Serum ionic fluoride concentrations are significantly decreased after treatment with alendronate in patients with osteoporosis

Abstract

BackgroundWe determined serum ionic fluoride (SIF) concentrations before and after treatment of osteoporosis with alendronate to clarify whether SIF concentrations directly reflect a change in bone metabolism. MethodsA total of 45 postmenopausal women with primary osteoporosis who were treated with alendronate over a 6-month period were enrolled (mean age, 64.2years). SIF concentrations were measured by the flow injection method with an ion-selective electrode. Concentrations of bone turnover markers (serum bone alkaline phosphatase, serum osteocalcin, serum type I collagen cross-linked N-telopeptide and urinary deoxypryridinoline) and lumbar spine BMD (LsBMD) were also measured. SIF, bone turnover markers and LsBMD before and after treatment were compared. ResultsConcentrations of SIF as well as concentrations of all bone turnover markers were significantly decreased after treatment: means (standard deviations) before and after treatment were 0.62 (0.13) and 0.32 (0.09) μmol/l, respectively (P<0.001) and the percent change was −46.3%. LsBMD was also significantly increased by 6.7% after treatment. ConclusionsThe reduction of SIF concentrations is probably caused by inhibition of bone resorption due to the action of alendronate. The findings suggest that SIF concentrations directly reflect a change in bone metabolism.