Vitamin K deficiency and osteopenia in vitamin D-deficient elderly women with Parkinson's disease.

OBJECTIVE

To assess the influence of vitamin K on bone mineral density (BMD) in vitamin-D-deficient women with Parkinson's disease (PD).

DESIGN

Cross-sectional study.

SETTING

Neurology department at a university medical center in Japan.

PARTICIPANTS

Sixty-two women with PD (mean age, 70.7yr) and 62 age-matched controls. Patients were divided into 2 groups according to their functional capabilities: group A (independent: stages I-II of Hoehn and Yahr stages of Parkinson's disease, n = 26); and group B (dependent: Hoehn and Yahr stages 3-5; n = 36).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Sera were analyzed to relate vitamin K concentrations to bone-related biochemical indices. BMD was measured by computed radiograph densitometry.

RESULTS

Group B had significantly lower metacarpal BMD (P <.0001) lower serum concentrations of vitamin K1 (P <.01) and 25-hydroxyvitamin D (25-OHD; P <.0001) than group A. Serum undercarboxylated osteocalcin levels were higher in group B than in group A (P <.0001). The serum concentration of vitamin K1 correlated positively with that of 25-OHD (r =.735, P <.0001), and negatively with undercarboxylated osteocalcin (r = -.751, P <.0001) and Hoehn and Yahr stages (r =.787, P <.0001). Multiple regression analysis identified Hoehn and Yahr stages, vitamin K1, 25-OHD, and undercarboxylated osteocalcin as independent determinants of BMD (P <.0364.0003).

CONCLUSION

In functionally dependent women with PD, nutritional vitamin K1 deficiency is believed to reduce production of fully carboxylated osteocalcin, causing reduced BMD.