Homocysteine is a compound found inthe blood that is produced by the breakdownof methionine. Elevated levels ofhomocysteine have been shown to be arisk factor for development of atherosclerosisand venous thrombosis. High homocysteinelevels may be caused by a deficiencyof folic acid or B vitamins in thediet, kidney disease, hypothyroidism,psoriasis, systemic lupus erythematosus,or medications such as methotrexate orphenytoin. Genetic variants may alsocause hyperhomocystinemia.
Studies have shown that elevatedhomocysteine levels nearly double therisk of venous thrombosis; however, loweringthe level does not appear to lowerthe risk of these events. The mechanismof this increased risk is not well understood.Homocysteine levels can be loweredby increasing the amount of folateand B vitamins in the diet or supplementationwith commercially available combinationsof vitamin B6, B12, and folate.
No specific guidelines exist regardingtesting. Measurement of serum homocysteinelevels may be prudent in patientswith unexplained blood clots or atherosclerosis.Although preliminary studieshave not shown that lowering levels lowersrisk, supplementation may be advisableuntil this issue has been further defined.
Dr. Garrett is a clinical pharmacistpractitioner at Cornerstone HealthCare in High Point, NC.