F5 and hyperinsulinemic hypoglycemia, familial, 4: In this case and similar cases, a hypercoagulable workup should include testing for Factor V Leiden and prothrombin 20210 mutations, deficiency of protein C, protein S, and antithrombin III; elevation of clotting factors VIII, IX, XI, and fibrinogen and homocysteine levels; and testing anticardiolipin antibodies.