Determination and utilisation of the plasmatic concentration of homocysteine in clinical practice

Homocysteine is a methionine-derived amino acid and its metabolism depends on B12, B6 and B2 vitamins and folic acid. The total homocysteine plasmatic concentration can be measured in most laboratories by means of enzymeimmunoassays. Hyperhomocysteinemia may be caused by genetic defects of the enzymes involved in its metabolism, nutritional deficiencies or absorption deficiencies of the vitamin cofactors of these enzymes, chronic diseases or administration of some drugs. An increase in the total plasmatic concentration of homocysteine represents a sensitive marker of folate and cobalamine deficiencies as well as an independent risk factor of cardiovascular disease. Furthermore, total plasmatic concentrations of homocysteine are related to the development of congenite malformations, pregnancy complications, psychiatric diseases and to cognitive impairment in the elderly. Therefore, the measurement of the concentration of homocysteine has a notable clinical interest, which may increase in future if it is confirmed that the association with these disorders is causal and that they can be prevented by treating hyperhomocysteinemia.