What is being tested?This test determines the level of homocysteine in the blood or urine. Homocysteine is a sulfur-containing
amino acid that is normally present in very small amounts in all cells of the body. Homocysteine is a product of methionine metabolism. Methionine is one of the eleven “essential” amino acids - amino acids that must be derived from the diet since the body cannot produce them. In healthy cells, homocysteine is quickly converted to other products.
Vitamins B6, B12, and folate are necessary to metabolize homocysteine. Patients who are deficient in these vitamins may have increased levels of homocysteine.
Recent studies have suggested that people who have elevated homocysteine levels have a much greater risk of heart attack or stroke than those with average levels. Increased concentrations of homocysteine have been associated with an increased tendency to form inappropriate blood clots. When this happens it can lead to heart attack, strokes, and blood vessel blockages in any part of the body.
Homocysteine can be greatly increased in the blood and urine of patients with a rare inherited condition called homocystinuria. This disorder is caused by an alteration in one of several different genes. The affected person has a dysfunctional enzyme that does not allow the normal breakdown of methionine. Because of this, homocysteine and methionine begin to build up in the person’s body. A baby with this condition will appear normal at birth but within a few years will begin to develop signs such as a dislocated lens in the eye, a long slender build, long thin fingers, skeletal abnormalities, osteoporosis, and a greatly increased risk of thromboembolism and of atherosclerosis that can lead to premature cardiovascular disease. The buildup may also cause progressive mental retardation, behavioral disorders, and seizures.
