Hematology and oncology — anemia, coagulation, leukemias
**Anemia by MCV:** • **Microcytic (<80):** iron deficiency (low ferritin), thalassemia (normal ferritin, HbA2 ↑ in β-thal), anemia of chronic disease (low TIBC, normal/↑ ferritin), sideroblastic, lead. • **Normocytic:** hemolysis (retic ↑, LDH ↑, haptoglobin ↓, indirect bili ↑), aplastic, CKD (EPO deficient). • **Macrocytic (>100):** megaloblastic — B12, folate (B12 deficiency also causes neuro — treat B12 first); non-megaloblastic — liver, hypothyroid, alcohol.
**Hemolysis:** • Intrinsic — hereditary spherocytosis (osmotic fragility), G6PD, sickle cell, PNH (flow CD55/CD59 loss), enzyme deficiencies. • Extrinsic — autoimmune (Coombs), MAHA (TTP, HUS, DIC), mechanical (prosthetic valve).
**Coagulation:** • PT/INR — extrinsic (factor VII). PTT — intrinsic (VIII, IX, XI, XII, vWF). • Hemophilia A (VIII, X-linked), B (IX). vWD (most common inherited bleeding disorder): bleeding + prolonged PTT (vWF carries VIII). • DIC — consumption, ↑PT/PTT, ↓fibrinogen, ↑D-dimer. • TTP (ADAMTS13 <10%) — pentad: MAHA, thrombocytopenia, fever, renal, neuro. Plasma exchange.
**Leukemias (age/features):** • ALL — kids, t(12;21) good prog; adult Ph+ with TKI. • AML — adults, Auer rods, APL t(15;17) = ATRA + arsenic. • CLL — older adults, smudge cells, Richter's transformation. • CML — t(9;22) BCR-ABL; imatinib.
**Lymphomas:** Hodgkin — Reed-Sternberg 'owl eyes'; bimodal. NHL — diffuse large B-cell (most common aggressive), follicular (most common indolent), Burkitt (c-myc t(8;14) 'starry sky').
**Multiple myeloma:** CRAB — hyperCalcemia, Renal, Anemia, Bone. M-spike, Bence Jones proteinuria.