Hyperhomocysteinemia may predispose to arterial and venous thrombosis through unclear mechanisms.
Hyperhomocysteinemia may predispose to arterial thrombosis and venous thromboembolism, possibly because of injury to vascular endothelial cells. Plasma homocysteine levels are elevated ≥ 10-fold in homozygous cystathionine β-synthase deficiency. Milder elevations occur in heterozygous deficiency and in other abnormalities of folate metabolism, including methyltetrahydrofolate dehydrogenase deficiency. However, by far the most common causes of hyperhomocysteinemia are acquired deficiencies of folate, vitamin B12, or vitamin B6 (pyridoxine).
The diagnosis is established by measuring plasma homocysteine levels.
Plasma homocysteine levels may be normalized by dietary supplementation with folate, vitamin B12, or vitamin B6 alone or in combination; however, it is not clear that this therapy reduces the risk of arterial or venous thrombosis.
Last full review/revision January 2013 by Joel L. Moake, MD
Content last modified November 2013