Homocysteine enzymatic

In vitro test for the quantitative determination of total L homocysteine in human serum and plasma on cobas c systems.

Homocysteine enzymatic

In vitro test for the quantitative determination of total L homocysteine in human serum and plasma on cobas c systems.

 

The assay can assist in the diagnosis of patients suspected of having hyperhomocysteinemia or homocystinuria.

Homocysteine (Hcy) is a thiol containing amino acid produced by the intracellular demethylation of methionine. Total homocysteine (tHcy) represents the sum of all forms of Hcy including forms of oxidized, protein bound and free.

Elevated levels of tHcy has emerged as an important risk factor in the assessment of cardiovascular disease.1,2,3 Excess Hcy in the blood stream may cause injuries to arterial vessels due to its irritant nature, and result in inflammation and plaque formation, which may eventually cause blockage of blood flow to the heart. Elevated tHcy levels are caused by four major factors, including:

  1. Genetic deficiencies in enzymes involved in Hcy metabolism such as cystathionine beta synthase (CBS), methionine synthase (MS), and methylenetetrahydrofolate reductase (MTHFR)
  2. Nutritional deficiency in B vitamins such as B6, B12 and folate
  3. Renal failure for effective amino acid clearance
  4. Drug interactions, such as with nitric oxide, methotrexate and phenytoin that interfere with Hcy metabolism. Elevated levels of tHcy are also linked with Alzheimer’s disease4, neuropsychiatric diseases5 and Osteoporosis.6 Guidelines for tHcy determination in clinical laboratories have been established.7,8
Homocysteine enzymatic
  1. Eikelboom JW, Lonn E, Genest J Jr, et al. Homocyst(e)ine and cardiovascular disease: A critical review of the epidemiologic evidence. Ann Intern Med 1999;131(5):363-375. 
  2. Scott J, Weir D. Homocysteine and cardiovascular disease. Q J Med 1996;89(8):561-563. 
  3. Nygard O, Nordrehaug JE, Refsum H, et al. Plasma homocysteine levels and mortality in patients with coronary artery disease. N Engl J Med 1997;337(4):230-236.
  4. Seshadri S, Beiser A, Selhub J, et al. Plasma homocysteine as a risk factor for dementia and Alzheimer's disease. N Engl J Med 2002;346(7):476-483.
  5. Stanger O, Fowler B, Piertzik K, et al. Homocysteine, folate and vitamin B12 in neuropsychiatric diseases: review and treatment recommendations. Expert Rev Neurother 2009;9(9):1393-1412.
  6. McLean RR, Jacques PF, Selhub J, et al. Homocysteine as a predictive factor for hip fracture in older persons. N Engl J Med 2004;350(20):2042-2049.
  7. Refsum H. Total Homocysteine: Guidelines for Determination in the Clinical Laboratory. Clin Lab News 2002 May;12-14 (www.aacc.org).
  8. Refsum H, Smith AD, Ueland PM, et al. Facts and Recommendations about Total Homocysteine Determinations: An Expert Opinion. Clin Chem 2004;50(1):3-32.