Urinary excretion of type I collagen cross-linked N-telopeptides, bone mass and related lifestyle in middle-aged women

The relationship between past and present lifestyle and urinary excretion o f type I collagen cross-linked N-telopeptides (NTx) was studied in 61 Japan ese females aged 34-59, with a view toward using NTx excretion rates as a p redictor of future osteoporosis. Bone mineral density (BMD) of the lumbar s pine, the speed of sound (SOS) and broadband ultrasound attenuation (BUA) o f the os calcis, urinary NTx, serum osteocalcin (BGP) and bone-specific alk aline phosphatase (BAP) were measured. Stiffness index (stiffness) was calc ulated from SOS and BUA. The subjects were asked whether they took regular exercise in their childhood and teen years (in elementary, junior-high, sen ior-high school and college), the past (20-40 years of age) and present adu lthood. Regular calcium intake, smoking habits, alcohol and other beverage consumption and milk consumption were also covered in the questionnaire. Th e mean NTx values of premenopausal and postmenopausal group were 22.2 and 5 6.0 nM bone collagen equivalents (BCE)/mM urinary creatinine (Cr), respecti vely. The group which did not exercise regularly between the ages of 20 and 40 had a higher mean NTx value (40.9 nMBCE/mMCr) than the group which did exercise regularly (22.7 nMBCE/mMCr). In multiple regression analyses, age, stiffness and exercise in past adulthood could explain 43.5% of the NTx va riance. For prevention of bone metabolic increases around menopause, habitu al exercise in early adulthood seems to be effective.