Hematology and Oncology
Core concepts
Understand anaemia classification by MCV and reticulocyte response, iron studies (ferritin, transferrin saturation), and the workup of microcytic anaemia (iron deficiency, thalassaemia, anaemia of chronic disease, sideroblastic). Know the approach to thrombocytopenia (production vs consumption vs sequestration), coagulopathy (PT/APTT mixing studies), and the emergencies: febrile neutropenia, tumour lysis syndrome, hyperviscosity, and cord compression. Be familiar with lymphoma and leukaemia presentations, and the principles of oncological emergencies and staging.
Traps
Questions test ferritin as an acute-phase reactant - a normal ferritin does not exclude iron deficiency in inflammation. Distinguish DIC (prolonged PT/APTT, low fibrinogen, high D-dimer, schistocytes) from TTP (normal PT/APTT, low platelets, haemolysis, neurological/renal features). Do not give platelets in TTP unless life-threatening bleeding. In febrile neutropenia, antibiotics must be given within one hour - do not wait for cultures.
Rule of thumb
For any neutropenic patient with fever, start broad-spectrum antipseudomonal antibiotics immediately after cultures; escalate if unstable. For suspected cord compression, give dexamethasone and arrange urgent MRI.
Worked example
A patient with microcytic anaemia and a ferritin of 45 in the setting of inflammation: calculate transferrin saturation; if low, treat as iron deficiency and investigate the source, especially GI blood loss.