Serum Homocysteine can be a diagnostic test for multiple pathological conditions.

Elevated blood levels of the amino acid homocysteine have been implicated as a strong predictor for heart disease, independent of the person’s cholesterol or lipid profile. Homocysteine is formed as an intermediate product during metabolism of the essential dietary amino acid methionine. Homocysteine contributes to atherosclerosis by promoting proliferation of vascular smooth muscle cells, an early step in development of the artery-clogging condition. Furthermore, homocysteine appears to damage endothelial cells and may cause oxidation of LDL, both of which contributes to plaque formation. Three B vitamins- folic acid, vitamin B12 and vitamin B6- all play key roles in pathways that clear homocysteine from the blood. Therefore, these B vitamines are all needed to keep blood homocysteine at safe levels.

Serum homocysteine concentration were associated with high frequency of thrombosis, an elevated plasma homocysteine level was positively associated with elevated plasma Tn I level (troponin I ). This is related to myocardial injury.