Increased Serum 25(OH)D3 Levels in Post-Menopausal Japanese Women with Osteoporosis after 3-Year Bisphosphonate Treatment

Increased Serum 25(OH)D₃ Levels in Post-Menopausal Japanese Women with Osteoporosis after 3-Year Bisphosphonate Treatment

YUKIO NAKAMURA,¹ SHIGEHARU UCHIYAMA,¹ MIKIO KAMIMURA,² SHOTA IKEGAMI,¹ MASATOSHI KOMATSU¹ and HIROYUKI KATO¹

¹Department of Orthopaedic Surgery, Shinshu University, Matsumoto, Nagano, Japan
²Center of Osteoporosis and Spinal Disorders, Kamimura Orthopaedic Clinic, Matsumoto, Nagano, Japan

Osteoporosis is characterized by the systemic impairment of bone mass, strength, and microarchitecture, leading to an increased risk of fragility fracture. Bisphosphonates (BPs) are the first-line drugs for osteoporosis. Vitamin D is considered to be essential for osteoporotic treatment. However, long-term effects of BPs on the serum levels of 25-hydroxyvitamin D₃(25(OH)D₃) are unknown. Accordingly, in this retrospective study, we collected clinical data of 41 post-menopausal Japanese women with osteoporosis treated with BP for over 3 years, without vitamin D supplementation. We measured lumbar and femoral neck bone mineral density (BMD) and serum levels of bone specific alkaline phosphatase (BAP) as a bone formation marker, and tartrate-resistant acid phosphatase (TRACP)-5b as a bone resorption marker, before and after the 3-year treatment. Serum 25(OH)D₃, 1,25(OH)₂D₃, and whole parathyroid hormone (PTH) were also measured. Notably, no fracture occurred during the treatment. Compared with baseline values, 25(OH)D₃ levels were significantly increased from 21.6 to 26.4 ng/mL (P = 0.006), despite no vitamin D supplementation. 1,25(OH)₂D₃ and whole PTH levels tended to be decreased from 62.6 to 57.8 pg/mL and 27.3 to 25.1 pg/mL, respectively. Both bone formation and resorption markers were significantly suppressed (P < 0.01). Both lumbar BMD (7.3% increase) and femoral neck BMD (4.1% increase) were significantly improved (P < 0.0001) after 3 years of the treatment. Thus, even without vitamin D supplementation, serum 25(OH)D₃ levels were significantly increased after 3-year BP therapy. These results suggest that vitamin D supplementation might not be required in the long-term BP therapy for osteoporosis.

keywords —— bisphosphonates; fracture; native vitamin D; osteoporosis; post-menopausal women

===============================

Tohoku J. Exp. Med., 2017, 242, 241-246

Correspondence: Yukio Nakamura, M.D., Ph.D., Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto, Nagano 390-8621, Japan.

e-mail: yxn14@aol.jp

Shigeharu Uchiyama, M.D., Ph.D., Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto, Nagano 390-8621, Japan.

e-mail: sigeuti@shinshu-u.ac.jp