MEASUREMENT OF FOREARM BONE-MINERAL DENSITY BY X-RAY ABSORPTIOMETRY -COMPARISON WITH OTHER SKELETAL SITES

In order to validate a new technique to measure bone mineral density ( BMD) of the forearm with a single X-ray absorptiometry device (DTX 100 ), we have measured the BMD of 195 women, aged 32 to 83 years, free of metabolic bone disease, simultaneously on two devices: 1. BMD of the ultradistal radius and of the distal radius and ulna on DTX 100, Osteo meter (R), 2. BMD of the lumbar spine, of the proximal femur, of the w hole body and of the distal and ultradistal radius by dual X-ray absor ptiometry (DXA) on an Hologic 2000(R) device. The precision of DTX, as sessed by 5 repeated measurements on 9 volunteers, was 1% for the dist al site and 2% for the ultradistal site. There was a high correlation (r = 0.93) between radial BMD measurement by DTX and Hologic 2000. Cor relations between forearm BMDs measured by DTX and whole body BMD were as high (r = 0.80-0.82) as between whole body BMD and lumbar spine (r = 0.82), femoral neck (r = 0.77) and femoral trochanter (r = 0.76). A gerelated bone loss measured by DTX was 27% and 31% at the distal and ultra distal radius respectively, as compared to 17% for the lumbar sp ine, 21% for the femoral neck and 16% for the whole body BMD. In a gro up of 20 untreated osteoporotic women with vertebral fractures, forear m BMD was as sensitive (T score of -3.1 and -2.9 for distal and ultra distal) as was lumbar spine (T = -2.9) and femoral neck (T = -2.5). In conclusion measurement of forearm bone mineral density by DTX, which is simple, fast, and relatively inexpensive, appears to be an interest ing method for the diagnosis of osteoporotic patients.