Changes in serum levels of biochemical markers of bone turnover during 10 years among Japanese men and women: associated factors and birth-cohort effect. The Taiji Study

We aimed to clarify changes in biochemical markers of bone turnover (BTMs) over 10 years, associations with changes in bone mineral density (BMD), and birth-cohort effects in a Japanese community. We randomly selected 400 individuals (age, 40-79 years; 50 of each gender and age stratum) from a list of registered residents in 1993. We measured BMD of the spine and hip, and serum concentrations of total osteocalcin (OC), beta-C-terminal cross-linking telopeptide of type I collagen (beta-CTX), and N-terminal cross-linking telopeptide of type I collagen (NTX), in 1993 and 2003. Of the 400 subjects, 322 (153 men, 169 women) completed the 10-year follow-up. Mean change rates (standard deviation) for serum total OC, beta-CTX, and NTX over 10 years were -1.00 (3.74)%/year, 5.10 (22.48)%/year, and 0.40 (3.41)%/year, respectively, in men, and 0.02 (5.32)%/year, 5.53 (14.54)%/year, and 0.62 (3.26)%/year, respectively, in women. Change rates of BTMs were higher for women in their forties than for women in their fifties to seventies (P < 0.05), and higher in the menstrual transition group than in pre- and postmenopausal groups (P < 0.001). Changes in levels of BTMs over 10 years in women were significantly associated with change rates of BMDs at L2-L4 and total hip after adjusting for potential confounders. A significant birth-cohort effect was observed among women in their fifties. We concluded that change rates of BTMs during the 10 years were influenced by menstrual transition, age, and sex and associated with bone loss at L2-L4 and total hip.