Dear Dr. Roach: I am an active, 5-foot-2-inch, 125-pound, 72-year-old Caucasian woman without a history of known osteoporotic risk factors, other than demographic ones. I exercise daily, eat calcium through food, take 2,000 units of vitamin D, and follow a Mediterranean-style diet.
My last dual-energy X-ray absorptiometry (DXA) scan showed a T-score in my spine of -3.3 and a T-score in my hip of -2.7. My Z-scores were 0, and my FRAX score showed a 15.4% overall risk of fracture, with a 4.4% risk for a hip fracture in the next 10 years. Overall, my bone density went down 6.5% for my spine and 5% for my hip, compared to three years earlier.
My primary care physician has recommended starting bisphosphonates. My preference would be to postpone medication for at least a year, while I work with a dietitian and a physical therapist to refine my exercise program and try to build bone more effectively. But I also don’t want to take foolish chances with a spine or hip fracture. At my request, I received a referral to a specialist, but I cannot see her for four months.
How accurate are the results of a DXA scan? I have scoliosis from childhood; could it affect the accuracy of the test results? Would any other imaging, blood or urine tests be appropriate to provide additional information or indicate if there are other causes of bone loss, besides age and gender?
A.M.
The most important number here is the FRAX score, which combines your clinical risk (age, gender, height and weight, ethnicity, steroid use, smoking, previous fractures, alcohol use, etc.) and your bone density results from your DXA scan to provide an estimate of the overall fracture risk and the most dangerous type of fractures: hip fractures. It’s freely available at frax.shef.ac.uk/FRAX/tool.aspx.
Your results are above the recommended threshold for medication, which is either a total-fracture risk of 20% or a hip-fracture risk of 3%. Among the different options, most experts would choose a bisphosphonate drug like alendronate, based on decades of experience and strong data. However, a very low T-score (worse than -3) makes some experts choose a different type of agent — a PTH analogue like teriparatide. Your scores have dropped a lot quickly, so I definitely recommend treatment.
I do understand why you are hesitant. These drugs can cause more harm than good when they are not used correctly, and many of my patients are concerned after reading others’ experiences. But when used properly, generally for three to five years, they are very good at preventing fractures.
Scoliosis can affect the accuracy of DXA tests, but the tests usually underestimate the severity of osteoporosis.
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