Hyperhomocyst(e)inemia and Thrombophilia.

Objective: To review the role of an elevated total plasma homocysteine level (hyperhomocyst[e]inemia) in patients with venous or arterial thrombosis, as reflected by the medical literature and the consensus opinion of recognized experts in the field.

Data Sources: Review of the medical literature, primarily from the last 10 years.

Data Extraction And Synthesis: The literature was reviewed to identify key points defining the condition, and the clinical study design of each article was examined. A draft manuscript was prepared and circulated prior to the conference to every participant in the College of American Pathologists Conference XXXVI: Diagnostic Issues in Thrombophilia. Each of the key points and associated recommendations was then presented for discussion at the conference. Recommendations were accepted if a consensus of the 70% of the experts attending the conference was reached. The results of the discussion were used to revise the manuscript into its final form.

Conclusions: Consensus was reached on 9 recommendations concerning the criteria for diagnosis, the method of testing, and the approach for clinical management. A major point of consensus was that no causal role of hyperhomocyst(e)inemia in venous or arterial thrombosis is yet established. Testing methods used to measure homocysteine directly are sensitive and reliable, and provide more information than does genotyping for markers linked to abnormal plasma homocysteine.