Reduced axial bone mineral content in patients taking an oral anticoagulant.

Recent literature indicates that the vitamin K cycle plays a role in the calcification process, presumably via its intervention on gamma-carboxylation of the noncollagenous proteins of bone osteocalcin and matrix gamma-carboxyglutamic acid protein. The major clinical evidence of this interference is fetal bone defect caused by oral anticoagulants given to the mother during the first trimester of pregnancy. No bone abnormalities have been reported so far in adults receiving oral anticoagulants. We studied 56 women who had had cardiac valve replacement and who were given acenocoumarol as anticoagulant, and 61 age-matched women who were in the same New York Heart Association functional class but who were not taking anticoagulants. Osteocalcin serum levels were comparable between the two groups; bone density values measured at appendicular bone were significantly lower in patients taking acenocoumarol. No significant correlation was found between duration of treatment and bone density. Significant osteopenia was present in the women being treated with oral anticoagulants.