Homocysteine is a chemical produced when an amino acid called methionine is broken down. Elevated homocysteine levels are linked to an increased risk of stroke, heart disease and peripheral artery disease. The risk of developing blood clots deep in the veins -- a condition known as deep vein thrombosis, or DVT -- is also increased with elevated homocysteine levels. These clots can travel to your lungs and cause a pulmonary embolism, or PE.
Causes of Elevated Homocysteine
Elevated homocysteine levels are mainly caused by vitamin B deficiencies -- especially B-6 and B-12 -- folic acid, renal impairment, certain drugs and genetics. Treatment focuses on supplementing with vitamins. When left untreated, elevated homocysteine levels can lead to atherosclerosis, or hardening of the arteries, and increased clot formation.
Homocysteine and Clots
In vitro studies show that homocysteine damages the cell lining and impairs the release of nitric oxide, which is a strong vasodilator. Vasodilation occurs when blood vessels relax and allow blood to flow freely. Narrow blood vessels restrict blood flow, making it easier for clots to reduce or even stop blood flow. Nitric oxide is also needed to prevent platelets in the blood from sticking together and forming clots, according to the Cardiovascular Research Journal. When homocysteine levels are too high, nitric oxide cannot be released, which results in the blood becoming stickier and makes it easier for clots to form.
Normal Lab Values
A normal homocysteine level is five to 15 micromoles per liter (mmol/L). Levels from 16 to 30 mmol/L are moderately high, and levels from 31 to 100 mmol/L are intermediately high. A level greater than 100 mmol/L is very high. Ten to 20 percent of people who have a DVT have elevated homocysteine levels, and the risk of DVT increases as homocysteine levels increase. One group of studies found that every 50 percent increase in homocysteine raised the risk of PE or DVT by 60 percent.
Treatment
Homocysteine levels may drop if you eat a diet rich in folic acid and B vitamins. Green, leafy vegetables and fortified grain products are rich in these nutrients. Supplements are available for folic acid and the B vitamins, but you should consult your health care provider before taking any supplements. Research has not yet shown that lowering your homocysteine levels reduces your risk of death, according to the Mayo Clinic.
