Factors affecting bone loss around menopause in women without HRT: a prospective study.

OBJECTIVES The present study evaluated the effects of menopause and other putative bone loss modifying factors on bone mineral density (BMD) change. METHODS The study population, 396 healthy women aged 48-59 years with no history of hormone replacement therapy (HRT) use or any bone affecting disease or medications, was selected from a random sample (n=2025) of the OSTPRE-study cohort (n=13100) in Kuopio, Finland. BMD at lumbar spine (LS) and three areas of proximal femur (femoral neck (FN), Ward's triangle (W), trochanter (T)) was measured with dual X-ray absorptiometry at baseline in 1989-1991 and at 5 years in 1994-1997. RESULTS 116 women who reported the beginning of menopause during the follow-up (perimenopausal) had the greatest mean annual bone loss (-1.22%/year (LS), -0.87% year (FN), -1.14%/year (W), -0.36%/year (T)). In women under 5 years postmenopausal at baseline (early postmenopausal, n=172) bone loss rate was significantly lower than in perimenopausal women. In women over 5 years postmenopausal at baseline (late postmenopausal, n=108) bone loss rate was significantly further decreased only at lumbar spine. In peri- and postmenopausal women the annual BMD change was best described as a trinomial function of the duration of menopause at all sites (P<0.03). Of the life-style factors studied protective effects were found in weight increase in both spinal and femoral bone (P=0.010/P<0.001), high baseline weight in spine (P<0.001) and high grip strength in femoral neck (P=0.002). CONCLUSION The beginning of menopause is accompanied by significant bone loss, which decreases in later menopause. Few other physiological and life-style factors were found to significantly contribute to this phenomenon.