(See also Overview of Thrombotic Disorders.)
Hyperhomocysteinemia may predispose to arterial thrombosis and venous thromboembolism by injuring vascular endothelial cells. Some experts believe, however, that there is insufficient evidence to link hyperhomocysteinemia to thrombosis definitively.
Plasma homocysteine levels are elevated ≥ 10-fold in homozygous cystathionine beta-synthase deficiency. Milder elevations occur in heterozygous deficiency and in other abnormalities of folate metabolism, including methyltetrahydrofolate dehydrogenase deficiency. The most common causes of hyperhomocysteinemia are acquired
Folate deficiency is rare in the Western world due to folate fortification of wheat flour.
The abnormality is established by measuring plasma homocysteine levels in patients with cardiovascular disease or thromboembolism who are suspected of having the disorder.