Homocysteine With UTSH

Homocysteine is an amino acid that is typically present in very small amounts in all cells of the body. That is because the body normally converts homocysteine into other products quickly. Since vitamins B6, B12, and folate are necessary to metabolize homocysteine, increased levels of the amino acid may be a sign of deficiency in those vitamins. This test determines the level of homocysteine in the blood and/or urine.

Elevated homocysteine may also be related to a higher risk for coronary heart disease, stroke, peripheral vascular disease (fatty deposits in peripheral arteries), and hardening of the arteries (atherosclerosis). High levels of homocysteine increase the risk of blood clot formation in vessels and may lead to heart attack and stroke. Several mechanisms have been proposed for how homocysteine leads to cardiovascular disease (CVD) risk, but direct links haven not been confirmed. There are also several studies that indicate no benefit or lowering of CVD risk with folic acid and B vitamin supplements. So far, the American Heart Association does not consider it a major risk factor for heart disease.

A rare inherited condition called homocystinuria can also greatly increase homocysteine in the blood and urine. 

How is it used?

The homocysteine test may be used the following ways:

• A healthcare practitioner may order a homocysteine test to determine if a person has a vitamin B12 or folate deficiency. The homocysteine concentration may be elevated before B12 and folate tests are abnormal. Some healthcare practitioners may recommend homocysteine testing in malnourished individuals, the elderly, who often absorb less vitamin B12 from their diet, and individuals with poor nutrition, such as drug or alcohol addicts.
• Homocysteine may be ordered as part of a screen for people at high risk for heart attack or stroke. It may be useful in someone who has a family history of coronary artery disease but no other known risk factors, such as smoking, high blood pressure, or obesity. However, the exact role that homocysteine plays in the progression of cardiovascular disease has not been established, so the utility of the screening test continues to be questioned. Routine screening, such as that done for total cholesterol, has not been recommended.

When is it ordered?

This test may be ordered when a health practitioner suspects that a person may have a vitamin B12 and/or folate deficiency. Signs and symptoms are initially subtle and nonspecific. People with an early deficiency may be diagnosed before they experience any overt symptoms. Other affected people may experience a variety of mild to severe symptoms that can include:

• Diarrhea
• Dizziness
• Fatigue, weakness
• Loss of appetite
• Paleness
• Rapid heart rate
• Shortness of breath
• Sore tongue and mouth
• Tingling, numbness, and/or burning in the feet, hands, arms, and legs (with B12 deficiency)

Homocysteine testing may be ordered as part of assessing a person’s risk of cardiovascular disease, depending on the individual’s age and other risk factors. It may also be ordered following a heart attack or stroke to help guide treatment.