Changes in vitamin D metabolites during teriparatide treatment

摘要

Parathyroid hormone (PTH) increases the conversion of 25-hydroxyvitamin D [25(OH)D] to 1,25 dihydroxyvitamin D [1,25(OH) 2D]. The purpose of this study was to assess the changes in serum concentration of vitamin D metabolites 1,25 dihydroxyvitamin D [1,25(OH) 2D] and 25-hydroxyvitamin D [25(OH)D] during teriparatide 20μg/day (teriparatide) therapy in the double-blind Fracture Prevention Trial of postmenopausal women with osteoporosis and in the male study of men with osteoporosis. Patients were randomized to teriparatide or placebo and received daily supplements of calcium 1000mg and vitamin D 400-1200IU. Serum concentrations of 1,25(OH) 2D and 25(OH)D were measured. In women (N=336), median 1,25(OH) 2D concentrations at 1month increased from baseline by 27% (P0.0001) in the teriparatide group versus -3% (P=0.87) in the placebo group (between group P0.0001). At 12months, the increase was 19% (P0.0001) in the teriparatide group versus -2% (P=0.23) in the placebo group (P0.0001). Median 25(OH)D concentrations at 12months decreased by 19% (P0.0001) in the teriparatide group versus 0% (P=0.13) in the placebo group (P0.0001). In men (N=287), median 1,25(OH) 2D concentrations at 1month increased by 22% (P0.0001) in the teriparatide group versus 0% (P=0.99) in the placebo group (P0.0001). At 12months, the increase was 14% (P0.0001) in the teriparatide group versus 5% (P=0.004) in the placebo group (P=0.17). Median 25(OH)D concentrations at 12months decreased by 11% (P=0.001) in the teriparatide group versus an increase of 1% (P=0.20) in the placebo group (P=0.003). Therefore, treatment with teriparatide increases 1,25(OH) 2D concentrations and decreases 25(OH)D concentrations.