Homocysteine, vitamin B6 and the risk of recurrent venous thromboembolism.

Hyperhomocysteinemia (HHC) is an independent risk factor for cardiovascular disease, and even mildly to moderately elevated homocysteine levels have been associated with a heightened risk for a first and recurrent venous thromboembolism (VTE). Within the frame of a large prospective cohort study (Austrian Study on Recurrent Venous Thromboembolism), we assessed the impact of HHC on the risk of recurrence among 602 patients with a first unprovoked VTE. HHC was an independent risk factor of recurrence conferring a relative risk of 1.5 (95th% CI 1.0-2.4). HHC is caused either by genetic defects and/or by a deficiency of the vitamins (B12, B6 and folic acid) involved in the homocysteine metabolism. Low vitamin B6 levels are associated with an increased risk of a first venous thrombosis. We currently investigate whether or not low plasma levels of PLP are associated with a heightened risk for recurrent VTE.