Internal Medicine Exam Study Guide 2026

Warfarin inhibits vitamin K-dependent factors (II, VII, IX, X), which are measured by the PT/INR; the aPTT monitors heparin therapy.

This pattern indicates immunity from a past, resolved natural infection. The presence of Anti-HBs confers immunity. The presence of total Anti-HBc indicates previous exposure to the core antigen, which only occurs during natural infection, not vaccination. Immunity from vaccination would show a positive Anti-HBs but a negative Anti-HBc. Acute infection would have a positive HBsAg and positive IgM Anti-HBc. Chronic infection would have a positive HBsAg.

Classic HIT (type II) develops 5-10 days after starting heparin due to the time required for antibody formation against platelet factor 4-heparin complexes.

Von Willebrand disease impairs platelet adhesion and primary hemostasis, leading to mucocutaneous bleeding; hemarthroses are more typical of hemophilia.

APS is a thrombophilic condition caused by antiphospholipid antibodies that promote clotting, leading to arterial/venous thrombosis and recurrent pregnancy loss.

A low serum ferritin is highly specific for iron deficiency anemia; in anemia of chronic disease, ferritin is normal or elevated because it is an acute-phase reactant.