Hematology
Hematology tests anaemia classification, iron studies, haemolysis, haematological malignancy and transfusion-related complications.
Anaemia
- Microcytic: iron deficiency, thalassaemia, anaemia of chronic disease, sideroblastic anaemia.
- Iron deficiency: low ferritin, low serum iron, high total iron-binding capacity, low transferrin saturation.
- Thalassaemia trait: normal or high ferritin, target cells, Mentzer index (MCV/RBC) below 13.
Haemolysis
Raised lactate dehydrogenase and indirect bilirubin, low haptoglobin, reticulocytosis; a positive direct antiglobulin test indicates autoimmune haemolysis.
Malignancy
- CML: t(9;22) BCR-ABL, treated with imatinib.
- Acute promyelocytic leukaemia: t(15;17), treated with ATRA; high risk of disseminated intravascular coagulation.
- Hodgkin lymphoma: Reed-Sternberg cells, CD15 and CD30 positive.
Coagulation
- Heparin-induced thrombocytopenia: platelet fall at 5–10 days with thrombosis, not bleeding. Stop heparin and use argatroban.
- DIC: prolonged PT and aPTT, low fibrinogen, high D-dimer, schistocytes.
Worked example
A patient on unfractionated heparin for 6 days has platelets falling from 250 to 90 ×10⁹/L and a new leg swelling. This is heparin-induced thrombocytopenia with thrombosis. Stop all heparin, start a non-heparin anticoagulant, and do not give platelets.
Traps
Giving platelets in HIT, treating iron deficiency without finding the source, and missing DIC in APL.