Low weight – thin people tend to have more osteoporosis than others

• Low calcium and vitamin D intake – because these are needed to form bone, low intake may increase the risk

• The presence of certain medical problems or medication use – for example, people with digestive diseases (who do not absorb vitamin D normally) and those who take corticosteroids are at higher risk

• Lack of weight-bearing exercise

• Excessive alcohol intake

• Smoking

• An over-active thyroid (or taking too much thyroid replacement hormone)

A prolonged period of time without menstruation can also increase the risk of early-onset osteoporosis. For example, females who are highly athletic or have an eating disorder may go months or years without having a period — estrogen levels tend to be low in these women, and if calcium and vitamin D intake are low over that stretch of time, bone density may never reach its full potential. Adolescents who diet and don't have periods are also at risk, even if they don't have anorexia nervosa or another eating disorder. One or more of these risk factors could explain why you have osteoporosis at such a young age.

However, despite all that is known about osteoporosis, there are still rare instances of early-onset disease in the absence of recognized risk factors. It's likely that some of these people have a genetic abnormality in bone formation — that is, they build less bone than they should. Because normal bone is constantly being broken down and formed, even a minor deficiency in bone formation can lead to osteoporosis over time.

There is much we still don't understand about osteoporosis — researchers are working hard to figure out better answers to questions like yours.

Robert Shmerling, M.D., is associate physician and clinical chief of rheumatology at Beth Israel Deaconess Medical Center and an associate professor in medicine at Harvard Medical School. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program and has been a practicing rheumatologist for over 25 years.

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Last updated:	January 24, 2007