The role of cysteine and homocysteine in venous and arterial thrombotic disease

Hyperhomocysteinemia is a risk factor for arterial and venous thrombosis, w hereas few data are available on the total cysteine (tCy) levels in thrombo philic patients. We studied 82 patients with a previous myocardial infarcti on (MI; group 1), 68 patients with a previous deep venous thrombosis (group 2), and 100 control subjects (group 3). We assayed total homocysteine (tHc y) and tCy levels by high-performance liquid chromatography with fluorimetr ic detection. The odds ratios (ORs)for high levels of tCy and tHcy in venou s thrombosis and MI were markedly increased in group 1 (fasting tCy: OR, 3. 6; 95% confidence interval[CI] 1.6-11.2; postmethionine tCy: OR, 0.97; CI, 0.3-4.0;fasting tHcy: OR, 8.3; CI, 3.9-18.6; postmethionine tHcy,: OR, 12.5 ; CI, 6.8-27.2) and in group 2 (fasting tCy: OR, 2.9; CI, 1.1-7.8; postmeth ionine tCy: OR, 0.86; CI 0.2-2.6; fasting tHcy: OR, 8.0; CI 3.6-18.0; postm ethionine tHcy: OR, 11.0 CI, 6.0-22.1). Our data suggest that plasma tCy le vels nr e a risk factor for venous thrombosis and MI independently of tHcy levels and that it may be appropriate to study both variables simultaneousl y to thoroughly study the methionine metabolism.