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

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 K-2 treatment with or without vitamin D-3. Methods. Thirty-four postmenopausal women with a mean age of 53 years whose bone mineral density (BMD) was less than 0.809 g/cm(2) (osteopenia and osteoporosis) were treated with vitamin K-2 or with a combination of vitamin K2 and vitamin D-3. Seventeen women received daily oral administration of 45 mg vitamin K-2 and 17 women received daily oral administration of 45 mg vitamin K-2 plus 0.75 mu g 1 alpha-hydroxyvitamin D-3. 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 I and 2 years after the start of treatment. Results. Serum uc OC levels in women treated with vitamin K-2 alone and with both vitamin K-2 and vitamin D3 decreased significantly (p < 0.05). Serum levels of intact OC and BAP in women treated with vitamin K-2 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 K-2 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 1,,2 decreased due to carboxylation of uc OC. Combined treatment with vitamin K-2 and vitamin D-3 may be effective for sustaining BMD in early postmenopausal women whose bone turnovers are highly activated.