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It is unclear if identifying individuals with hyperhomocysteinemia in the evaluation of venous thromboembolism is clinically relevant, because interventions for decreasing homocysteine level in such individuals do not reduce their risk of first or recurrent VTE. Therefore, testing for hyperhomocysteinemia and MTHFR mutations in patients with VTE is not recommended. The clinical relevance of measuring homocysteine levels is also unclear when evaluating risk of atherosclerotic events. Homocysteine-lowering therapy has not been shown to reduce the risk of myocardial infarction or total cardiovascular death in clinical trials. Testing for MTHFR mutations is not recommended. B vitamin supplementation (folic acid, vitamin B6, and vitamin B12, either alone or in some combination) may lower homocysteine levels within a few weeks. However, clinical trials have not demonstrated that decreasing the levels of homocysteine reduces recurrent VTE, even in patients with high baseline levels. Based on currently available data, treating hyperhomocysteinemia in patients with VTE is not recommended.
B vitamin supplementation for primary prevention of cardiovascular disease is also not recommended in areas where there is prevalent folate-fortification of grains. In regions where folate-fortification of grains is uncommon, vitamin supplementation can be considered in those patients with other atherosclerotic risk factors with the aim of reducing risk of stroke.