(HealthDay)—A postmenopausal woman who is 50 and has a normal bone density test may not need her next such test for 10 or even 15 years, according to research published in the June issue of Menopause.

Margaret Lee Gourlay, M.D., M.P.H., of the University of North Carolina at Chapel Hill, and colleagues studied data for 4,068 postmenopausal American women between the ages of 50 and 64 who took part in the ongoing Women's Health Initiative study. All of the women had undergone a test to assess their risk for fractures and osteoporosis. The women were not taking hormones, calcium, or vitamin D supplements, and had never had a fracture.

Among women whose tests showed no signs of osteoporosis, it took nearly 13 years for just 1 percent of the youngest women, and almost eight years for 1 percent of the oldest women, to suffer a spinal fracture or broken hip. It also took roughly 12 years for 3 percent of the younger women and nearly nine years for 3 percent of the older women without osteoporosis to sustain a spinal fracture or break a hip, wrist, or arm.

The researchers believe that—barring significant health issues—younger with no sign of do not need a repeat bone mineral density test for 10 to 15 years. However, the researchers stressed that who do show signs of are at high risk for a major fracture, and do require regular testing.