Homocysteine Test

The homocysteine test is a blood test that measures the level of homocysteine in your blood. The test is one way to determine the risk of heart disease. It can be used as a blood test for heart attack.

Cardio-Med offers the hs CRP test in addition to the homocysteine test for in-depth assessment of risk of heart disease.

What is homocysteine?

Homocysteine is an amino acid. Amino acids are the building blocks of proteins. When proteins break down, elevated levels of amino acids like homocysteine may be found in the bloodstream. Elevated levels of homocysteine in the blood may indicate atherosclerosis (narrowing of blood vessels) or blood clots.

It is not possible to get homocysteine from the diet. It must be made from methionine, an amino acid found in meat, fish, and dairy products. Vitamins B6 (pyridoxine), B12 and folic acid are needed for its production.

Foods containing methionine are transformed into homocysteine in the bloodstream. Homocysteine is converted in the body to cysteine, with vitamin B6 facilitating this reaction. Homocysteine can also be recycled back into methionine using vitamin B12-related enzymes.

Cysteine has many roles in the body. It is involved in the way proteins within cells are folded, maintain their shape, and link to each other. Cysteine is a source of sulfide and is part of the metabolism of metals in the body such as iron, zinc and copper. Cysteine also acts as an anti-oxidant.

If homocysteine cannot be converted into cysteine or returned to the methionine form, it accumulates. Elevated homocysteine levels have been associated with heart attack, stroke, blood clot formation, and perhaps the development of Alzheimer's disease.

Why are homocysteine levels measured?

Elevated levels of homocysteine are associated with heart attack, stroke and blood clots. If a person develops any of these diseases and does not have increased risk factors such as smoking, high blood pressure, high cholesterol, or diabetes, elevated homocysteine may be a factor.

What are the possible symptoms and signs of elevated homocysteine levels?

Elevated homocysteine levels in the body do not cause any symptoms but can have adverse effects on health nonetheless.
  • Elevated homocysteine levels affect the interior lining of blood vessels in the body, increasing the risk of atherosclerosis (narrowing of blood vessels). This can result in early heart attack and stroke.
  • There is a relationship between the levels of homocysteine in the body and the size of the carotid arteries that supply the brain with blood; the higher the homocysteine level, the narrower the carotid artery.
  • The risk of deep vein thrombosis and pulmonary embolism may also be linked to elevated homocysteine levels in the body.
  • There may be a relationship between elevated homocysteine levels and broken bones, especially in the elderly.
  • Alzheimer's disease and other types of dementia may occur frequently in patients with increased homocysteine in the blood.
  • In pregnancy, homocysteine levels tend to decrease. Elevated homocysteine levels may be associated with some fetal abnormalities and with potential blood vessel problems in the placenta, causing abruption. There may also be an association with pre-eclampsia.

What are high homocysteine levels?

Any measurement above 15 micormoles per liter is considered high. Optimal homocysteine levels are below 10 to 12.

The level of homocysteine is classified as moderate, intermediate or severe as follows:

  • Moderate (15 to 30 micromoles/liter)
  • Intermediate (30 to 100)
  • Severe (greater than 100)

What causes elevated homocysteine levels?

Homocysteine levels increase in the body when the metabolism to convert cysteine to methionine is impaired. This may be due to dietary deficiencies in vitamin B6, vitamin B12, and folic acid.

While alcoholics tend to be malnourished and lacking in B vitamins, alcohol itself may independently cause homocysteine levels in the blood to rise.

Can elevated homocysteine levels be hereditary?

Genetic abnormalities may affect the body's ability to metabolize homocysteine into cytsteine, causing elevation of homocysteine levels in the blood and urine. Screening is often suggested in infants if there is a family history of this disease.

How can homocysteine levels be lowered?

The treatment for homocysteinuria is vitamin supplementation with pyridoxine (vitamin B6), vitamin B12, and folic acid. The effects of vitamin treatment may be monitored by routine scheduled blood tests.

Some patients do not respond to the vitamin supplements and are considered pyridoxine-resistant. A diet low in methionine is recommended in addition to the B vitamins.

Who should have his homocysteine levels tested?

Homocysteine levels are often measured when a patient suffers a heart attack or stroke and has no risk factors for that illness (smoking, high blood pressure, high cholesterol, diabetes).

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Adapted from eMedicineHealth