Homocysteine

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Serum Homocysteine [Hcy]

Introduction:

Total Homocysteine (HCy) has been added to the list of tests performed at this facility. The lab uses an immunoassay to measure the amount of total L-homocysteine. The assay measures all forms of L-homocysteine including homocystine, and thiol- and protein-bound HCy.

Reference Range: Desirable <11 m mol/L; Hyper elevated > 15 m mol/L.

Specimen Requirements:

Specimen: Serum

Collection Container: SST tube

Collection Volume: 3.0 mL blood (1.0 mL minimum)

Aliquot: 0.5 mL serum (0.5 mL minimum)

Processing Instructions: Separate serum from cells immediately; store refrigerated (2 weeks) or frozen (-20^oC) (6 months); label as a fasting Homocysteine with patient identifiers including time and date of collection. When shipping from outside source freeze specimen and ship on ice-pack overnight to lab.

Complete requisition: Indicate "Fasting Homocysteine." Complete all Medicare information as required.

Turn-around-time: two working days after receipt of specimen

CPT Code: 82130

Charge: $ 50 plus shipping

Clinical Factors: Uses include the evaluation of the risk of cardiovascular disease and the diagnosis and treatment of patients suspected of having hyperhomocysteinemia and homocystinuria.

A. Factors which can result in increased SERUM Homocysteine:

Genetics: altered enzyme activity of HCy related pathways

Sex: men higher than women

Diet: low intake of B₆, B₁₂, Folate, and/or methionine

Renal (kidney) disease: increases with serum creatinine

Transplantation

Post stroke

Severe psoriasis

Corticosteroid therapy

Cyclosporine

Smoking

B. Diseases associated with increased SERUM Homocysteine:

Atherosclerosis and other vascular diseases

Neural Tube Defects

C. Risk for Atherosclerosis is due to increased Homocysteine is:

Independent of cholesterol and other lipid evaluations
Approximately equal to cigarette smoking in magnitude
Increases risk from other risk factors (i.e. hypertension, smoking, hypercholesterolemia) in both men and women

Other risk factor analyses can also be determined, see the other analyte section for more details.

D. Therapy for increased SERUM Homocysteine:

Increased intake of Folate, B₆, and/or B₁₂ by diet or supplementation or both.

References:

Boers, G.H.J., Hyperhomocysteinemia as a risk Factor for Arterial and Venous Disease. A Review of Evidence and Relevance, Thrombosis and Haemostasis 78:520-522(1997).
Graham, I.M. et al., Plasma Homocysteine as a Risk Factor for Vascular Disease The European Concerted Action Project, J. Amer. Med. Assoc. 277:1775-1781(1997).
Jing, M. et al., Methenetetrahydrofolate Reductase Polymorphism, Plasma Folate, Homocysteine, and Risk of Myocardial Infarction in US Physicians, Circulation 94:2410-2416(1996).
Malinow, M.R., Plasma Homocyst(e)ine and Arterial Occlusive Diseases: A Mini-Review, Clin. Chem. 40:173-176(1994).
Mayer, E.L. et al., Homocysteine and Coronary Atherosclerosis, J. Am. Coll, Cardiol. 27: 517-27(1996).
Miner, S.E.S., et al., Clinical Chemistry and Molecular Biology of Homocysteine Metabolism: An Update. Clin. Biochem. 30:189-197(1997)
Omenn, G.S., et al., Preventing Coronary Heart Disease: B Vitamins and Homocysteine, Circulation 97:421-424 (1998).
Nygard, O. et al., Plasma Homocysteine Levels and Mortality in Patients with Coronary Artery Disease, New Engl. J. Med. 337:230-236(1997).
Verhoef, P., et al., Plasma Total Homocysteine and Risk of Angina Pectoris with Subsequent Coronary Artery Bypass Surgery, Amer. J. Cardiol. 79:799-801(1997).
Verhoef, P., et al., Plasma Total Homocysteine, B Vitamins, and Risk of Coronary Atherosclerosis, Arter. Thromb. Vasc. Biol. 17:989-995(1997).

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Last modified: December 03, 1998