Haematology and Transfusion Medicine: Anaemia, Coagulation and Malignancy
Core concepts
Haematology covers anaemia classification, iron studies, haematinics, haemolysis, haemoglobinopathies, coagulopathy, thrombocytopenia, transfusion medicine and haematological malignancy. Use MCV to classify anaemia as microcytic, normocytic or macrocytic. Iron deficiency shows low ferritin, low transferrin saturation and raised total iron-binding capacity; anaemia of chronic disease shows normal or high ferritin with low saturation. Haemolysis features raised reticulocytes, unconjugated bilirubin and LDH with low haptoglobin. Know DIC, TTP, heparin-induced thrombocytopenia, neutropenic sepsis and transfusion reactions.
Traps
Ferritin is an acute-phase reactant and can be normal in iron deficiency with inflammation. Combined iron and B12 deficiency can produce a normal MCV. Do not give platelets routinely in TTP; urgent plasma exchange is the treatment. A falling platelet count after heparin suggests HIT. In neutropenic sepsis, do not wait for cultures before giving broad-spectrum antibiotics. Transfusion reactions require stopping the transfusion and maintaining venous access.
Worked example / rule of thumb
A woman with heavy periods has Hb 8.5 g/dL, MCV 72 fL, ferritin 8 micrograms/L and transferrin saturation 10%. This is iron deficiency anaemia; investigate the cause and give oral iron. Rule: a low ferritin in the right clinical setting confirms iron deficiency, but a normal ferritin does not exclude it when inflammation is present.