Homocysteinemia and endothelial damage after methionine load.

Homocysteinemia increased significantly after a methionine load of 50 mg/kg in patients with peripheral artery occlusive disease but this load was insufficient to increase circulating endothelial cell count as a marker of endothelial damage. Only after an increased load of 100 mg/kg methionine circulating endothelial cells also increased markedly confirming the results of a previous experimental study. These data indicate a threshold concentration of homocysteine in blood necessary to induce endothelial lesions.