Circulating Dickkopf-1 and sclerostin in patients with Paget's disease of bone.

Paget disease of bone is a chronic metabolic bone disorder characterized by increased bone resorption and new bone formation. The aim of this study is defining the role of inhibitors of canonical Wnt/b-catenin signaling pathway in patients with Paget disease of bone. Scarce and contrasting results have been reported in literature. We studied 40 patients (15 females and 25 males) with radiological and scintigraphic evidence of Paget disease of bone and 40 healthy subjects matched by age and sex. N-propeptide of type I collagen, C-terminal telopeptide of type I collagen, sclerostin, and Dickkopf-related protein 1 (DKK1) were evaluated by blood samples in our laboratory. As expected, mean serum levels of bone turnover markers (N-propeptide of type I collagen and C-terminal telopeptide of type I collagen) were significantly higher in the Paget disease of bone group compared with the control group. No difference was observed between groups in Dickkopf-1 and sclerostin. Dickkopf-1 and sclerostin were never correlated with each other or with bone turnover markers. Sclerostin was positively correlated with age. In conclusion, our results suggest that the regulators of the Wnt-β catenin pathway are not altered in patients with Paget disease of bone. The positive correlation we found between sclerostin and age in Paget disease of bone patients indicates that in comparative studies, sclerostin serum levels must be adjusted for age.