How do you know if you have osteoporosis and how do you prevent it?

Unlike many medical diagnoses, osteoporosis is one condition that doesn’t cause symptoms.  So unless a woman breaks a bone or has specific testing, she has no idea that she has it.   This makes managing the condition tricky.  Ideally, preventing it should be a priority and certainly we want to intervene before a fracture occurs.  And since millions of women are at risk for osteoporosis, this raises all sorts of issues as to the most cost-effective approach.  This has led to a series of guidelines about what tests women should have, when they should have them, and at what point medications should be initiated.

What is osteoporosis?

First of all, what is osteoporosis?  It is somewhat of an arbitrary diagnosis.  It basically means that the bones have become so thin and brittle they are at a high risk of breaking – roughly ten times the risk compared to a young healthy adult.  A 35-year old woman who trips and falls on the sidewalk has a low chance of fracturing a bone.  But a 75-year old woman who has osteoporosis would be ten times more likely to break a hip.  The bones become weak because, due to age and other factors, the overall  density of the bone declines.  The outer tough shell gets thinner and the internal, honeycomb, structure becomes more porous.

Estrogen plays a major role in keeping the bone cells healthy.  After menopause, the loss of estrogen causes a dramatic loss of bone cells, so women develop osteoporosis much earlier and generally more severely than men of the same age.  In particular, estrogen is crucial to keep the internal boney matrix from deteriorating.

How is osteoporosis diagnosed?

There are two basic ways we diagnose osteoporosis.  If a woman has a fracture caused by a minor fall (such as a ground-level, simple fall and not something from a high-impact event such as a car accident or skiing mishap) that causes a fracture in the spine, hip, or forearm, she is considered to have osteoporosis.

Osteoporosis is also diagnosed if there is evidence of a vertebral fracture on an x-ray.  These fractures are called compression fractures and occur because osteoporosis causes weakness of the inside of a vertebrae, making it susceptible to being “squashed” or compressed.  This type of fracture appears as a shortened and wedge-shaped vertebra on the x-ray.  If a woman is found to have a compression fracture of the spine it is assumed she has osteoporosis.  Interestingly, in many cases, women diagnosed with one of these are not aware that this has occurred.

In women who have not suffered a fracture, the only other way to diagnose osteoporosis is to perform a test that measures bone density.  Sophisticated CAT scans can do this, but the most common test is a DEXA test (dual energy X-ray absorptiometry).  This test uses a tiny amount of radiation and is able to quantify how dense the bones are.  If the bone density is two-and-a-half times thinner than a healthy young adult, this is considered to be osteoporosis.  The test result uses a value called a T-score and osteoporosis is present if the T-score is less than minus 2.5 (-2.5).  A normal T-score is less than -1.0.  A score between -1.0 and -2.5 would be consistent with osteopenia, which means the bones are thin, but not yet in the osteoporotic range.

When do you perform a DEXA?

This is a somewhat controversial subject and one that also is influenced by economic factors.  The current U.S. guidelines don’t recommend doing a DEXA scan until age 65, unless there is a reason to suspect a younger woman is at very high risk.  This would include women who have had a low-impact fracture, are very thin, are taking certain medications such as steroids, or who have other conditions known to cause bone thinness.

Most women around age 50 are presumed to have normal bone structures, so it is not cost-effective to routinely do bone density tests at this age.  However, since women who do not take HRT can expect to lose bone rapidly, over the ensuing 5 years, many doctors feel that obtaining a baseline bone density before age 65 is warranted.

When do you treat osteoporosis?

Women who have been diagnosed with osteoporosis are advised to start some form of medication to slow down the loss of bone and prevent a future fracture.  There are multiple drugs approved for treatment and I discuss these in detail in my book, The Estrogen Question: Know Before You Say “no” to HRT.  Like any treatment, there are pros and cons to the various options and the choice depends on a woman’s personal medical history and preferences.

When do you treat osteopenia?

It seems intuitive that the best way to prevent a fracture is to prevent osteoporosis in the first place.  Getting adequate calcium and vitamin D in every stage of life is critical to build and maintain a strong bone structure.  Weight bearing exercise is also very important.  But even with these measures, women will lose a substantial amount of bone as they approach menopause.  In fact women in perimenopause begin to lose bone rapidly and within 7 years lose up to 10% of their bone mass.

Taking estrogen at this time can significantly curb this loss, but unfortunately estrogen is not approved specifically for this use in the U.S.  However, estrogen is approved for treatment of hot flashes, and women who take hormone replacement for this reason will get the valuable added benefit of helping preserve their bones.

Similarly, the other drugs used to treat osteoporosis are not approved as a preventative measure to avoid perimenopausal bone loss.  The guidelines are very specific about when these drugs should be initiated, and generally it is only when the bones have become so severely osteopenic there is a high risk of a fracture.

How do you determine if a woman is at “high risk” for a fracture?

The most common way that this is determined is by taking into account various factors that predispose women to developing osteoporosis.  This can be accomplished by using a software tool called the FRAX calculator.  Attributes such as a woman’s weight, age, ethnicity, smoking history, family history, and hip bone density score are plugged into an online questionnaire and the FRAX tool does an analysis of all of these factors.  The report then gives a FRAX score, which estimates the risk of a future fracture.  If a woman’s risk of a hip fracture is over 3% or a risk of any fracture over 20% in the ensuring ten years, drug treatment is advisable

How reliable are the assessment tools?

The DEXA scans and the FRAX scores have been shown to correlate quite well with the risk of fractures when the results are markedly abnormal.  But like with any test there are false positives and false negatives.  This became apparent when it was noticed that almost half of women diagnosed with a compression fracture of the spine had DEXA scans that were not in the osteoporotic range.  This is one reason why many experts in menopause also encourage women to have an x-ray of their spine when they have a DEXA and this can be done with the modern DEXA machines.

Another refinement in assessing fracture risk is the addition of a relatively new test, the VBS or vertebral bone structure test. This also can be performed with a DEXA machine equipped with this type of software.  Instead of just measuring the overall density of the bone, this test measures the degree of porosity inside the bone.  The more porous the bone, the greater its internal weakness.  The recent FRAX calculator tools use this additional information in calculating a woman’s fracture risk.

Future directions

There has been a great deal of emphasis on discovering new treatments for osteoporosis, but it seems we are lagging in our efforts to be more proactive in preventing it.  This should be a major focus.  Many of the non-hormone drugs for treating osteoporosis have been shown to be preventative, but concerns have been raised about using these drugs for long-term treatment.  So prescribing them for perimenopausal women, who can expect to live 20 to 30 years beyond menopause is problematic.

Despite its efficacy, estrogen therapy is not considered am option for preventing osteoporosis.  This is because of concerns of potential cardiac risks which arose from the WHI study.  However, as noted in my book and previous blogs, the WHI study basically assesses estrogen use in older postmenopausal women. Most experts in menopause now agree that estrogen therapy instituted in newly menopausal women carries very little cardiac risk and, in fact, actually appears to prevent heart disease.

In my opinion, taking estrogen off the table as a means to prevent osteoporosis has caused more harm than good for millions of women who would have benefited from taking it to preserve their bone quality for later life.