[Present role of homocysteine in clinical medicine].

There has been a great interest in the last decades about the clinical significance of elevated total plasma homocysteine (tHcy), and especially its possible association with an increased cardiovascular risk. Measurement of tHcy is clearly indicated when homocystinuria is suspected in young or adult patients (in the presence of a severe, atypical or progressive myopia with ectopia lentis and/or venous thromboembolism and/or severe, premature or atypical atherosclerotic vascular disease) and in the evaluation of vitamin B12 and/or folic acid deficiencies. The current evidence does not support either the screening measurement of tHcy or the treatment with vitamin B12 and/or folic acid supplementation in patients with cardiovascular disease. It is important to remember that it remains to be proved whether the long-term administration of folic acid at pharmacological doses is safe.