Q and A: Bone Density Testing

Q:I have a local doctor and a Veterans Administration doctor, and they disagree about what to do with the results of my bone mineral density test. I am a white 78-year-old man, a non-smoker for 30 years, have a BMI of 24 and am very active, walking two to four miles daily.

I have not used steroids, I do not have a thyroid problem, but I have had esophagus problems. My only fractures were six ribs in 1973 after falling off a ladder. My t-scores on my DEXA bone density test were -1.1 at the wrist, -1.0 at the spine, -1.0 at the total hip and -1.9 at the hip neck alone. Do I need to take Fosamax (alendronate)? Or are calcium with vitamin D supplements enough?

A:In your case, a bone mineral density test was done to screen for osteoporosis. In general, doctors screen for osteoporosis in people at increased risk for osteoporosis, so that, if the test is positive, we may recommend therapy such as Fosamax and calcium to prevent an osteoporotic fracture.

From your history, factors that may increase your risk of osteoporosis include your race, age and past smoking, although your gender and physical activity decrease your risk, and I do not know if you have regularly consumed adequate dietary calcium and whether you drink more than socially.

Your test results are consistent with osteopenia, which is the in-between category between normal (t-scores higher than -1) and osteoporosis (t-scores lower than -2.5), noting that three of your four scores are nearly normal.

Your doctors disagree because there is controversy about what to do in the setting of osteopenia. I follow the National Osteoporosis Foundation guidelines, which recommend therapy with medicines such as Fosamax only when the t-score is less than -2. Given your relatively low risk and no history of unexplained fractures, I think it's reasonable to make sure you have enough calcium and vitamin D and recheck your bone density in two years.

Q:I am a 50-year-old woman who recently had a bone mineral density test. Although my spine is fine, I have osteopenia in my hips. My doctor advised me to increase my calcium intake and my weight-bearing exercise, and I did. We discussed taking Fosamax (alendronate) after menopause (I have no symptoms to date).

I was very surprised by the results. Why would the bone density in my hips be so different from that in my spine? Should I have other areas checked? Should I take Fosamax now?

A:The main purpose of bone mineral density testing is to measure bone strength and to diagnose osteoporosis. Osteoporosis is a very common problem in older women. Bones become brittle and susceptible to fracture. Our standard bone mineral density tests are performed at the hip and spine because hip and spine fractures can be more debilitating than fractures at other sites. It's common to have different measurements at the hip compared with the spine, and this may be due to the different basic structures of hip and spine bones.

Dr. Joan Neuner, an internal medicine specialist and osteoporosis researcher at the Medical College of Wisconsin, says that the standard bone mineral density tests are pretty good at predicting fractures, and given your age and test results, you have a less than 1% chance of breaking your hip in the next five years (and even less chance of breaking your spine). So, with this good news, keep up the calcium and exercise, and have your bone mineral density rechecked in about two years.

Julie L. Mitchell, MD, MS, is an Assistant Professor of Medicine at the Medical College of Wisconsin. She practices internal medicine at the Froedtert & Medical College General Internal Medicine Clinic - East. Her column appears in the Milwaukee Journal-Sentinel.