Homocysteine (HCY)

Hyperhomocysteinemia is a medical condition characterized by elevated levels of the intermediate amino acid, homocysteine (HCY), in the blood.1 HCY plays a key role in the remethylation/transmethylation and transsulfuration pathways that require folate, cobalamin, and pyridoxine as cofactors. Hence, any genetic defect in the enzymes that mediate HCY metabolism or deficiency of the cofactors can lead to the blood disorder.

Determinants and Factors Associated with Hyperhomocysteinemia

Genetic Defects Disease Drugs Lifestyle Factors
MTHFR-polymorphism (frequent) B-vitamin deficiency
(folate, B12, B6, B2)
Anti-epileptics Low exercise
CBS-deficiency (rare) Impaired renal function Methotrexate Smoking
inflammatory bowel disease
Omeprazole High alcohol consumption
  Diabetes Theophylline High coffee consumption
  Hypothyroidism Metformin Poor nutrition

Clinical Applications

An elevated HCY level is considered to be an independent risk factor for:

  • Cardiovascular diseases (CVD)
  • Atherosclerosis and thrombosis
  • Stroke
  • Peripheral vascular disease
  • Dementia-type disorders
  • Osteoporosis-associated fractures2,3,4,5,6,7

Reduction in HCY levels by 3 μmol/L from the existing levels lowers the risk of:

  • Ischemic heart disease by 16%
  • Deep venous thrombosis by 25%
  • Stroke by 24%

Interpretation of HCY Levels2

In the general population, the normal levels of HCY range between 5 and 12 μmol/L.

<10 µmol/L : favorable

No need to treat (target level of intervention)
10-12 µmol/L : tolerable

Need to treat symptomatic patients
12-13 µmol/L : moderate increase
>30 µmol/L : severe increase

Intervention required for all (apparently healthy individuals and patients)

Management of Hyperhomocysteinemia2

  • The HCY assay in combination with the clinical picture and underlying disease helps in determining the decision for treatment.
  • In mild-to-moderate hyperhomocysteinemia, HCY levels can be reduced by folate and vitamin B6 and B12 supplementation.

Reliable Answers to Critical Cardiac Questions

As a recognized leader in CVD testing, Siemens Healthcare Diagnostics offers multiple instrument choices for homocysteine testing, which allows for earlier identification of high-risk populations for cardiovascular diseases, facilitating initiation of quicker preventive and therapeutic measures.


Learn more


Homocysteine assays are available on the following systems from Siemens Healthcare Diagnostics:

Dedicated Immunoassay Systems

ADVIA Centaur® System
ADVIA Centaur® XP Immunoassay System
ADVIA Centaur® CP Immunoassay System
IMMULITE® 1000 Immunoassay System
IMMULITE® 2000 / IMMULITE® 2000 XPi Immunoassay System

Integrated Systems

Dimension® Vista Systems


Specialty Immunoassay Systems

BN ProSpec® System
BN ™ II System






1. Wald DS, et al. Br Med J. 2002;325:1202-8.
2. Macy PA. Clin Lab Sci. 2001;14:272-5.
3. Stanger O, et al. Clin Chem Lab Med. 2003;41:1392-403.
4. Stanger O, et al. Z Kardiol. 2004;93(6):439-53.
5. Maron BA, et al. Annu Rev Med. 2008. [Epub ahead of print].
6. American Heart Association. What is Homocysteine?
http://www.americanheart.org/presenter.jhtml?identifier=535. Dec. 2008.
7. van Meurs JB, et al. N Engl J Med. 2004;350:2033-41.
8. American Heart Association. Homocysteine, Folic Acid and Cardiovascular Disease.
http://www.americanheart.org/presenter.jhtml?identifier=4677. Dec. 2008.

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