Aim: Urinary C-terminal telopeptide of type I collagen (u-CTx) has been reported to be a sensitive biochemical marker of bone turnover. There have been two assays for urinary CTx, which are u-aCTx and u-BCTx. A newly developed immunoassay for serum CTx (s-CTx) is now available for assessment of bone resorption. We have both evaluated the effects of menopause, and osteoporosis on the measurements of serum CTx and compared them to urinary CTx assays.

Subjects: 79 premenopausal healthy women, 80 post-menopausal healthy women, 61 osteoporotic patients with vertebral fractures and 34 osteoporotic patients with hip fractures

Results: Bone resorption markers were increased after menopause. There was no significant difference among s-CTx, u-aCTx and u-BCTx in the T-scores of post-menopausal group over premenopausal group (T -score; s-CTx:2.3, u-aCTx:1.8, u-BCTx:2.1). Patients with vertebral fractures and patients with hip fracture had elevated levels of bone resorption markers compared to age-matched healthy postmenopousal women. There was no significant difference among s-CTx, u-aCTx and u-BCTx in the T-scores against postmenopausal group in vertebral fracture group (T -score; s-CTx:0.8, u-aCTx:0.9, u-BCTx:0.7) and in hip fracture group women (T-score; s-CTx:1.1, u-aCTx: 1.3 u-BCTx: 1.3).

Conclusions: These findings indicate that s-CTx reflects the increase of bone resorption associated with menopause and osteoporosis with vertebral fractures and hip fractures.