The bone marker plot: an innovative method to assess bone turnover in women

Abstract

Biochemical markers of bone turnover reflect the resorptive and reconstructive effects that act on the skeleton. Although elevated markers are commonly interpreted as a sign of an increased turnover rate, the balance between bone resorption and formation is mostly neglected. We introduce a graphic report combining both complementary processes. Bone turnover markers were measured in 599 women (aged 25-74 years). To set up reference ranges, 269 from 599 women were selected because of having T-scores > -1 and inconspicuous basic laboratory data. Concentrations of resorption and formation markers were mathematically transformed to build up plots with four fields, symbolizing fast and slow resorption and fast and slow formation processes. The reference data of bone turnover were represented by a 95% confidence ellipse. For individual marker plots, we converted data of bone turnover markers from therapy follow-up profiles of patients in a similar manner. In pre-, peri- and postmenopausal women (n= 190, 39 +/- 6 years; n= 35, 51 +/- 6 years; n= 44, 55 +/- 5 years, respectively), the medians of the bone resorption marker CrossLaps and of the bone formation markers osteocalcin and aminoterminal propeptide of type I procollagen were 0.13/0.16/0.22 ng mL(-1), 21/21/25 ng mL(-1) and 36/35/45 ng mL(-1), respectively. In postmenopausal women, the marker plots revealed a shift towards accelerated bone resorption. A discrimination from osteopenic women (n= 138) failed. The proposed marker plot facilitates the intuitive perception of bone turnover in individual patients as well as in patient groups by a synopsis of the balance between bone formation and resorption with the rate of these processes.