Effect of oral anticoagulant treatment on markers for calcium and bone metabolism

Vitamin K-dependent proteins regulate blood coagulation as well as bone gro wth and calcification. Here, we have compared the effects of oral anticoagu lants on circulating vitamin K-dependent proteins and on markers for calciu m and bone metabolism. Patients with a clinical indication for antithrombot ic therapy were randomized into three groups and treated with either aspiri n, regular-intensity anticoagulation [target international normalized ratio (INR) values: 2.5-3.5] or low-intensity anticoagulation (target INR values : 1.1-1.6). At the start and after 1 year of treatment, various biochemical markers were assessed. Both the circulating levels and the degree of carbo xylation of the various gamma -carboxyglutamate (Gla)-containing proteins w ere affected differently by oral anticoagulant treatment. Circulating osteo calcin was more sensitive to poor vitamin K status than other Gla proteins. From the fact that - except for osteocal cin - neither markers for osteobl ast nor osteoclast function were affected by oral anticoagulant treatment, we conclude that bone turnover remained unaltered, which is indicative of a n unchanged rate of bone loss. Whether the long-term production of undercar boxylated bone Gla proteins may have a negative effect on the quality of bo ne (e.g. bone strength) cannot be concluded from this study. Copyright (C) 2001 S.Karger AG, Basel.