Hematology and Oncology
Core concepts
Understand the anemias by MCV: microcytic (iron deficiency, thalassemia, anemia of chronic disease), normocytic (hemolysis, CKD, acute blood loss), macrocytic (B12/folate, alcohol, hypothyroidism, MDS). Know the iron studies pattern (low ferritin, low iron, high TIBC in iron deficiency; high ferritin, low TIBC in anemia of chronic disease). Cover the leukemias and lymphomas at a conceptual level, the approach to a bleeding patient (platelet count, PT/INR, aPTT, mixing studies), heparin-induced thrombocytopenia, and the oncologic emergencies: febrile neutropenia, tumor lysis syndrome, superior vena cava syndrome, spinal cord compression, and hypercalcemia.
Traps
Ferritin is an acute-phase reactant and can be falsely normal in iron deficiency with inflammation - check transferrin saturation. Exam questions test the difference between DIC (prolonged PT and aPTT, low platelets, high D-dimer, schistocytes) and TTP (normal PT/aPTT, low platelets, hemolytic anemia, neurologic/renal involvement) - TTP needs urgent plasma exchange. In febrile neutropenia, give broad-spectrum antibiotics within one hour without waiting for cultures.
Worked rule of thumb
Microcytic anemia with high red cell distribution width and low ferritin = iron deficiency. If ferritin is normal but suspicion is high, check transferrin saturation; <20% supports iron deficiency even when ferritin is confounded.
Key points
- MCV-based classification drives the anemia workup.
- Ferritin can be falsely normal in inflammation.
- TTP: normal coagulation, urgent plasma exchange.
- DIC: prolonged PT/aPTT with low platelets and high D-dimer.
- Febrile neutropenia: antibiotics within one hour.