Homocysteine is an amino acid produced by the body.
Elevated homocysteine levels are linked to high concentrations of endothelial asymmetric dimethylarginine (ADMA); a chemical found in blood plasma. ADMA interferes with the synthesization of Nitric Oxide from L-Arginine. Nitric Oxide is important in our bodies because it increases blood flow. (Click here to read more on the role of Arginine and Nitric Oxide in our bodies)
It is important for Osteonecrosis (Avascular Necrosis) sufferers to have their homocysteine levels checked because high homocysteine levels cause narrowing of the arteries and can lead to excessive blood clotting.
Vitamins B6, B12 and Folic acid are commonly taken to lower homocysteine levels.
To read more about homocysteine go to: http://www.medicinenet.com/homocysteine/article.htm