Merck Manual

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Hyperhomocysteinemia

By

Michael B. Streiff

, MD, Johns Hopkins University School of Medicine

Reviewed/Revised Aug 2023
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Hyperhomocysteinemia may predispose to arterial and venous thrombosis.

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 Deep Venous Thrombosis (DVT) (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

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

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
B-Natal, Neuro-K-500
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NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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