Bone resorption in post-menopausal women with normal and low BMD assessed with biochemical markers specific for telopeptide derived degradation products of collagen type I.

Biochemical markers of bone resorption can be used clinically to predict the risk of osteoporosis-related fractures (prognostic tool) and to assess the response of an osteoporotic patient to an antiresorptive therapy (monitoring tool). Our aim was to assess the ability of four currently marketed biochemical markers of bone resorption, based on the measurement of degradation products from collage type I telopeptides to monitor the elevated resorption associated with menopause. Women (846) were stratified for menopause, age, and bone mineral density and the following markers were measured: urinary cross-linked N-telopeptides of type I collagen (NTx), the levels of breakdown products of type I collagen C-telopeptides in serum (S-CTx), and in urine, by ELISA (U-CTx-E), and RIA (U-CTx-R).

Serum CrossLaps for monitoring the response in individuals undergoing antiresorptive therapy.

The Serum CrossLaps (CTx) enzyme-linked immunosorbent assay (ELISA) is specific for a cross-linked, beta-aspartate-isomerized form of the epitope EKAHDGGR derived from the carboxyterminal telopeptide region of type I collagen alpha(1) chain. Collagen type I fragments reactive in the CTx assay are released during osteoclastic bone resorption and can be used as a measure of bone resorption activity. Our objectives were to assess the intraindividual variation of serum CTx concentration as well as the clinical value of the serum CTx assay for monitoring antiresorptive therapy in individual patients.