(See also Overview of Thrombotic Disorders Overview of Thrombotic Disorders In healthy people, homeostatic balance exists between procoagulant (clotting) forces and anticoagulant and fibrinolytic forces. Numerous genetic, acquired, and environmental factors can tip... read more .)
Hyperhomocysteinemia may predispose to arterial thrombosis and venous thromboembolism Deep Venous Thrombosis (DVT) Deep venous thrombosis (DVT) is clotting of blood in a deep vein of an extremity (usually calf or thigh) or the pelvis. DVT is the primary cause of pulmonary embolism. DVT results from conditions... read more 
(VTE) by injuring vascular endothelial cells (1 General references Hyperhomocysteinemia may predispose to arterial and venous thrombosis. (See also Overview of Thrombotic Disorders.) Hyperhomocysteinemia may predispose to arterial thrombosis and venous thromboembolism... read more ), possibly due to increased free radical generation. . However, some studies have found that the association is no longer significant when confounding variables are fully accounted for (2 General references Hyperhomocysteinemia may predispose to arterial and venous thrombosis. (See also Overview of Thrombotic Disorders.) Hyperhomocysteinemia may predispose to arterial thrombosis and venous thromboembolism... read more ). Furthermore, randomized trials of vitamin supplementation in patients with VTE and heart disease (3 General references Hyperhomocysteinemia may predispose to arterial and venous thrombosis. (See also Overview of Thrombotic Disorders.) Hyperhomocysteinemia may predispose to arterial thrombosis and venous thromboembolism... read more ) and patients with VTE without major risk factors (4 General references Hyperhomocysteinemia may predispose to arterial and venous thrombosis. (See also Overview of Thrombotic Disorders.) Hyperhomocysteinemia may predispose to arterial thrombosis and venous thromboembolism... read more ) were not associated with reduced event rates. Therefore, routine measurement of homocysteine levels in patients with venous and arterial thromboembolism is discouraged.
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 reductase deficiency. The most common causes of hyperhomocysteinemia are acquired
Folate deficiency Folate Deficiency Folate deficiency is common. It may result from inadequate intake, malabsorption, or use of various drugs. Deficiency causes megaloblastic anemia (indistinguishable from that due to vitamin... read more is rare where folate fortification of wheat flour occurs.
The abnormality is established by measuring fasting plasma homocysteine levels in patients with cardiovascular disease or thromboembolism who are suspected of having the disorder.
General references
1. Undas A, Brozek J, Szczeklik A. Homocysteine and thrombosis: from basic science to clinical evidence. Thromb Haemost 2005;94(5):907-915. doi:10.1160/TH05-05-0313
2. Ospina-Romero M, Cannegieter SC, den Heijer M, Doggen CJM, Rosendaal FR, Lijfering WM. Hyperhomocysteinemia and Risk of First Venous Thrombosis: The Influence of (Unmeasured) Confounding Factors. Am J Epidemiol 2018;187(7):1392-1400. doi:10.1093/aje/kwy004
3. Ray JG, Kearon C, Yi Q, Sheridan P, Lonn E; Heart Outcomes Prevention Evaluation 2 (HOPE-2) Investigators. Homocysteine-lowering therapy and risk for venous thromboembolism: a randomized trial. Ann Intern Med 2007;146(11):761-767. doi:10.7326/0003-4819-146-11-200706050-00157
4. den Heijer M, Willems HP, Blom HJ, et al. Homocysteine lowering by B vitamins and the secondary prevention of deep vein thrombosis and pulmonary embolism: A randomized, placebo-controlled, double-blind trial. Blood 2007;109(1):139-144. doi:10.1182/blood-2006-04-014654
Treatment of Hyperhomocysteinemia
Dietary supplementation
Plasma homocysteine levels may be normalized by dietary supplementation with folate, vitamin B12, or vitamin B6 alone or in combination; however, it is not been shown that this therapy reduces the risk of arterial or venous thrombosis.
Drugs Mentioned In This Article
| Drug Name | Select Trade |
|---|---|
pyridoxine |
B-Natal, Neuro-K-500 |
