Short-term bisphosphonate treatment reduces serum 25(OH) vitamin D and alters values of parathyroid hormone, pentosidine, and bone metabolic markers.

This study aimed to clarify the effects of short-term bisphosphonate (BP) administration in Japanese osteoporotic patients retrospectively. Daily minodronate (MIN) at 1 mg/day (MIN group) or weekly risedronate (RIS) at 17.5 mg/week (RIS group) was primarily prescribed for each patient. We analyzed the laboratory data of 35 cases (18 of MIN and 17 of RIS) before the start of treatment and at 4 months afterward. The changes in 25(OH)D, whole parathyroid hormone (PTH), serum pentosidine, and the bone turnover markers urinary cross-linked N-telopeptide of type I collagen (NTX), serum tartrate-resistant acid phosphatase (TRACP)-5b, bone-specific alkaline phosphatase (BAP), and undercarboxylated osteocalcin were evaluated. Overall, serum 25(OH)D was significantly decreased from 21.8 to 18.4 ng/mL at 4 months, with a percent change of -14.7%. Whole PTH increased significantly from 23.4 to 30.0 pg/mL, with a percent change of 32.1%. Serum pentosidine rose from 0.0306 to 0.0337 μg/mL, with a percent change of 15.2%. In group comparisons, 25(OH)D and pentosidine showed comparable changes in both groups after 4 months of treatment, whereas whole PTH became significantly more increased in the MIN group. All bone turnover markers were significantly decreased at 4 months in both groups. Compared with the RIS group, the MIN group exhibited significantly larger value changes for urinary NTX, serum TRACP-5b, and BAP at the study end point. This study demonstrated that serum 25(OH)D became significantly decreased after only 4 months of BP treatment in Japanese osteoporotic patients and confirmed that MIN more strongly inhibited bone turnover as compared with RIS.