Markers of bone resorption in patients treated with pamidronate

Pyridinoline (PYD), deoxypyridinoline (DPD), and N-telopeptide (NTX) are ma rkers of bone resorption. In cancer patients with bone metastases, NTX is m ore often elevated than either of the pyridinolines. Bisphosphonates inhibi t osteoclasts and their treatment decreases skeletal complications of malig nancy. The aim of this study was to correlate urinary PYD, DPD, and NTX lev els with clinical events in patients receiving pamidronate. 25 cancer patie nts with lytic bone disease were treated with monthly pamidronate combined with endocrine or chemotherapy; 27 others were on placebo. Twenty-four hour urines were collected at baseline, 1, 3 and 6 months. NTX values were dete rmined by enzyme-linked immunosorbent assay (ELISA); PYD and DPD values wer e determined by reverse phase high performance liquid chromatography (HPLC) . Two hour urines were also collected weekly for 21 patients. The greatest difference as a result of pamidronate treatment was observed in NTX values. Maximum suppression was achieved 2 weeks after treatment. Of the 25 patien ts who received pamidronate, 21 had initially elevated NTX values. 12 of th e 21 finished with normal NTX values, whilst 9/21 had NTX values which rema ined abnormally elevated. The proportions of patients with fractures betwee n these two subgroups approached statistical significance (P= 0.07) while t he proportions with bony disease progression were significant (P= 0.03, Fis her's exact test). Measuring NTX levels appears useful in monitoring bispho sphonate therapy of bone metastases. The goal of treatment should be to nor malise NTX excretion. (C) 1998 Elsevier Science Ltd. All rights reserved.