Serum homocysteine levels are affected by renal function during a 3-year period of minodronate therapy in female osteoporotic patients

Serum homocysteine is a possible marker to indicate bone quality. However, it is not clear whether changes are seen in serum homocysteine levels with long-term bisphosphonate therapy. We aimed to investigate the factors affecting serum homocysteine levels during a 3-year period of monthly minodronate therapy in osteoporotic women, and to examine if the serum homocysteine levels could reflect some aspects of bone metabolism. The study included 43 patients (age 72.3 ± 7.0 years) undergoing treatment for osteoporosis for the first time (New group) and 35 patients (age 74.4 ± 8.2 years) who switched from alendronate or risedronate to minodronate (Switch group). Minodronate (50 mg/every 4 weeks) was administered for 36 months. Lumbar, femoral neck, and total hip bone mineral densities (BMD), and serum homocysteine levels were monitored at baseline and after 9, 18, 27, and 36 months of treatment. Lumbar BMD increased significantly in both groups (New group 11.4%, Switch group 6.2%). However, femoral neck and total hip BMDs increased only in the New group (femoral neck 3.6%, total hip 4.1%). Serum homocysteine levels increased significantly at 18 and 27 months in all subjects. Multiple linear regression analysis revealed that changes in homocysteine levels during 18, 27, and 36 months significantly correlated with changes in creatinine clearance during the same corresponding periods (18 months: B = − 0.472, p = 0.003; 27 months: B = − 0.375, p = 0.021; 36 months: B = − 0.445, p = 0.012). Thus, serum homocysteine levels possibly reflect renal function instead of bone metabolism during minodronate therapy.