Correlations between biochemical markers of bone turnover and bone density responses in patients with glucocorticoid-induced osteoporosis treated with teriparatide or alendronate.

The purpose of this post hoc analysis was to determine whether baseline concentrations or early changes in serum bone turnover markers were correlated with changes in bone mineral density (BMD) at 18 months in patients with glucocorticoid-induced osteoporosis (GIO) treated with teriparatide (n=80; 20 mug/day) or alendronate (n=77; 10 mg/day). Bone markers included type I collagen N-terminal propeptide (PINP), type I collagen C-terminal propeptide (PICP), bone alkaline phosphatase (bone ALP), and cross-linked C-telopeptide of type I collagen (Sbeta-CTX). The relationship between baseline and early changes in markers and the 18-month changes in lumbar spine (LS) and femoral neck (FN) BMD was evaluated using Spearman correlation analysis. In the teriparatide group, increases in LS and FN BMD at 18 months were not significantly correlated with baseline marker concentrations (P>0.05) but were correlated with the increases in PINP at 1 and 6 months (P<0.05). In the alendronate group, the increase in FN BMD at 18 months was positively correlated with baseline marker concentrations (P<0.05) and negatively correlated with change in PINP and Sbeta-CTX at 1 and 6 months. In addition, in the alendronate group, the increase in LS BMD was negatively correlated with change in Sbeta-CTX at 1 month (P<0.05). Increases in BMD at the spine and hip were independent of baseline bone turnover in the teriparatide group, while increases in hip BMD were dependent on baseline bone turnover in the alendronate group. With both therapies, early changes in some bone turnover markers were correlated with 18-month gains in BMD in patients with GIO.