Internal Medicine

0521779407-20 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:22

1422 Thrombophilia

■High levels of FVIII, FIX, FXI (above the 90th percentile)

■Caval filter

■Post-thrombotic syndrome

Acquired Conditions Predisposing to Both Venous and Arterial Throm-

bosis

■Hyperhomocysteinemia

■Paroxysmal nocturnal hemoglobinuria

■Antiphospholipid antibodies (anticardiolipin antibodies, lupus anti-

coagulant)

■Myeloproliferative diseases

■Heparin-induced thrombocytopenia

■Tobacco use

■Vasculitis

Acquired Conditions Predisposing only to Arterial Thrombosis

■Hyperlipidemia

Factor V Leiden

■Caused by a point mutation in the factor V gene, leading to change

at the major Protein C cleavage site (FV R506Q)

■Frequency varies from 1% to 8%. Found mainly in Caucasians.

■Found in 20–50% of patients with venous thrombosis

■Relative risk for thrombosis is 5-fold in heterozygous patients.

■Relative risk for thrombosis is 50-fold in homozygotes.

■Oral contraceptives increase risk in heterozygous patients by

48-fold.

Prothrombin Mutation

■Caused by a point mutation in the 3′untranslated region of the pro-

thrombin gene (G20210A)

■Leads to increased levels of prothrombin

■Frequency varies from 0.7–4.0%.

■Found in 6–20% of patients with venous thrombosis

■Relative risk for thrombosis is 2.5.

Protein C Deficiency

■Frequency estimated to be 0.2%

■Found in 3% of patients with venous thrombosis

■Homozygotes develop neonatal purpura fulminans, cerebral vein

thrombosis.

■Heterozygotes have 10-fold increased relative risk for venous throm-

bosis and increased risk of developing warfarin skin necrosis.