BIOCHEMICAL MARKERS OF BONE TURNOVER REFLECT FEMORAL BONE LOSS IN ELDERLY WOMEN

Although over 90% of hip fractures occur in patients over age 70, few data are available on femoral bone loss in this age group. To examine the relationship between biochemical markers of bone turnover and femo ral bone los in the elderly, 36 female and 17 male, healthy, community -dwelling elderly over age 65 (mean +/- SD age: women 71 +/- 4 years, men 75 +/- 5 years) were followed for 3 years. Annual bone mineral den sity measurements of the hip and lumbar spine by dual-energy x-ray abs orptiometry (DXA) were obtained and biochemical marker of bone resorpt ion (urinary N-telopeptide crosslinks, free pyridinoline, total pyridi noline, total deoxypyridinoline, and hydroxyproline) and bone formatio n (serum osteocalcin, bone-specific alkaline phosphatase) were obtaine d at the end of year 3. In elderly women, longitudinal bone loss at th e total hip was negatively correlated with markers of bone resorption (r = -0.39 to -0.52. P<0.05), bone formation ( r = -0.38, P<0.05), and age (r = -0.39, P<0.05). Markers of bone resorption were correlated w ith markers of bone formation (r = 0.63 to 0.74 P<0.01). In multiple r egression analysis, urinary N-telopeptide crosslinks (marker of resorp tion), serum osteocalcin (marker of formation), and serum parathyroid hormone explained 43% of the variability of bone loss at the total hip in women. These parameters were not related to bone loss in men. We c onclude that femoral bone loss increases with age in women over 65. Me asurements of specific biochemical markers of bone turnover are correl ated with longitudinal bone los in elderly women. These markers may he lp identify women at greatest risk for bone loss who would benefit mos t from therapeutic interventions.