Homocysteine is a sulphur bearing amino acid produced as the body digests protein. The test for homocysteine is also known as the plasma total homocysteine, and it is a screening test for people at risk for heart attack, stroke, and peripheral vascular disease: Studies have shown that high levels of homocysteine in the blood (hyperhomocysteinemia) are linked to greater risk for these diseases.
Homocysteine causes cholesterol to change into oxidized low-density lipoprotein (LDL), the bad cholesterol, which damages the arteries. High homocysteine levels may also cause blood to clot more easily than normal, which would increase the risk of blockages (stroke). Homocysteine has also been linked to other diseases, including Alzheimer's disease, problem pregnancies, and some cancers. Pregnant women with high levels of homocysteine have an increased risk of having children with neural tube defects and other congenital defects.
Whether or not to test for homocysteine is a question of much controversy. Here are some points to consider as you determine whether you should be tested for homocysteine:
- The American Heart Association has not established a direct relationship between homocysteine levels and heart attacks. The AHA does suggest that for those people with a family history of cardiovascular disease but none of the risk factors themselves (i.e. high blood pressure, obesity, diabetes, smoking, high blood cholesterol or lack of exercise), screening may be useful.
- Tests for homocysteine levels are often ordered as part of a cardiac risk assessment or following a heart attack or stroke. Tests are also ordered if a doctor suspects a B-vitamin/folate deficiency or when a baby shows symptoms of homocystinuria, a hereditary metabolic error caused by a defective enzyme (cystathionine synthetase) needed to digest the amino acid, methionine. (These tests are part of newborn screenings in some states.)
- High homocysteine levels increase the risk of complications from Type 2 diabetes significantly.
- High homocysteine levels have been linked to an increased likelihood of osteoporosis in the elderly.
- If you do test positive for high levels of homocysteine, tests for urine and blood concentrations may be taken 2-3 times per year to help determine the course of treatment.
- A diet high in vitamins B-6, B-12 and folic acid decreases homocysteine levels. Some foods that contain high levels of folic acid are green leafy vegetables and grain products fortified with folic acid. You can find a detailed list of foods with high folate content here.
- Vitamin B-6, B-12 and folic acid are also available in supplement form. Because the elderly tend to be deficient in vitamin B-12 (the ability to absorb the vitamin from the small intestine declines with age), they would benefit from supplements.
- Thyroid hormone, kidney disease, psoriasis, and some medicines can cause high homocysteine levels.