Effect of vitamin K₂ treatment on carboxylation of osteocalcin in early postmenopausal women

Abstract

Objective. We examined the serum level of undercarboxylated osteocalcin (uc OC), which is a sensitive marker of vitamin K status, and levels of bone turnover markers in early postmenopausal women receiving vitamin K₂ treatment with or without vitamin D₃.

Methods. Thirty-four postmenopausal women with a mean age of 53 years whose bone mineral density (BMD) was less than 0.809 g/cm² (osteopenia and osteoporosis) were treated with vitamin K₂ or with a combination of vitamin K₂ and vitamin D₃. Seventeen women received daily oral administration of 45 mg vitamin K₂ and 17 women received daily oral administration of 45 mg vitamin K₂ plus 0.75 µg 1α-hydroxyvitamin D₃. Serum levels of uc OC, intact osteocalcin (OC) and bone alkaline phosphatase (BAP), urinary deoxypyridinoline (DPD) levels and BMD at the lumbar spine were measured before and at 1 and 2 years after the start of treatment.

Results. Serum uc OC levels in women treated with vitamin K₂ alone and with both vitamin K₂ and vitamin D₃ decreased significantly (p < 0.05). Serum levels of intact OC and BAP in women treated with vitamin K₂ did not show significant changes, while those in women who received the combined treatment decreased significantly (p < 0.05). On the other hand, urinary DPD level in women treated with vitamin K₂ did not change, while that in women who received the combined treatment tended to decrease (p < 0.1).

Conclusion. Serum uc OC levels in early postmenopausal women who received vitamin K₂ decreased due to carboxylation of uc OC. Combined treatment with vitamin K₂ and vitamin D₃ may be effective for sustaining BMD in early postmenopausal women whose bone turnovers are highly activated.

Keywords:

• Vitamin K
• bone health
• undercarboxylated osteocalcin
• early postmenopause