VARIABLE EFFICACY OF BONE REMODELING BIOCHEMICAL MARKERS IN THE MANAGEMENT OF PATIENTS WITH PAGETS-DISEASE OF BONE TREATED WITH TILUDRONATE

The aim of this work was to evaluate the response of different biochem ical bone markers to tiludronate administration in Paget's disease of bone. Ten patients (five men and five women), 56-77 years old (67 +/- 6.5), were treated for 3 months with tiludronate tablets (400 mg/day). Bone formation markers: alkaline phosphatase (AP), bone alkaline phos phatase (bAP), osteocalcin (BGP), and procollagen I carboxyterminal pr opeptide (PICP) in serum; and bone resorption markers: serum cross-lin ked carboxyterminal telopeptides of type I collagen (ICTP), urinary hy droxy proline/creatinine (Hyp/Cr), pyridinoline/Cr (Pyr/Cr), and alpha -1 collagen chain products degradation (CrossLaps) were assessed. Samp les were taken before and at monthly intervals for 3 months after trea tment began. The results of the present work show that serum AP and bA P are sensitive and reliable biochemical markers of bone formation in the follow-up of tiludronate in this disease. Serum PICP shows less se nsitivity than serum AP, and serum BGP is not indicated as biochemical marker in these types of studies. Urinary hydroxyproline seems to be the most reliable biochemical marker of bone resorption. More studies should be performed with urinary Pyr and CrossLaps determinations. Ser um ICTP is not adequate for the follow-up of tiludronate treatment in Paget's disease of bone.