Bone density in osteopenic women: a modified distal radius density measurement procedure to develop an "at risk" value for use in screening women.

This study measured radial and lumbar spine bone density in postmenopausal white female patients with nontraumatic fractures and their age-matched controls. Bone density measurements were made with a single-beam densitometer. Distal radial bone density measurements were made at the site at which the radius and ulna are separated by 5 mm, which is approximately 5 mm from the distal radioulnar joint. Lumbar spine density was obtained using a dual-beam densitometer. Density at the commonly used "2/3" site near the midradius was also measured. Forty-six crush fracture osteoporotic patients, 35 hip fracture patients, and 20 osteopenic patients referred to the clinic for back pain or excessive bone loss but with no history of nontraumatic fracture were studied. Bone density values at all sites in the patient populations were statistically reduced from control values (p less than 0.01). At a mean age of 62 years, density of the midradius was 12% below the control value. However, both vertebral and distal radial densities ("5 mm" site) were 25% below control values. The spine/distal radius ratio remained constant. It was demonstrated that bone density at the modified distal radial site could be used to predict vertebral density in osteopenic patients. An "at risk" value useful in screening procedures was determined as that distal radius density value greater than or equal to 95% of all values from fracture patients--325 mg/cm2. It is concluded that distal radial density at the new "5 mm" site can be used in conjunction with midradius density as a preliminary test for both generalized and trabecular bone mass loss in women.