Pamidronate and biochemical markers of bone turnover

We have examined the response of different biochemical bone turnover markers to intravenous pamidronate administration (15 mg for 5 days) in 14 patients with Paget's disease, on days 8, 15 and 30 after pamidronate treatment. Urinary parameters of bone resorption, free pyridinolines (Pyr) and hydroxyproline (OHP), as well as serum tartrate-resistant acid phosphatase (TRAP) were measured. Two serum biochemical osteoblastic markers, alkaline phosphatase (AP) and osteocalcin (OC), were also analysed. In addition, ionic calcium (Ca2+) was measured in blood, and parathyroid hormone and calcitriol were measured in serum. All the biochemical markers of bone resorption tested decreased throughout the study. TRAP levels decreased slowly, meanwhile Pyr decreased maximally, below OHP values on day 8. However, the latter were lowest and were lower than those of Pyr on days 15 and 30. AP serum values also decreased during the study. Conversely, OC serum levels increased on days 8 and 15, decreasing to baseline levels on day 30. Ca2+ blood levels decreased while PTH plasma levels increased at all times during the period studied. Calcitriol serum levels increased on day 15. In conclusion, intravenous pamidronate administration was found to modify several biochemical parameters of bone turnover, including Pyr. Moreover, the changes in these parameters were different in intensity and "time course" during the study.