Rheumatoid Arthritis and Osteoporosis

Question

I have had RA for about 6 years on mtx 15, pred 3 mg, plaq 400 mg and various other nsaids, along with vitamins including 1200 mg of calcium a day. Last December 2002 I had a dexa scan which showed a T-score of -0.61 (94% of young normal values) and Z-score of +0.14 (102% of age match normal values in the lumbar spine and pelvis. I have been having very severe lower back pain and pain in my hips for the past three months…thought maybe it was a new mattress problem, as my right hip would be totally numb and very painful when I would wake up. I moved to the sofa. I went and saw my internist who order Lumbar spine x-rays and pelvis x-rays. I have severe osteoarthritis at L5 with facet hypertrophy throughout the lower spine. Pelvis ok. But, the worse part is my spine has moderate osteoporosis. L3 thorugh 5 have no trabecula left and are very transparent. My question is how can someone with such a great Dexa just 13 months ago, go to plain films like this? I am 51 and have been trying to get through menopause this past year, with very irregular periods. I take no hormones. There is no family history of osteoporosis. My estrogen level in October was normal. Thank you for your time.

Answer

The DEXA scan can be fooled to give a falsely normal result in the lumbar spine if there are large osteophytes (bone spurs) due to degenerative arthritis. The osteophytes interferes with the DEXA beam.

Alan Matsumoto, M.D.

About Alan Matsumoto, M.D.

Part-time Faculty, Division of Rheumatology
Johns Hopkins University