Vitamin K deficiency and osteopenia in disuse-affected limbs of vitamin D-deficient elderly stroke patients.

Bone mineral density is reduced in stroke patients on the hemiplegic and contralateral sides, reflecting a degree of paralysis and vitamin D deficiency. Because the deficiency of vitamin K, a factor essential for site-specific carboxylation of bone Gla protein, is also associated with reduced bone mineral density, an additional contribution of vitamin K to bone changes was assessed in 168 elderly patients with long-standing post-stroke hemiplegia and hypovitaminosis D. Sera were analyzed to relate vitamin K1 concentrations to bone-related biochemical indexes and bone mineral density measured by radiodensitometry of the second metacarpal. Bone mineral density was lower on both sides in patients than in the 56 controls (P < 0.02). Serum vitamin K1 concentrations, which correlated positively with bone Gla protein concentrations (P < 0.0001), were lower in patients (0.48 +/- 0.47 nmol/L) than controls (1.33 +/- 0.49; P < 0.0001). Serum bone Gla protein and 25-hydroxyvitamin D concentrations were lower in patients than controls (P < 0.0001), whereas ionized Ca concentrations were higher in patients (1.277 +/- 0.041 mmol/L) than controls (1.210 +/- 0.049; P < 0.0001), correlating with the Barthel index. Multivariate linear regression identified vitamin K1, bone Gla protein, 25-hydroxyvitamin D, ionized calcium, and the Barthel index as independent bone mineral density determinants on the hemiplegic side and 25-hydroxyvitamin D, calcium, and the Barthel index on the intact side. Immobilization and vitamin K deficiency had stronger osteopenic effects on the hemiplegic side than contralaterally.