Diagnostic evaluation of hypercoagulable states

(not routinely required for initial VTE; NEJM 2017;377:1177)

• APC resistance screen; prothrombin PCR test; functional assays for proteins C and S, ATIII; homocysteine level; factor VIII levels; anticardiolipin and lupus anticoagulant Ab. Also consider nephrotic syndrome, PNH (esp. if mesenteric thrombus).

• Consider JAK2 mutation testing if suspect MPN or splanchnic thrombosis

• Proteins C & S and ATIII levels unreliable during acute thrombosis and anticoagulation ∴ levels best assessed ≥2 wk after completing anticoagulation course

• Age-appropriate malignancy screening (occult cancer in ~4% of initial unprovoked VTE; no benefit of routine abd/pelvis CT; NEJM 2015;373:697)