Long Term Effects on Biochemical Bone Markers of a Single Infusion of Zoledronic Acid in Paget Disease of Bone

Background: The aim of the present study is to evaluate long term biochemical response to a single dose of zoledronic acid in patients with Paget disease of bone, as well as evaluating the value of bone turnover markers in diagnosis and follow-up. Methods: This is an observational, descriptive and prospective study. Included patients received a single-dose intravenous infusion of 5 mg zoledronic acid. Bone turnover markers were measured at baseline, and in every follow up visit. Results: Thirty-nine patients with a mean follow-up of 56.49 months were included. At the time Paget disease was diagnosed, all of the patients (100%) had high serum procollagen type 1 amino-terminal propeptide values, but not all patients had high serum C-terminal telopeptide and alkaline phosphatase values (85% and 89% respectively). Biochemical response to therapy occurred in 38 out of 39 patients (97%). Two patients had partial response at 6 months but complete response thereafter. Only one patient relapsed (nadir procollagen type 1 amino-terminal propeptide 35.06 mg/l, value at relapse 75.2 mu g/l) 4.5 years after treatment. Values of serum C-terminal telopeptide and alkaline phosphatase of this patient were normal despite P1NP relapse. Conclusions: We hence conclude that zoledronic acid is effective in inducing and maintaining biochemical remission and that procollagen type 1 amino-terminal propeptide is a better diagnostic and prognostic marker in PDB when compared to C-terminal telopeptide and alkaline phosphatase. (C) 2019 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.