ASHG ACMG STATEMENT - MEASUREMENT AND USE OF TOTAL PLASMA HOMOCYSTEINE/

Hyperhomocysteinemia, which is a recognized independent risk factor fo r premature vascular occlusion, is defined as a fasting total plasma h omocysteine (tHcy) level >15 mu M. There may also be graded increased risks for persons with tHcy concentrations of 10-15 mu M. The measurem ent of tHcy requires precise sample collection, immediate separation a nd freezing of plasma, and referral to a specialized laboratory. The e tiologies of hyperhomocysteinemia are complex and involve both genetic and environmental factors. Because the inappropriate supplementation of involved cofactors can be harmful, it is important to identify the cause of hyperhomocysteinemia prior to treatment.